Zinc Cromate

Two things, is the part clean? The oils used to coat the mold before plastic is injected does stay on the surface of the plastic and will deter paint from sticking.

Also did you mix your paint thoroughly? Getting all of the components to resuspend is a must.

How are you applying it? Brush or airbrush?
I've found that it normally covers pretty well when airbrushed but if the mix is to thin it can be as bad as white or yellow to apply.

Im saying that the Testors square bottle stuff fas not going on very well, I can see the base coat beneath it and its not leaving a good finish, sorry for not being very clear.

I like the Mr Color #351 which I sourced from Sprue Brothers.

try a custom mix:

15% flat green and 85% flat yellow. There seems to of been a few shades of this mix and a greener looking version. for that I would try 30% flat green and 70% flat yellow.

Yes, please define what you mean by better.  Also, there is Green Zinc Chromate & Yellow Zinc Chromate, both used on US Aircraft.  If you're refering to the small square bottle Testors enamel, it''s a close match to yellow Zinc Chromate.

Regards,  Rick

Try Mister Kit acrylics, both the green and yellow chromate. Good hide, good adhesion, easy to use. But don't apply a mineral spirits wash over them. Seal with Future before the wash.

What do you mean by better?