I am talking about say 1cm x 1cm.
Normally I scrape these until no corrosion is left in the metal, and obviously avoiding the use of steel wool because that creates fresh corrosion.
Then I prime them with 2-pack epoxy primer.
For small bits it would be fine to leave it like that, especially as the white primer is close to the main aircraft colour.
But I find the stuff (expensive aero stuff) discolours and disintegrates in a few months to a year. Presumably it has poor UV resistance.
If I want to avoid the whole proper job of using
primer
base
lacquer
like Socata originally used (and all of these are 2-pack polyurethane paints from MAPAERO – a horrible company to deal with), what is the best solution which will last?
One can get 2-pack white epoxy paint which should be compatible with the 2-pack epoxy primer I use, but won’t the UV resistance be rubbish too?
Maybe the UV resistant lacquer cannot be avoid after all. Certainly that is how cars are touched up (2K isocyanate paints – have done that too, spray, with pretty fancy breathing gear).
One-pack paints on the retail scene (e.g. the common spray cans from car parts / DIY shops) tend to be of poor quality. I do have the MAPAERO stuff but it needs a compatible primer, and has a poor shelf life.
Hello Peter
I am sure you can find this in the UK as well We use a paint supplier to put the same paint as you would use if u paint the whole plane in spraycans that have 2 chambers
1 for the paint and 1 for the hardner by pushing in a rod the 2 componants mix and u can use it (oviously needs a good shake before use) u can use it only once as the hardner will dry up inside and get hard after being mixed
I also would get a “scan” from a cover panel or similar so they paintshop can mix up the right colour in tone as coulour might have changed over the years due to UV etc.
if u want anly to paint a small area 1 × 1 cm you can also use the same paint as above but notin a aerosol just in a small tin with some hardner to mix (be aware that here in Germany initial the will sale only water based paint to you as theis is for enviroment reason but if u say it is for a airplane or historic car they will sell you the “old style” paint (also like this no clear coat required)
brush the paint on the area u wont to touch up with a special paintbrush for touch up and let it try repeat a few times to have a"solid" new layers of paint (make sure it is all proper hardend etc)
than rub it down with wet and dry starting with 400grade than 600 grade and than 1000grade try to have the “new paint area” as flat as the paint arround it
finally buff it with a “3M type grind and polish” past with a airbuffer or electrical buffer with SLOW speed
u should have now a next to perfect look and finish
hope this helps
PS just be aware that modern car paint is NOT the right thing as it is mostly waterbased and need clear laquer
Peter wrote:
One-pack paints on the retail scene (e.g. the common spray cans from car parts / DIY shops) tend to be of poor quality
The often reported “poor quality” is actually in the amount of pigment. They are made for “touch up” and therefore do not have large amounts of pigment to be able to blend in better.
If that primer of yours is the same color as your main aircraft color, you can simply put a clear coat of 2k PU (from spray can) on top, or a 2k PU pigmented from spray can. I think these are only acrylic PU, but still PU.
I use industrial paint, 1K modified PE on my Onex (as trimming to the polished alu). This paint is dead easy to put on, work as primer and top coat, and will protect anything for ages. It is especially made for protection/coat on oil rigs in the North Sea, and is certified for it. The only down side is the price and it takes 2-3 weeks to obtain full mechanical/chemical strength (it is dry to touch in less than an hour). Also, it is not glossy, but that fits perfectly with the polished (and highly glossy and shining) alu.
Regarding paint, I don’t think I have seen any area where there is so much confusion and crazyness. It seems like everybody has to find their own solution that works, and stick to it. So I will not recommend anything, I only say that the modified PE North Sea stuff works for me for the time being
Many thanks for the feedback.
It’s a very good point that I could just use a clear UV lacquer on top of the primer. The Q is which lacquer would be compatible with the 2-pack epoxy primer. For example standard car paint spray cans are not; they bubble up on contact with the epoxy.
Is there such a thing as a 2-pack UV resistant epoxy lacquer?
I emphasise this requirement is for “quick and dirty” touch-ups. I do have a proper spray gun, and a compressor / scuba cylinder + regulators for where a compressor is not possible / not allowed, but that is a lot of hassle, a lot of work spent cleaning the equipment, a lot of solvent wasted washing everything and spraying through the gun to clean it afterwards, and a lot of overspray precautions. Plus, for 2K especially, a full face mask etc. The results can be amazing but it isn’t practical unless you have a lot to do. I want something which can be mixed up in little measuring jars and brushed on. The 2-pack sprays I have seen have a very short shelf life, and I have not come across ones where you mix the two parts manually (like in a Semkit dispenser).
brush on should be fine and than u can rub it flat to match with the “old paint” just make sure u dont have any “sharp” edges with the old paint
for cosmetic repairs i have also used “fablon” self adisive vinyl and I had that “painted” in the coulour i needed it can be also a solution for visual apperance just had the alloy primed before
Peter wrote:
The Q is which lacquer would be compatible with the 2-pack epoxy primer
You just have to try and see. The general rule is to use the same “system” of primer, paint, etc, but that is easier said than done for repairs of old planes. Also take a look at boat paint. Lots of different manufacturers, but as opposed to car paint that is 100% spray, boat paint have smaller boxes (1/2 l or even 1/4 l) of 2k PU top paint maid for brush, roller or spray, very durable and you can mix tiny batches. Epoxy is not UV resistant, PU is.