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GO TO Protek Performance THE RV-7 AIRCRAFT BUILDING THE KIT e-mail: robert@protekperformance.com
OTHER USEFUL SITES Project started 8/15/01
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The Priming Issue This is a hotly debated topic that you can find much commentary on. After reading a lot of opinions, and doing some priming myself, both with rattle cans and a spray gun, I have settled into the following conclusions. I have found there are three types of areas on the plane that require different coating considerations. There are parts (such as skins) that are alclad coated, that require no coating at all. This would include the insides of skins that will never be seen again. There are non alclad parts that require corrosion protection, and there are areas that will eventually receive a color top coat - the "paint job". You will find opinions from people with little experience and opinions from people with tons of experience. If you can pay attention to the latter group only, you are half way home. The experienced people seem to all agree that alclad parts (like skins) do not need any further corrosion protection, unless you are going to park the plane outside, next to the ocean. In other words, the insides of skins do not need to be coated. The next group of parts are the non-alclad parts that will not receive a color top coat in the future. These are parts that end up sealed up inside structures, like the skeletons of the empennage. Some of these parts are alclad. For the sake of simplicity, I grouped all non-skin parts into this group (even if some of them are alclad). I coated all these parts with NAPA 7220 self etching primer. This product is easy to use and can be purchased at any NAPA Auto Parts store. The 7220 dries to the touch in about 10 minutes. I simply washed the parts in warm soapy water to clean them before spraying. The final group of parts are those that receive a top coat of paint. These areas include the outside of skins and the cabin. These areas need a good base primer for proper adhesion of the final paint. I am using Dupont Variprime for these areas. The Variprime is a two part, self etching, epoxy primer. This product will supply a good base for a quality final finish such as a polyurethane enamel color coat. For small parts I have used a $30 touchup spray gun from Home Depot to shoot the Variprime. This has worked well and is easier to spray than the rattle can primer. The downside to the spray gun is the mixing process to get started and the cleanup afterwards. It is best to spray several (many) parts in the same session so that cleanup is a small percentage of the project. There are many other similar and suitable primers out available. There are also many other opinions available on this subject. But I think the above procedure will provide a quality result for most planes.  |