smacfe
Posts: 61
Joined: 11/25/2003
From: corona del mar,
CA, USA
Status: offline
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I switched to Valspar for a number of reasons - mostly related to my flaky work ethic. At times I work away like a demon and at other times, the plane may wait up to a month while I am off doing other things. As such I cannot guarantee a co-ordinated succession of steps or coats. The primer I was using was K36/K200 which works OK if you sand it within a short time window - usually 14 hours is ideal. After this the primer gets harder and harder where after 36 hours it is like sanding stainless steel. It is also gray, which is a terrible undercolor for orange - a favorite color for my decrepit eyes. The Valspar primer comes in any color you want, but the standard is white. It is ready to sand in minutes but gets no harder after about 4 hours and can be easily sanded months later. It is also very flexible so it will never get brittle - which is why some primers may pull off with tape after a while. While I don't believe that primer should be used as a filler, the Valspar primer can also be sprayed heavily enough to fill the odd pinhole that you miss with the spackle. The Valspar primer goes on like the K36 in that you can spray it heavy or thin it out a lot and it still goes on nicely and resists running even when heavily reduced for that final velvet coat. This works nicely for me as I my first primer coat generally gets almost fully sanded off and I put a second extremely thin coat as my paint base. I also refuse to pay for high priced reducers and thin all my paints with acetone.
Valspar makes both a single and a two stage paint line. I use single stage exclusively - again because I cannot be sure when the plane will get the next coat. Two stage paints are often pretty critical about how long you wait between coats. Single stage paints are much more durable as each coat is fuelproof. The downside to single stage is that you have to color sand between colors - or coats of the same color if you wait too long. I sand with 320 grit wet between colors. As far as the color goes the Valspar seemed no different than the Jet-Glo I had been using so I will continue to use my supply of Jet-Glo until I run out. It also sprays and covers well with an HVLP gun so less paint is used.
As for the clear, I was looking for a new clear as the Jet-Glo clear, while very user friendly and easy to spray at different viscosities, had an unacceptable level of gloss. The PPG clear which I used on my Loki had a very high gloss but was very critical as to how much reducer was used, and required a PPG reducer to be usable at all. It would only spray well within a very small viscosity range. It was also very unforgiving to spray technique and would run at the slightest mistake. The Valspar clear is slightly more difficult to spray than the Jet-Glo, but enormously more user friendly than the PPG. The gloss is much better than the Jet-Glo, but not as high as the PPG. The Valspar clear is also happy with acetone as a reducer (about 25%). The Valspar clear also sands really nicely. I clear all masking and put two dustcoats over all paint edges then sand with 320 wet to eliminate any perceptable paint lines. I have never been able to get an acceptable clear coat with an HVLP gun, but find that the perfect gun for clear is the Harbor Freight detail gun. They go on sale from time to time for $9.99 and I always buy one as after repeated cleanings the chrome plating on the needles begins to come off. I get at least 5 airplanes per gun so at 10 bucks a pop, I toss them and break out a new one every 5 airplanes. With this gun, I can get an almost flawless finish coat right from the gun requireing no further work. Although I got a really cool mini buffer from Tom Scott, the finish on this plane won't need it.
The Valspar paint is about 20% less expensive than PPG and about 50% less than Jet-Glo, but money was not the issue here as I was looking for an easier way to get a better finish than I had in the past. The fact that it cost less is an added bonus. In summary, I was very pleased with the Valspar system. It produces a very nice finish and is very user friendly and forgiving. I have yet to see if it as durable as the Jet-Glo which sets the standard for durability.
As for paint prep, I use the Lyle Larson system which I slightly modified. First, I wash the parts with a soap/degreaser/wax remover and water cocktail. Then I sand non gel coated parts beginning with 150 grit, and gel coated parts with 220 grit. working down to 320. Then I wipe them down with acetone and using compressed air blow off the surface facing the blow gun directly at the surface at 90 degrees. This should blow open all the pinholes in the surface and make them visible. Then I use the cheapest spackle/joint compound I can find and stick my hand in the bucket, grab a handful and slather the parts with spackle - pushing it hard into the surface as best I can. I leave a nice even layer of spackle on the airplane and let it harden. Then I use 150 grit and sand ALL of the spackle off. At this point the spackle left is that which is in the pinholes. You must resist the temptation at this point to blow on the surface of the parts and LIGHTLY but copmpletely wipe the surface with a non-linting paper wipe lightly soaked in acetone. At this point, you cannot wait more than 15 minutes gefore spraying on the primer - so don't sand the spackle unless you have the time to get through the first sprayed coat of lightly thinned primer. If you notice any pinholes, respray them and smush (technical term) the primer into the pinhole with your finger. Zap it again with the spray gun. When you now have adequate time, sand off the entire first coat of primer, take an x-acto knife and clean out all hinge lines, wipe down the parts with a non-linting paper wipe soaked with acetone and IMMEDIATELY spray a thin coat of primer. This coat should be just heavy enough to cover and no more. Since this was an extremely thin coat of primer, you now should sand with 320 grit wet, only to smooth the surface - you could even use 400 wet as you do not want to cut through the primer. Once again, wipe down the parts with a non-linting paper wipe soaked with acetone and immediately spray the first coat of color. Since I use only single stage paints, I have learned to finish one color, let it dry, then color sand and immediately apply the next color. While not an expert with two stage paints, I understand that you should not allow too much time to pass before applying the next coat or color.
I have also learned to be a fanatic about tape. I use only the green 3M #233 tape for genreral masking and either 3M 1/8" fineline plastic tape or a special plastic tape from Germany for fine line masking. The 3M green tape is specially formulated to not react with partially cured polyurethane paints (what we use) and to also leave absolutely no adhesive residue when removed. I absolutely refuse to allow the blue tape anywhere near my planes. I am careful to run my fingernail over the entire masked edge to ensure that there is no paint seepage under the tape. I keep all my paint masking tapes in a sealed box. Pick that old roll of tape off your workbench and look at the side. See all that gunk stuck to the side of the tape? How can you get a clean line with that sludge on the edge of the tape? Also, even though there is supposed to be no adhesive residue from tape, I carefully wipe down taped areas with Goof Off then acetone to ensure no tape residue.
Another thing I learned is to use only non-powdered nitrile gloves. Although the powdered gloves are much cheaper, the powder has a very negative reaction with the clear, and will cause it to crinkle as it cures requiring you to sand it all off and start over.
Hope this all helps.
Scott
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Proud Bird II - 
