Ask the Expert Question-and-Answer Archive

by Ron Joseph

November, 2003

Paint System Change on Aircraft Skin

Q. We would like to use the Akzo Nobel's Eclipse High Solids paint system on our Fokker aircrafts. This consists of the 10P20-44 High Solids Epoxy Primer, and the Eclipse High Solids Polyurethane Topcoat.

Our main goal is to use the same paint system on the MALÉV's whole fleet. Our new Boeing 737-6/7/800 aircrafts and Bombardier Regional Jets are also use the same Eclipse system, but our Fokker aircrafts were applied with wash-primer exterior coating system (Aerodur Primer S15/60, Epoxy Primer 37057 NF, Aerodur C 21/100 UVR finish).

Is it possible to change from that wash-primer system to the High-Solids Eclipse system? Can we remove that wash primer from the skin? As the brochure says Eclipse primer's needs an alodined surface only. I heard that this High-Solids systems are very sensitives to contamination.

The process manual says we can remove that wash primer with Scotch Brite and some kind of solvent(?), but it needs a considerable job. What do you think, we can apply the Eclipse system without removing that wash primer, or the Eclipse primer's will think that the remaining wash primer is a kind of contamination?

A. You might be able to apply the Akzo Nobel Eclipse Epoxy directly over the existing wash primer because by now the wash primer is old and the acids have probably already dissipated. If you remove the old coatings all the way down to the wash primer and then do a thorough wash down of the aircraft, it is possible that you will get the adhesion you require. On the other hand if Akzo Nobel insists that they do not want any wash primer, not even the old wash primer, then you will need to remove it with Scotch Brite or with a chemical paint remover. The advantage of Scotch Brite is that is will roughen up the surface and enhance the adhesion of the epoxy to the Alodine.

On future aircraft I presume you will simply use the Alodine followed by the Eclipse. But I am fairly sure that if you thoroughly wash down the existing wash primer with water and then allow the skin to dry, you should have good adhesion with the Eclipe.

If I were in your shoes, I would confirm this in writing with Akzo Nobel and also perform some tests in non-critical areas.