Painting aluminium: zinc chromate primer vs self etching primer

[david moore]

Stuart

Phosphate pretreatment works very well for Al - used in the car industry same as for steel. All Ford trucks have had Al hoods for 15 years at least and no paint adhesion problems. Puts a micro layer of phosphate crystals on the surface which give great adhesion. While I was in the States I used a Blue Lightning phosphate product - not sure of brand names here in Canada. You only need to brush it on or dip. Surface has to be thoroughly cleaned first of course. The yellow or green chromate is great but hexavalent Cr not allowed any more at least in the car industry. Maybe the aero folks are still allowed to use it.