Composite Paint 1

[Stache]

A question for the composite guys. As I understand composites and UV don’t mix. So is there a certain type of paint that should be used over composite material and why? The questions has come up about paint touch up not using the original paint the manufacture used is there a difference or is most paint used on composites capable.

Stache

 

[berkshire]

Stache
What I am getting from your question is that you want to use a paint other than that specified by the manufacturer.
There are no certain types that should be used.In practice epoxy paint has been used as a primer because of its adhesion qualities.
Most opaque paints will give you good UV resistance the clue here is that if you can see light through the paint it is not opaque.
Epoxy paints can be purchased to meet MIL SPECS such as P23377D in case you also have to paint ajacent metal structure They work well as primers over composites although the Strontium Cromate is not needed by the composite. Epoxy top coats tend to yellow and chalk over time. It can be quite a shock to do a repair on a white aircraft to find the paint has turned cream and your paint will not match.
Linear polyurethane paints tend to have the best track record for durability and UV resistance, they are also the most expensive,my favourite is Sterling.
One rule of thumb is to look at the inside of a composite panel,if you can see light shining through, then some UV is getting through.Of course this will not apply on a carbon panel.Let me know if this helps.
Brian Evans.

 

[FieldTeam]

Just an additional thought....some paints have better resistance to chemicals they might come into contact with, such as skydrol.