+++ #218 Subject: Tyvek coveralls for spraying From: Russ Erb At last I found a source for them... When I first bought some coveralls at the local hardware store for spraying parts in my paint booth, the package showed a collar, open wrists and ankles. To my surprise, what I pulled out had a hood, elastic wrists, and feet--which turned out to be just what I needed. Unfortunately, it turned out to be an isolated mistake. As I looked around the local hardware stores and home centers for hooded, footed coveralls, I couldn't find any. The hoodless, footless style are fine for rolling latex paint, but not real useful in a spray booth. I mentioned my lack of success to a friend who suggested checking with McMaster-Carr. I came home and fired up their web site (http://www.mcmaster.com). After a little searching, I found exactly what I was looking for. It is catalog number 5231T39. The "deluxe" style has the hood and feet. They're on page 1360 of the catalog. I ordered them through the web site for $5.92 a piece. +++ #2587 William & Delinda Johnson Subject: 023 Update 2. Painting - All parts are cleaned with PPG DX330 wax and grease remover, etched with PPG DX 533 aluminum cleaner (I use aluminum cleaner even on the 4130), and cleaned again with PPGDX330. Aluminum parts are conditioned with DX503 and zinc cromated. 4130 parts are sprayed with PPG epoxy primer (see picture above). +++ #2697 From: Bill Shellenberger Subject: Hipec I've been looking into using Hipec paint, but I can't find any builders who have used it. I wonder if any of you Bearhawk builders from Canada have any knowledge about this product or anyone who has used it that I can talk to. Thanks for your help. +++ #2715 From: Rob Gaddy Subject: models Would anyone be interested in an inexpensive cast non-flying model of the bearhawk? I was thinking something to try out a paint scheme, in 3 dimensions, something to hang in the shop for inspriation. +++ RAH From: tailwind@iinetsplotnetsplotau.rubbish.con (Stealth Pilot) Subject: Re: tube fuse cleanup >> What's the preferred way to clean up a steel tube fuse that's been >> exposed for a little while? A tip here for tube fuselages. I used a small airbrush to do the job. a chinese copy of a revell modellers airbrush. the entire fuselage was painted in under a quart, 3 coats and almost no overspray. the little airbrush isnt slow either. stealth pilot +++ #3441 Subject: 3D view & Jery Stains From: Tim Cramb > "As much as I admire Bob Barrows, I'm leaning toward putting a 3D > view drawing of the Bearhawk on my office wall, and I'm hoping > Mike has a better copy of this on file than I do. I'd reduce my > own drawing, but it's been so manhandled I don't think it would > work out. It's got coffee and jerky stains all over it. Man... > jerky stains sounds like something really bad. That's disgusting. > You folks are a VERY sick bunch, indeed!" 3d view file would be a good idea, especially for paint schemes. Any good print shop should be able to produce some experimentation copies from download onto 3.5" disc. Oh yeah, Bob if you keep pulling back on that 'Stick' so hard you may exceed 'G' limits and flip her over onto her back..............No Silly, I'm talking about your office chair ;-) +++ #4178 From: "Gary Danford" Subject: paint booth hear I enjoyed the discussion about heating workshops and have a question for the group. I have a 10X10 ft area in my shop (out of plastic sheeting) equiped with an exaust fan. It works perfect for painting and fabric covering but in the winter its too cold to paint. Poly-fibre recommends a minimum of 60 degrees F to use their products. So with that said I wanted to use a "Infrared Spot Heated" (110V) and very inexpensive to heat the paint booth. The plan is to heat the booth, turn the heater off, paint the parts, exhaust the over spray, turn the heater back on to dry the paint!!!! Questions: 1. The "Infrared Spot Heater" uses a quartz tube as the heating element so no sparks or direct flame and the fan exhausts "most" of the vapor etc. 2. Do you think there will be a loud boom? 3. Any other ideas for heating a paint booth. +++ #4181 From: Russ Erb Subject: [Bearhawk] paint booth hear I haven't seen the actual heater, but from your description I don't think it will work for what you want. Sounds like it emits infrared radiation, which only heat something when they touch it. Doesn't heat air worth krap. Ever stand by a campfire on a cold night when you get very hot on the side next to the fire and stay cold on the other side? For that matter, stand in the summer sun in a black shirt and get hot on the side toward the sun but not the other. The intent of these heaters is to put them next to you in the office pointed at you. They save energy by only heating you without heating all of the air around you. I have never cared for such heaters. I only buy convective heaters--the ones with a fan that blows over heating elements. My technique has been to heat the entire room where the paint booth is long enough to bring all of the items in the room up to temperature. The heaters are outside the paint booth. The warm air goes in and is exhausted outside. I only run the exhaust fan while actually spraying, since its purpose is to remove the overspray so it doesn't fog up. When done spraying, I turn the fan off. This is a benefit of Poly Fiber's water borne primer--no solvent vapors to have to keep exhausting (also it's tough to light water on fire, even with sparks or direct flame). The room doesn't cool down that fast, surprisingly. I think it may be because of the heat stored in all of the stuff in the room. When in Colorado, I had a paint booth in the basement, exhausted to the outside. The air came into the basement through the house, so it never really cooled down. Why does it occur to me that we would not be having this discussion in August...? +++ #4186 From: "DANFORD, GARY" Subject: RE: [Bearhawk] paint booth hear It appears to me if the heater heats up what you're painting and heats up the paint and keeps your parts up to temp while the paint dries, what else do you need. My worry is about combustive solvents released into the air while the paint drying. The problem I've always had with convective heaters is the dirt particles they stir up when they are running. I've always had problems with dirt particles getting into the paint even with filters,and in a paint booth. I've wetted the floor, wore a clean suit, used a filter mask and still dirt particles. It is really hard to keep dirt out of high gloss paint. The Poly-Tone water base primer apparently dries fast and is not high gloss but the multi-coats of poly brush, poly spray and Aerothane dry more slowly and release a lot of solvents thus my original question, "How can you heat a paint booth in extremely cold weather" +++ #4189 From: "Paul Foster" Subject: RE: [Bearhawk] paint booth hear Lots of ways to make this work but how about heating the floor. If on concrete build a false floor with 2x4 or 6 and sheet with plywood or chipboard. Use caulk to seal the cracks from the back. Design so the air can circulate in a zig zag path by having a short joist every other one. Fasten the booth plastic to the false floor. Hook up one or two convective electric heaters with duct work and let the warm air circulate. The floor can be covered with plastic for dust control or the floor damp mopped to control dust. The floor could be painted with floor paint to give an easier to clean surface. The same idea could be used but with hot water under a 2X2 floor. Could rig up another zone off of house hot water heating system and install the plastic pipe under the false floor. Building a new shop? Put the heat in the floor using the hot water. I have a low temperature forced air solar system on my shop, with a 7x38 vertical collector built into the wall. I circulate air through a cobblestone storage under the concrete floor. Low volume of air enters the floor at 80-100F and exits at about 40F. My floor is not warm to touch but the heat makes a difference. With no supplemental heat I consistently see a 20F and often a 30F difference between outside temp and inside temp in the morning. I have about 200 sq feet of insulation to install to finish which should improve the differential. Have a R25 throughout the building. We are fortunate to have about 300+ days of sunshine per year. +++ #4190 From: budd davisson Subject: Re: [Bearhawk] paint booth heat Somewhere back in the early BH e-group days, I related how I built my hangar/shop with a wooden floor on joists with the air piped under it exactly as you describe. It had several added advantages including I could figure out where I wanted the air for a particular project and cut a floor vent. Mostly though, the wood made a softer working surface that was easy on the legs/back and I could jig/nail/glue directly to it when setting stuff up. I made mine with a double layer of 5/8 OSB (like flake board) so I could peel the outter layer off, when it got too scarred up and it was stiff enough to drive a car onto. I did this after I broke down and built a plenum on the forementioned heater and used big, surplus scat hose to duct it into the floor. I had a plastic sheeting paint/sandblasting booth that dropped from the ceiling, but my explosive proof fan through the outside wall turned out to be about twice what I needed. It threatened to suck the tent overboard and would practically yank my then-four year old off the floor. +++ #4191 From: "Paul Foster" Subject: RE: [Bearhawk] paint booth hear After more contemplation I offer the following: Another way to get the heat in the booth would be to build a false top on top of work bench where you are laying the parts or hang parts above bench and circulate the heat through the bench top. This would work if a small booth. The heater could be rigged on a thermostat so would not over heat. The "milk house" heater can be rigged to reticulate the air so not heating cooler outside air. An easy way to make a small insulated booth would be to use ridged insulation and fasten with long nails and duct tape. Set on top of the heated floor. Hinge a 4x8 framed panel for a door, rig an exhaust fan (cover outlet when done spraying) and install a couple of flourescent shop lights and you are set. +++ #4193 From: Jim Ash Subject: Re: [Bearhawk] paint booth hear Caution: The infrared heater emits infrared radiation (light) that won't heat the air in the booth; it will heat what stops the light it emits. This works OK for food and bus stops, but I'm not sure how it will work for a freshly sprayed paint surface. I might be inclined to aim the heat lamps away from the work surfaces and let them warm up everything else inside your booth. I have two concerns with this type of heating. I'm not sure how the paints react to infrared when being applied, and I'm not sure how the surface will dry and cure if the temperature differential between the surface itself and the air above it is real great. I know Polyfiber has recommendations on temperatures and humidities for their products; you might want to chat with them. I'm not saying your method won't work, but you may have some logistics to work out. I'm considering a paint booth like this, but I want to continually force air into it, through some filters, and exhaust out on the other side of the booth somewhere. I was figuring on putting a space heater between the blower and the filters when it got cold, and let the filters be my fire arrestors. P.S. I don't hear a big boom unless you manage to shatter a bulb while there's still stuff suspended in the air. Cage the bulbs for me. +++ #4195 From: Benton Holzwarth Subject: Re: paint booth heat > Caution: The infrared heater emits infrared radiation (light) > that won't heat the air in the booth; it will heat what stops > the light it emits. This is what Russ was getting at, but it wasn't clear to me whether the heater in question was a radiant- or convection heater -- I've seen both kinds. Radiant heaters tend to be the element in the center of a parabolic dish type, while radiant heaters run more like hair-dryers, with the heating elements in some sort of forced-air duct. If his is a convection=type, it should be able to warm up a cube of air, tho' someone one pointed out the problems with stiring up dust, and the followup ideas to heat a wall/floor under the work and let it radiate up from there. (But note that if there's *no* air circulation in the paint-booth, the air will stratify surprisingly quickly.) One could also use a radiant heater, and a target other than the painted work to absorb and re-radiate the heat, but that begins to sound just a little Rube-Goldberg. There was also concern about igniting the vapors. I have no idea what a stoichiometric (sp?) mix would be for paint solvents, but would offer that while the ignition temp for an open flame is lower than for a heated surface (quartz element) there is still some temperature at which the paint vapor will touch-off. I wouldn't be surprised to learn that the quartz elements exceed that temp. Another thought, if using a heater inside a paintbooth: will the solvents blowing by the heater stick to and muck up the elements? It would probably not take very much 'tar' on the hot parts to ruin it. -- trivia: we sometimes use convection cooling in the instruments we make, where I work. Put a chimney around a hot IC, and it forms a natural circulation to expel the hot air and draw in cool air. But "convection cooling" doesn't work in space -- why not? +++ #4200 From: Warren "W. Shalm" Subject: Re: [Bearhawk] Re: paint booth heat I used to work in a shop when I got out of high school that had a downdraft Devilbis insulated paint booth, 10 horse exhaust fan and 680,000 btu gas air make up unit. It could heat the 500 sq ft room from -30F to 140F in 20 seconds (one air cycle). While this would be nice to have in the back yard, it cost more to operate in 1978 dollars for one winter than the price of a Bearhawk. The point is that even with the sucker pulling air and solvents away from the lights, the lights were encased in explosion proof cabinets. It only happens once in every 1000 times or so but I've become a believer in statistics since the lid of my BBQ went spinning out into the "back forty" a couple of summers ago. Couldn't believe it would happen to a nice guy like me (nice has nothing to do with stupid as I was licensed to handle this kind of thing). That's why they run those heavy copper ground wires on woodshop exhaust systems. Even if the bulk of the initial solvent "flash off" is cleared from the room, your going to have residual solvents released and can still be flammable in the right conditions (sort of like a home oil tank that is more dangerous when almost empty than a full tank of liquid). In short we were told horror stories by the safety inspector about the dangers of anything combustible mixed in the right proportions with heat and oxygen. (I just re-read this and realize that I'm starting to sound more like my father every day - another self-fulfilling proof of statistics) Along a slightly different line. For anyone that has oxy-acetylene tanks, I heard a story that convinced me that it's a good idea to chain them in the upright position. I know a guy who backed into a full oxygen tank that wasn't tied down. When it fell over it knocked the guts out of the valve and proceeded to take off like a scud missile. It went through a 12" block wall, crossed the parking lot, crossed the street, and slammed into a hill on the other side. Fortunately no one was hurt. ... now if we could just learn how to steer something like that ... +++ #4203 From: "dean robert cramb" Subject: shop heaters For what it's worth. when I built a dragonfly I was concerned with reaching the proper temperature as well as not blowing myself myself up with all the solvents I was using. I huddled with a few electricians from the pulp mill where I work and came up with this solution. I have two poultry heaters' these are heaters that have flash proof motors and the elements are like the elements on your stove' except they will not glow red. I pressurize and exhaust the shop with furnace fans. Has worked well for the last 14 years. +++ #4206 From: "Kent White" Subject: Re: [Bearhawk] paint booth heat > I'm considering a paint booth like this, but I want to > continually force air into it, through some filters, and > exhaust out on the other side of the booth somewhere. I was > figuring on putting a space heater between the blower and the > filters when it got cold, and let the filters be my fire > arrestors. Well, I wouldn't say this is the best thing, but it works. Putting a small auto radiator in front of the inlet fan safely heats the incoming air very well, and has been used to 0 deg with narsty isocyanates, clearcoats, and such finicky rubbish. The water system is closed loop to a small boiler or water heater nearby and has a thermostat inline. PS: Always wear a respirator, as a friend of mine could testify. He exited the foggy paintbooth into the prep room one time, and sneezed as he lit a cigarette. We lost a lot of sandpaper in that one quick burst. +++ #4562 From: Ken Beanlands Subject: Re: media blasters Don't be fooled in thinking that a slug of water does not affect the AFS water-borne stuff. That is exactly what I painted the fuselage and tail surfaces of the Christavia (and what I plan to paint the Christavia wings and the Bearhawk) with. Fantastic stuff. However, if you get a slug of water (it always seems to come in a slug whrn you disturb the hoses or change the spraying orientation) will need to be blotted off with a rag or it will leave an unsightly run in your paint job. It doesn't seem to affect the CecoFil that much, but it definitely hampers the paint. Back to your plenum. Where are your inlet and outlet with respect to the plenum? I've seen "Drip lines" where the pipe runs from ceiling to floor but the outlet tees off about half way down. >>> 4sep02 #9154-11297 +++ #9165 From: Del Rawlins Subject: Re: SAN-BLAST > THIS QUESTION IS FOR PAT FAGAN WHICH NOZZLE DID YOU GO WITH ON THE > SAN-BLAST UNIT AND DO YOU LIKE IT? I'm not Pat but I have what I believe is the same unit (TP 99S). Are you asking what nozzle size to use or what valve assembly? There are different sized nozzles and which one you use is probably best determined by the grit size of your blasting media. IIRC, I mostly used a 1/8" nozzle or whatever came pre-installed. As long as I sifted the larger particles out of the sand beforehand I didn't have any problems. For the valve assembly, there are two choices: the "38 special" and the "cougar" valve. You want to get the 38 special valve assembly. It is lighter and easier to service than the cougar valve, which is really meant for extremely high volume compressors. I used the 38 special valve with the tire shop compressor in Cordova, which I think was at least 7hp and ran at 175psi (but was regulated down for blasting and air tools) without any problems. I don't think I even wore out more than 1 nozzle and I put at least 6 large bags of sand through it. +++ #9171 From: "Pat Fagan" pfflyerz@c... Subject: Re: SAN-BLAST My blaster came with the 38 special valve as well, another reason I chose San-blast over the E-Bay seller. I like it, it is very easy to operate. Thus far, all I have blasted is airplane parts, mostly tubing, which still seems to take a long time because of the curved nature of the surface. I have some wheels for my '49 Chevy that I need to clean up but haven't gotten around to messing with them yet. The insides of the rims are extremely rusted and pitted and I have been curious how the blaster would work on them. I had some sand left over yesterday and tried it out on one wheel. Wow, cleaned it right up in about 20 minutes. +++ #9177 From: Del Rawlins Subject: Re: SAN-BLAST > Yeah, but how much steel is left for strength? I've intentionally tried to erode steel with a sandblaster before and found that so long as there is substantial material beneath the rust it takes some doing. With material that was thin to begin with there is some risk of blasting through or even warping due to heat buildup but I've blasted and painted lots of rims with good success. Certainly the rust that was blasted away wasn't contributing any strength so they aren't going to be substantially weaker after blasting. As a matter of fact, a sandblaster is the only good way I've found to repair a rusty rim. In the tire shop, we'd often clean the sealing surfaces with a wire wheel and reassemble the tire/wheel with some sealer, but also explain that it wasn't going to be a permanent fix since the rust always returned (it would not have been economical to sandblast/paint customers' wheels). When I blast my fuselage frame, I'll probably regulate the air pressure down lower than I would normally use, due to the thin material and the fact that I don't expect there to be very much heavy rust or scale. I ran my pressure blaster at 80-90 psig for doing autobody panels and the only blast through I experienced was due to rust that was nearly all the way through. If that is the case, you WANT to blast through so that you know to repair that section. "Boog" discovered several such spots when he blasted his super cub frame last year. +++ #9179 From: Budd Davisson Subject: Re: SAN-BLAST a thought on sand blasting new fuselages. it's not necessary to get an even, totally blasted surface on all of the tubes. All you're trying to do is get rid of scale and give the tubing a little tooth for the primer. Blast the clusters, but go light on the straight sections of tubing. Hold the blaster at an angle, not ninty degrees, so everything goes of at an angle with less impact. More important, just lightly skip across the surface, don't hose it hard looking for that even gray look. In fact, it actually makes more sense, and is much faster, if you just blast the clusters and Scottbrite the straight sections. Blasting all the way around tube is a pain in the butt, but you can wrap a Scotchbrite pad around it and have it nicely cleaned and roughed up in a third the time. +++ #9180 From: Del Rawlins Subject: Re: SAN-BLAST >In fact, it actually makes more sense, and is much faster, if you just >blast the clusters and Scotchbrite the straight sections. Blasting all >the way around tube is a pain in the butt, but you can wrap a >Scotchbrite pad around it and have it nicely cleaned and roughed up in >a third the time. That would probably work fine but since (as you mentioned) one of the purposes of blasting is to provide more "tooth" for the primer/powdercoat/whatever to adhere to, I would still be inclined to sandblast the whole thing. It will take longer, but since I'm only planning on doing it once, and sand is relatively cheap, I'd rather err on the side of overkill in the prep department. +++ #9181 From: Budd Davisson Subject: Re: SAN-BLAST don't forget what I said earlier: it's only necessary to lightly blast the straight sections. Don't hide the original surface under a gray, fully blasted area. It's unnecessary and increases the possibility of over-blasting AND don't forget that sand blasting actually can work-harden an area. +++ #9186 From: "Bruce A. Frank" Subject: Re: SAN-BLAST >Suppose it could be an advantage, but it'll probably be uneven and >slight. If there's a problem with it, it's the inconsistency. There was a place in PA when I lived there that blasted an entire fuselage in 5 minutes. The fuselage was set in the middle of a small room that had fixed nozzles all around the walls. The grit was fine crushed smelter slag (very fine but sharp like little bits of broken glass). The draw back was any flat sections of sheet steel tended to warp from heat generated even in that short time because of the tremendous volume. Tube fuselage always checked out as true to datum after blasting as it was before. I was joking a bit with my comment about work hardening. Bead blasting can promote surfacing hardening where sharp sand blasting usually does not. Glass beads beat the surface more than they remove material as shown by attempts to remove paint from steel with bead blasting....many times the paint actually burns rather than gets removed. Where as sharp sand cuts away the micro layer giving little chance for it to work harden. Bead blasting promotes surface uniformity in highly stressed items (which a fuselage is not) like piston rods... actually increasing margins before failure. The margin of a 4130 tube fuselage is many times what is needed for safety in this truss type fuselage. Even a little over zealousness that thins some tube is not likely to take the strength below adequate levels. Even punching holes with the sand blaster wouldn't impact structural strength. If it weren't for the need to protect the tube from rusting we could Swiss cheese the whole thing with a drill and it would just keep on working. The transition, in such circumstances where there is thinning, provides no abrupt changes that could be a stress raiser. Remember that it used to be that the best custom bicycles used tube that was very very thin in the center section and heavier at the butt ends for easier attachment (usually lug brazing, but sometimes TIG welding). (I know some bicycles are still made this way, but it is not promoted much these days) As Budd said, just food for thought here, not pushing for carelessness. +++ #9189 From: "TheStones" "TimS." Subject: Re: SAN-BLAST > if you just blast the clusters and Scotchbrite the straight sections. A quick thought, if you're going the paint route, you'll be using a primer base, so using one of the "etching" primers would provide the extra tooth while sidestepping the extra tedium of sandblasting the round tubing. If you're doing the powdercoat thing, then sandblasting the entire structure would be the preferred method. +++ #9785 From: "t18cox" "Bill Cox" Subject: Re: Bearhawk Muster 2002 > Do the HVLP spray guns that are run off the regular air compressor > work okay, or are they just a bit of a gimmick? I have been offered a > WALCOM HVLP with a gravity feed at a reasonable price - I'm not familiar with that brand, but we are using a DeVillbus HVLP that works fine. My neighbor is doing a Champ and shot a gallon of Polytone yesterday morning. Flow was very nice and there is minimal overspray to contend with. +++ #9787 From: "Pat Fagan" pfflyerz@c... Subject: HVLP What a timely time for this thread to come up. I have used a Binks spray gun for years and have been very happy with it. I just finished spraying the interior on #232. I used a whole gallon of Poly Spray on the interior and the doors. I shot a quart of Poly Tone and that managed to cover the interior and one door. The final straw occurred this morning while sweeping up all the overspray that had dried on the floor. It is time to seriously consider an HVLP unit. Bill, is the Devilbiss unit you use the type that runs off a regular compressor? I couldn't tell for sure from your post. Does anyone else have anything to say or recommend in this area? +++ #9788 From: Drew Schumann Subject: Re: HVLP imho, spend the $650 for the totally contained unit or find one who has one to borrow. I'd heard that there is a el cheapo unit out there, but can't find it looking casually. That way, the paint is sprayed on with heated air, which helps prevent some of the problems associated with HVLP. I just learned how to paint at school, and the HVLP unit we used allowed a newbie like us to learn how to put down quality paint in a matter of minutes. I'm still trying to figure out how to paint with the conventional gun, and frankly, I'm not that good. Painting with HVLP is like painting with a magic marker. I think my 8 year old could do a decent job of it. +++ #9789 From: "Bruce A. Frank" Subject: Re: HVLP While at SNF the Poly Fiber people spoke specifically against using their coatings with HVLP *IF* the air became heated in the pumping process. They recommended doubling the length of the hose to allow the air to cool before reaching the gun. Comments form anyone who has used a hot air HVLP paint system with Poly Fiber? +++ #9790 From: Hays Jeff Subject: Re: HVLP I have an Axis Citation, and have used it extensively with Polyfiber products, and the truth is it DOES NOT heat the air to the point of causing problems. As well the HVLP system DOES create a LOT of overspray when using it. I have had it and been using it quite a bit over a 3 year period. The truth is that you can get a quality paint job with any system, if you learn how to use the equipment. The difference in between my Citation, and my Sear's paint gun/compressor are minor. The really BIG difference, is that the respirator is a must for painting Aerothane, and other polyurethane's. So I'd still want the Citation. A couple things I discovered building my Kitfox. 1 - An airbrush like a badger is the most usefull paint device in the shop, for parts, stripes, etc. 2 - Aerothane requires a LOT of thinning to spray nicely. And isn't the tricky runny stuff people say it is. 3 - An HVLP system will turn the garage into London Fog after painting a piece the size of a wing ... So I don't know where the "low" overspray concept comes from..? +++ #9791 From: Benton Holzwarth Subject: re: HVLP > Bill, is the Devilbiss unit you use the type that runs off a regular > compressor? I couldn't tell for sure from your post. Does anyone else > have anything to say or recommend in this area? I've been trying to resolve what I'm going to do for corrosion control, and am zeroing in on PPG DX1791 as an alternative to DuPont VariPrime, which I don't think is available any more. Found two pages that had useful info on 'em, and more to the point, 'application' -- talks about using a cheapo Harbor Freight HVLP gun (sez it worked great, especially for the primer) and a subpage of had some good shots of his setup -- wire frames that he sprayed through to prime parts. I swapped some mail with him in the last few days where he mentioned that the PPG primer overspray 'flashed' before it'd settle on anything. Also, used '3M respirators for organic paint' ($20 ea; apparently more than just a charcoal filter) for breathing vs. a fresh air system, and a straight compressor-powered HVLP gun. +++ #9794 From: "rodsmith52" "Rod Smith" Subject: Re: HVLP I have a Croix HVLP sprayer system which I used for all the Polyfiber coatings and Aerothane finish coat when I redid the fabric on my Maule. This sprayer does heat the air that goes to the gun. I found that it did a wonderful job on the coatings through the silver coat. With the finish coat I had some orange peel texture that I could not get away from. Likewise with the Polyfiber epoxy primer. I had the same problem when painting some repaired panels on my truck. I thought it was just me, but since then have read that this is a common problem at least with the cheaper HVLP units. I will probably do some more experimenting with finish coat before finishing the Bearhawk. If I cant resolve the problem I will use a regular spray gun for the finish coat. It was my experience that there is a huge reduction in overspray with the HVLP which is one of its primary benefits. It is also more forgiving of operator technique. +++ #9796 From: "rodsmith52" "Rod Smith" Subject: Re: HVLP Yes to some extent, also thinned the aerothane to the maximum recommended. I haven't tried getting another length of hose which might help. Interestingly enough I recently painted an antique bathtub with a two part auto enamel and it came out perfectly smooth, no orange peel. +++ #9797 From: sonny cilley Subject: HVLP guns I went out and bought a $100.00 special HVLP from Sears to do the primeing on my wing parts and it seems to work well. I was actually amazed that I could do paint and look that good. I am not sure how it will do on the finish coat but what do you want for 100.00 . I am using the Poly fiber primer. piece of cake. I found a guy that is going to bend up all my spar material for both my main and rear spars this week.can't wait to get back to work on it. Sonny +++ #9798 From: "Bruce A. Frank" Subject: Re: Re: HVLP I hate to do this considering my run in with the owner of Poly Fiber, but recommended thinning may not be enough. In general, manufacturers have to limit the thinning of solvent based "paints" because of EPA's requirements for limiting VOCs. When I worked as a model maker for Edgecraft Corp I had exactly the same problems with both sprayed epoxies and urethanes. I called the manufacturers and was told there was absolutely no problem in thinning the paints until they shot properly. I had been worried that thinning these two part paints would impact their characteristics. That's when they told me that the limits on the thinning was strictly because of the volatiles released into the atmosphere. Try a sample. I'll bet that more thinning will make it come out perfectly. But please don't tell Poly Fiper I told you to. +++ #9800 From: Hays Jeff Subject: Re: Re: HVLP The big problem is that the air from the turbine is warm, and evaporates a LOT of the solvent. So to get orange peel free paint jobs you have to thin a lot. 40-50% thinning works well with aerothane. +++ #9801 From: "Bruce A. Frank" Subject: Re: HVLP guns > Thanks for all the info on HVLP. Unfortunately, I'm not any > clearer on what I should do than I was before. Don't give up yet. Try my suggestion of thinning the paint more than called for by the paint manufacturer. Shooting a tube fuselage with an HVLP system may not saved paint, but shooting large panels such as the wings and fuselage does put more paint on the surface than into the air (and eventually on the floor). I have been involved with side by side tests and we found HVLP saved 1/4 to 1/2 the paint used with a standard high quality high pressure paint gun. +++ #9803 From: Russ and Penny Erb Subject: RE: HVLP guns Yet another opinion--I've heard at least one person say if you already have an air compressor, use it with a regular spray gun. If you don't have an air compressor, get an HVLP unit. That is, don't buy an air compressor just to spray paint. +++ #9806 From: Drew Schumann Subject: HVLP equals less overspray I gotta tell you; I don't know much about painting. I picked up a paint gun for the first time last week, in fact. We had a large variety of guns to play with, just to get acquainted with what's out there. From this, I learned a few things to be taken with whatever grain of salt you want. 1. If you're used to painting with regular guns, you have to radically change your technique to get good results with HVLP. If an experienced painter says bad things about HVLP, I wouldn't trust their opinion. I'd get hold of some guns yourself and play with them a little bit. 2. If you're not familiar with painting, most folks can learn how to be good with HVLP long before the conventional guns. For one, you can't even see what you've done with the conventional gun until you're already past the spot you're painting. With HVLP, what you see is what you get. 3. There are a lot of phony HVLP guns out there. True HVLP is sprayed on between 2-10 psi. The Harbor Freight gun we've talked about sprays between 20-50 psi. What is Low Pressure about that? True HVLP has a great big hose leading to it. High Volume Low Pressure, get it? 4. If you're experiencing high rates of overspray with HVLP, you're either using too much pressure, or you don't actually have an HVLP gun. All just my opinion. Don't accept someone elses' opinion on HVLP without trying it yourself. I learned how to do acceptable paint in about 15 minutes with zero overspray with a quality unit. I still don't know how to do so with the conventional units, and frankly, don't ever care if I do. +++ #9808 From: "t18cox" "Bill Cox" Subject: Re: HVLP guns Sorry to take so long to answer your question. The HVLP gun I used Friday is a Binks 200 not a Devilbus. My neighbor has the Devilbus and they kind of go back and forth. It is used with a standard air compressor, not a turbine system. There is some overspray, but much less than a regular paint gun. On the average it seems to take about 60% to 70% the amount of paint as a regular gun for the same coverage. It took a gallon of Polytone to do the Champ fuselage and gear legs and there was very little paint powder on the floor. With a regular gun I would have swept a handfull for the same coverage. This is the third HVLP gun I've tried over the past 10 years. With the first I never could get an exceptable finsh although it was fine for primer. That's my experience. +++ #9809 From: "t18cox" "Bill Cox" Subject: Re: HVLP guns One other comment about the HVLP. Often I have a few parts to paint and will paint just inside the door of my 40x60 hangar. With a regular gun a quart of paint would fill the hangar with overspray even with the exhaust fan on. With the HVLP there is little apparent overspray more than 8 or 10 feet from the work. +++ #9824 From: Ken Beanlands Subject: Re: HVLP Same goes for AFS. The heated air will prematurely cure the paint and you end up with an "orange-peel" finish. They specifically reccommend against using an airless or turbine HVLP gun. I had a cheap Chinese knock-off HVLP gun that I bouthg for about $95 USD. It worked well but it had a problem shooting anything out of Vertical or pointing strait down. The vent in the top of the can also had a tendancy of getting stuck and needing cleaning in the middle of a shoot. So, as I'm just preparing to shoot the wings and ailerons, I went to a local paint sprayer manufacturer, Lemmer http://www.lemmer.com, and bought thier 2 qt remote gun. The 2 qt paint can hooks on your belt loop and the gun is free to move in any direction. They set everything up for me right on teh spot and tested the whole rig. Total cost was $300 CAD ($195 USD). Very high quality parts and service. +++ #9825 From: "n85ae" Subject: HVLP Voodoo You'd think from the posts that painting is a black art or something. The truth is, that painting is simple if you practice and learn how to properly use your equipment (whatever it is). As well a lot of people never mention rubbing out paint either. If you're willing to go throught the hassle of wet sanding and rubbing out the paint after it cures. Then you could probably paint with a a broom in a dust storm and get a show winning finish. +++ #9826 From: Ken Beanlands Subject: Re: Re: HVLP I don't know what the EPA is so up-tight about. I drank a full quart of paint solvent yesterday and no side effects. I gotta tell ya I love the AFS stuff. It's a 2-part water-bourne Polyeurathane. The solvent....pure water! What that means is that at least 1 part in 5 is very cheap and there is no worry of the paint exploding in the shop as the paint and catalyst are not flamable (neither is the solvent ;-). There are NO VOC's making the fumes totally non-toxic. It's perfectly safe to spray it in the basement wearing just a particle mask (to catch the overspray). So far, I love the stuff. It's ideal for the amateu builder. BTW, the rest of the coatings (CecoBond for gluing and CecoFil for fill coat and UV protection) are also non-toxic and non-flamable. The paint worlks equally well on fabric, steel, aluminum and composites with the right primers. If you're interested in more info, check out: http://www.aircraftfinishing.com http://www.spots.ab.ca/~kbeanlan/part15.html For those EAA members, login to the "members only" site and go to: http://members.eaa.org/home/homebuilders/building/painting/Rolling%20Poly%20Paint_%20%20A%20Spraying%20Painting%20Alternative.html +++ #9827 From: Ken Beanlands Subject: Re: HVLP guns If youreally want to save money and paint on teh fuselage, might I suggest you find a local contractor that does electrostatic painting. Typically, they come into a grocery store or office building and spray metal cabinets with no overspray at all. The gun produces a fine, low pressure mist that is positively charged. The frame is grounded with a strong negative charge. The paint is simply attracted to the frame. It will actually paint around the entire tube with one pass. In the end, it uses far less paint and produces a good finish. The only thing I would suggest is to use whatever paint that the contractor reccommends. They typically use an epoxy paint that is formulated for use with the paint system and will produce an incredibly hard, tough finish. Painting the entire frame cost me $150 CAD (less than the cost of the paint alone had I sprayed it) and took about 1.5 hours. There were a couple of small crevaces (like where the C-channel joined the tubes in the fin) that had to be touched up with a small HVLP touch-up gun. +++ #9831 From: "Greco, Bob" Subject: RE: HVLP guns I originally finished my Pacer with a Binks conventional spray gun used for automotive painting which gave me a finish sufficiently good to win a trophy at Copperstate. After suffering some vandalism which required a recover, I finished it using a Harbor Freight "HVLP" which was good enough to win a trophy at Antique Flyin. Both times it was finished with Stits Poly. The "HVLP" used less than 1/2 the paint than did the Binks and was much easier to use. Both used air from a standard compressor. The Binks cost over $250 while the Harbor Freight was about $60. I have since started using the HVLP on autos and cannot tell the difference between the Binks and the HVLP finishes and this includes using it on metallics and clearcoats. No question for me on the way to go. +++ #9837 From: Hays Jeff Subject: Re: HVLP Voodoo > I've got a hot flash: to some of us, painting IS a black art. Didn't mean to sound cavalier about it, I just have not found it to be so difficult. Here's a 10 point how I shoot Aerothane guide. This works for me, and I get pretty consistently good results. There's some pics of my wings just after/during paint at: http://homepage.interaccess.com/~jshays/latest.htm If you look, you'll notice I just paint in an open garage as well. The little dust nibs, etc. Are simple to get out with 1200 grit wet/dry paper and Meguiar's rubbing compound. So I personally don't worry about keeping a super sterile environment either. How I paint: 1 - Since 90% of the solvent evaporates in the air while spraying with an HVLP, you need to really thin Aerothane a lot. I thin it to the consistency of 2% milk. This works well for me. 2 - Adjust the spray gun, so that a quick trigger pull from 6" at a dry surface just slightly runs. 3 - Setup up some Halogen lamps so they're about 45 degrees to the paint, and so you're looking into the glare. 4 - Spray a light coat of paint, just short of "wet" 5 - If the surface is the size of a wing, walk back to the other end, and spray a crosscoat (just short of wet). If it's a small surface then wait about 5 minutes. 6 - Spray a "just wet" coat of paint. 7 - Go do something else for 40 minutes. 8 - Spray a "just wet" crosscoat 9 - repeat step 7 10 - Repeat step 8 & 9 once or twice more. Note: I built a roating wing, and a rotating fues fixture for my Kitfox. And I rotated the parts while the paint was setting up periodically to help fight runs. Definitions: Just short of wet - You can see a uniform coat of paint, but it isn't wet looking. Just wet - Spray till the paint "just becomes" wet looking, but no more than this on a vertical surface as it will run. On a horizontal surface you can spray more. +++ #9863 From: Russ and Penny Erb Subject: RE: HVLP I guess it's about time I weighed in on this one. Let me first say that I don't have, nor have I ever used an HVLP gun. I did not know that HVLP guns were made for use with air compressors. As most of you know, I'm using the Poly-Fiber waterborne coatings, such a Metal Prime. I've only used a standard spray gun, and done so with good success. I've also sprayed enamel on previous projects. One thing I can say for sure is that solvent based paints and waterborne paints spray differently. I can't tell you exactly what the difference was, but I remember setting the gun up differently. Seems the waterbornes had more viscosity, but I can't verify that. Based on your comments, I checked with my friends down at Poly-Fiber, and this is the response I got: "Yes there are HVLP guns that run off a compressor, these are really "conversion" guns and are most used by auto repair shops. They work great but are pricey. We still recommend good old Binks or Devilbiss suction guns that run directly off high pressure air for waterbornes. For what it's worth... Erbman's thoughts on finishing (not exactly the 10 steps budd asked for): 1. I hate painting. Always have. Too many ways to screw it up. I'd much rather build stuff than paint it. I can't think about varnish without thinking of creating a sandpaper finish from the dust that gets trapped in the varnish. At least waterborne finishes have solved one problem for me--I have to wear a respirator with solvent based paints unless I want a really nasty headache. Not a problem with waterbornes. 2. One truth I have found--90% or more of the quality of the finish happens before you ever pull the trigger. Preparation is everything. 3. To get the gun set up properly requires experimentation. That's what the walls of the paint booth are good for. If I can get a good result on the plastic, I can usually get a good result on the part. 4. Someone mentioned spraying light coats. I've found when the surface looks like it needs one more pass IT'S TIME TO STOP! Every time I gave into the temptation to spray one more pass I got runs. But, oh, the temptation is strong! +++ #9867 From: Ken Beanlands Subject: RE: HVLP Even a top quality "conversion gun" will only set you back about $300 USD and there are a number of them around $100 USD. typically you can save about 30% of the paint costs in the reduction of overspray. It also costs about $1000 USD on paint for just about whatever paint system you use. Hence, a savings of about $300. Your net savings (given that you would still need to by a standard gun at around $150 USD), is about $150 USD. I'm not saying that PolyFiber would do this, but isn't it interesting that the paint manufacturer is reccommending the spray process that uses more paint ?!?! +++ #9868 From: Hays Jeff Subject: RE: HVLP Voodoo I admit it's crude. BUT if there is enough paint, and the surface is sanded smooth with 1200 grit wet paper, and then wheeled out. It will look like a mirror. This is really my point. The only time the initial paint application makes that much difference is if you don't intend to wheel it out. I personally had a small moth land in the fueslage paint while spraying. I plucked him out while the paint was still wet. Shot a quick touch up blast, and after the paint cured sanded it out. The spot is entirely undetectable now. It took me a week of work to wet sand and wheel out my Kitfox, but it is VERY doable. I know since I have done it. +++ #9887 From: Hays Jeff Subject: Re: wet sanding, etc. You can most certainly rub out Aerothane. I know because I have. The solids in the paint do affect the ease of doing so. Red for instance is fairly soft and can be compounded with a medium/smooth compound, whereas white is very hard and requires a heavy cut compound to get it to shine. The white is so hard when cured, that I had to initially scuff the paint with 600 grit paper (dry no water) to break the surface prior to wet sanding with 1200 grit. Red on the other hand sands and polishes very easily. +++ #9892 From: "W. Shalm" "Warren Shalm" Subject: Re: HVLP Voodoo No one who is advocating mechanical "sanding and rub out" of paint has addressed a point that can totally ruin your hard work. With enamels and polyurethanes the paint usually goes on in layers (with each successive coat). The top surface has a surface tension much like water that forms a skin of a slightly different hardness. When you wet sand and buff through the top layer you can get a dull ring around the break through, which often won't buff out. The trick is to spray the paint on as smoothly as possible so that the sand/buff stage doesn't require cutting through that top skin. Budd's point is well taken in reference to spraying lacquer. Lacquers literally melt in to the previous coat and form a monolithic film. Buffing 30 coats of lacquer in a show paint job doesn't suffer with the problems of other paints as it has become a single film of paint. Some of the factors that impact the quality of a paint job are: 1. Surface prep - smooth, clean (of dirt, oils, silicones etc.), dry, lint free, compatible primer, proper sandpaper grit 2. Temperature, humidity, air flow, effective exhaust system (preferably a downdraft system that draws overspray away from the painted surface - overspray that settles on the surface after it has started to set up creates nibs and dullness) 3. Air pressure at the gun, air should also be dry (you can easily make an air line dryer), free of oil 4. Angle and distance of the gun from the surface, consistency of spray overlap, remember to smoothly trigger the gun at the end of each stroke (momentarily releasing trigger at the end of each stroke as the gun reverses directions to prevent buildup) 5. Quality of gun, size of spray nozzle, cleanliness of gun, gun settings 6. Setup time between coats 7. It is also helpful to wet down the floor to keep airborne dust to a minimum 8. And last but not least .... hold you mouth the right way. +++ #9893 From: "Bruce A. Frank" Subject: Re: RE: WD-40 > I don't know if any of you have had, or will have, problems with this, > but paint shop at Cessna begs us to keep WD-40 away from any part that > will be painted. Problems with WD-40 may be true, but these days most commonly available waxes and corrosion inhibitors contain silicone. I just automatically add anti-fisheye chemical (which actually is silicone) to the paint mixing process to eliminate the possibility. I have had a practise for years that any parts that I have just welded (steel) that is not going to get painted for a while gets a spritz of WD-40 to hold it against atmospheric humidity rusting (yes, even here in CA). These parts are getting the sandblast treatment and I have never seen silicone problems when painting freshly blasted steel. WD-40 seem particularly useful in preventing further rusting after a light haze of rust has formed....seems to provide some tooth for the WD-40 to hold on to. As for WD-40 as a lubricant for cutting, it works reasonably well, but I find the lubricating wax prevents blade load up (aluminum gets almost welded to the cutting edge...whether saw blade or end mill) a little better than such light lubricants. Aluminum "contaminated' with WD-40 during the cutting and machining process cleans up for me, well enough to paint either with rattle cans or powder coating, with a little wipe down with acetone. Our powder coater has never complained about lubricant left on parts delivered to him (unless they were actually dripping) so his wipe down method seems to handle it easily. Now if you are going to paint a fuselage that has overlapping sheets of aluminum I can see a seepage (from under the edge of the overlap) problem if WD-40 or some of the other anti -corrosion products have been liberally sprayed. What I have done to remove such possibility has been to wipe the seams with clean rags dripping with acetone then use an air nozzle blowing into the overlaps to push any contamination away from the surfaces to be painted. I then follow up with soapy water (plain dish detergent...no lemon scent or Aloe Vera to soften your hands) with a toothbrush scrub of the seams. Then another blow down with the air nozzle. I have never had a problem with fisheye or "holidays" when I follow this procedure before painting with either a high pressure gun or HVLP systems (or even the ubiquitous rattle can, to which I cannot add anti-fisheye.) +++ #9895 From: "Pat Fagan" pfflyerz@c... Subject: Re: RE: WD-40 I was going to keep it a secret, till the plane's roll-out, but since you mentioned WD40 I'll tell you of my recent experience. I just finished "engine turning" my instrument panel and I used WD40 as a lubricant. I then cleaned the surface with MEK and a surface prep solvent prior to spraying it with clear Dupont. There were no fisheyes. Had I read this post prior to spraying I would have been scared to death to paint it for fear of ruining all that work. I must say, the panel is Beautiful. +++ #9898 From: "Shannon" shanspur@w... Subject: Re: RE: WD-40 Thanks Bruce, Guess I was crying wolf. Probably Cessna has problems because of the seam overlap, plus we had to get rid of the acetone, MEK, Tooling dye remover and toluene. We are allowed to use the orange juice cleaner and MPK - methyl PROPYL ketone (why does adding one carbon atom change it from cancerous deadly to safe?). We also use WD-40 on cutting blades in jig shop, stick wax or Boelube on saw blades, paraffin or a selection of other lubricants on drill bits and taps. But we don't have to worry about getting a 6 million dollar paint job. I really don't know what causes the problems for paint shop, but they sure scream bloody murder about WD-40. Maybe they're just too lazy to do a good prep before shooting.... +++ #9901 From: "Kent White" Subject: RE: RE: WD-40 Both MEK and acetone are toxic, and very bad for the liver, according to the two research chemsists (PhD) I consult with. Upon contact with the skin they are immediately absorbed into the body. Their recommended cleanup solvent for many applications, one which I have found to be quite effective BTW, is isopropyl alcohol. It is cheap and available and cleans up well after fibreglas, too. Paint stores do not make enough money on it, and so continue to sell the toxics. I have found "smoothie" effective for silicone as well. TSP, trisodium phosphate kicks silicone and grease quite effectively, too, and is cheap and fairly non-toxic--wear gloves. I painted high-end stuff for quite a while, though nothing worth over $250,000. +++ #10248 From: Drew Schumann Subject: Cheap HVLP experiment Well, tried out the $59 HVLP unit today. I'm finishing a sampan for my kids and I to explore rivers with. I used some 6 year old exterior latex, (Hunter Green, if you must know) and thinned it with plain old water, until it ran about 18 seconds from the Zahn cup supplied with the unit. Frankly, it performed better than I expected. It puts out a LOT of air at a fairly high volume. (48 cfm @ 4 psi) I had good coverage, with very little problems with the paint. There is a little problem if for some reason you dwell on new paint. It tends to ripple the paint just sprayed on, which is to be expected. If I kept moving, it put a satisfactory and smooth protective coat on what is otherwise a pretty rough looking boat to begin with. Due to my experience, I plan on putting on my two part epoxy primer with this gun if not the finish coat on my airplane. It's available at Harbor Freight every day for $99. It helps that I don't have to worry about moisture and whether my el-cheapo air compressor can handle it. Some times it goes on sale for $79, but if you wait, it will be on sale for $59 sooner or later. The next cheaper unit like this I've seen is $650. Your $59 buys you a turbine, carrying case, 3/4 inch hose and a plastic paint gun with decent metal parts, Zahn cup, and maintenance/cleaning wrench. All you need to paint in one unit +++ #10251 From: Ken Beanlands Subject: Re: Cheap HVLP experiment Another good quality gun is from Lemmer (www.lemmer.com). I just bought one with a remote 2 qt. cup and I absolutely love it. The 1.5 mm tip is a little large for waterbornes, but there is also a 1.3 mm available. Of course, it helps that thier head offices are here in town! +++ #10429 From: "Pat Fagan" pfflyerz@c... Subject: HVLP update First off, congratulations to Tom on the first flight of 075. How could you not think that would be a big deal? Thanks to everyone for all there input on HVLP equipment. After much consideration I elected to purchase an HVLP gun that was powered by my existing compressor. I bought a Sharp 998 which has a pressurized pot. That is nice since there is no need for a syphon hole, so no chance of drips. I found it sprayed Poly Brush and Poly Spray just like my old gun but the real test would be the color coat. It didn't seem to use any less material, but after I finished the first session I noticed a significant lack of overspray that needed to be swept up. Also, the overspray cloud was never evident. I mixed up my first batch of Aerothane finish color this morning. At the maximum cup pressure of 10 lbs, the paint atomized like stucco plaster. Since I had stupidly neglected to purchase any reducer I decided to try my old gun. With the pressure cranked up to 50 lbs the paint atomized OK but I just couldn't bring myself to use it. I had visions of wasted paint and blowing off my masking when I got into spraying the fuselage, and the noise. The light sound of the HVLP is very seductive after you have tried it. After a fast trip down to Aircraft Spruce for some reducer I switched back to the HVLP. With about 30% reduction I got good atomization and good flow. Bottom line, I am sold on the Sharp HVLP gun. Harbor Freight had a sale on an HVLP gun with a 2 liter pressure pot. I bought the thing to use the pot and will use the gun to paint things around the house. +++ #11083 From: "Corky Scott" charles.k.scott@d... Subject: Cheapo HVLP unit I promised that I would get back to the group with a performance report of the little cheap Wallmart/K Mart/whatever HVLP unit once it had been tested by a professional auto body guy I know. He told me that it sprayed tolerably, but that he felt he could get a better job using his own guns which are all of the high pressure siphon cup variety. He asked me specifically what I would be spraying, and allowed that using it on the tubes to spray primer would probably be the ideal use for it. He's unsure of how it would fare when applying a color or top coat. So as in many things the answer is a sort of "not sure". It will come in handy to spray primer but I may end up using my regular high pressure gun to apply color coats. This means I'll have to score a compressor, as my old homebuilt compressor (four cylinder walk-in freezer compressor) is making bad noises and prone to seizing when run for long periods. Lots of compressors on E-bay. +++ #11086 From: Ken Beanlands Subject: Re: Cheapo HVLP unit A lot of the performance of a particular gun is defined by the material you run through it. For example, running house latex through a high pressure siphon gun will most likely have poor results. The system I used employs a 3-part (paint, catalyst and Hydrogen dioxide;-) water-bourne Poly Eurathane (very low toxic fumes and the overspray will not burn/explode) which pretty much demands an HVLP conversion type gun. The turbine type are too hot and the paint dries before getting to the surface. High Pressure guns apply too thick a coat. I've used both a cheap, and a moderately expensive gun. The cheap gun actually worked better than the expensive one. It's also nice to paint the entire plane in 3-4 gallons of paint. +++ #11093 From: "Pat Fagan" pfflyerz@c... Subject: Re: Cheapo HVLP unit A further update on HVLP equipment. I went for a good quality Sharpe HVLP gun and have been very happy with it. However, I got numerous runs in my base coat do to unfamiliarity with Aerothane and finally decided the best solution was to sand them out and reshoot the whole thing. I did just that last week, using the HVLP gun and the cheapo pressure pot from Harbor Freight, the same set up I used the first time. I didn't feel I was getting enough material down on the first two passes, but was also trying to avoid runs. While shooting test panels prior to my third pass I discovered that I was definitely not getting enough fluid but no amount of adjustment or cleaning would help. I ditched the pressure pot and put on the siphon cup with no improvement. I ended up switching back to my old pressure Binks to finish the job successfully. I don't know yet what went wrong with my Sharpe. Bottom line, I still like the HVLP for its lack of an overspray cloud and the gentler spray in corners and on masking, but either one will do a good job. +++ #11102 From: Drew Schumann Subject: Re: Cheapo HVLP unit > What ever happened to the discussion about the HPLV gun sold at Harbor > Freight? Ooops, I tested it and forgot to update you guys. Using household latex, the "el cheapo" which is chinese for "helping american's fund their greatest enemy's military" hvlp gun worked terrific. I also used it to spray rustoleum on my '78 Dodge 4x4 and all I have to say, is that it is very appropriate for that type of vehicle. It tends to glop paint on and leaves a slightly textured finished. As far as hvlp and aircraft paints; at our school and in our instructor's private shop, he and we use hvlp to put on polyurethane all the time with the "turbine" type unit. It does a beautiful job. I don't know what's happening with other folks who are not having luck with turbine-type hvlp (Which, imho is the "real" hvlp). I suspect the problems stem from folks who are familiar with regular pressure-type paint guns who are not using correct technique or something..... +++ #11111 From: "Corky Scott" charles.k.scott@d... Subject: Re: Digest Number 880 > The turbine type are too hot and the paint dries before getting to the > surface. Hi Ken, a trick I read about to prevent this from occurring is to lengthen the air hose leading to the gun by a factor of at least two. This allows the air from the turbine to cool down some thus preventing the situation you mention. +++ $Id: 3.1.7-Tools-Painting,v 1.8 2002/09/05 04:57:02 bentonh Exp $