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Originally Posted by Fordestes
What kind of prep is needed for water based paint? is it ok to shoot water base on blasted (wet) metal after cleaning without creating adhesion problems? would prepping with Methyl Ethel Ketone solve any moisture entrapment issues? it seemed to me that M.E.K may be somewhat water soluble and dries quickly .
what about using flex agents for frames? I had problems with a frame primed with an etching primer when put into service the top coat began to crack and peel. the PPG rep said I should have used a flex agent. I never heard of such till this happened . are there paints formulated for frame/metal flex without using such additives?
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Honestly, i know nothing of water based finishes. I will never use them unless they quit making others. You should not have to use a flex agent on a frame. I know they flex but paint should have good enough adhesion to "go with the flow" of a bend.
Stick with epoxy, then a nice workable/sandable 2K primer, then top coat with a single stage urethane or base coat / clear coat. These products in my opinion, together, create such a fantastic durable finish...I have sprayed hundreds of gallons of this combo and seldom ever had a problem (this isnt an exaggeration). If i did it was an oil contamination, from what exactly, i cant pinpoint. Ever see a car with a huge dent in the door and the paint doesnt have even a crack or even begin to fail? Good prep and quality paint is the answer to great adhesion. Avoid wiping parts with lacquer thinner or acetone before painting. Use something like prepsol.
Cracked catalyzed top coats normally are from over thinning. Use the mfg.'s recommendations. Some people have a gun that cant break down a paint so they thin it more to make it "flow". Over thinning traps solvent and as the paint dries it shrinks but shrinks after the surface of the finish has started to cure.
These (pictures) were sandblasted and primed the same day with epoxy, they 2 coats of 2K. Dried then sanded smooth with 500 without water, just dry paper. Then 2 coats of single stage urethane, wet on wet. The gun is an EURO FLG-5, I have several spray guns, some were $1000 or more. This gun is the best out all of them in "my" opinion. These are all 2 coats off the gun. No sanding between or buffing.
The truck i painted about 10 years ago. It needed a lot of body work. I primed the truck with 1 coat of epoxy then the urban camo was done with base coat clear coat, no flex agents. About a year after paint someone hit it at the grocery store. You can see how far metal can bend before the paint pops with good adhesion. It hard to tell but the dent is about 3" deep. It also is holding back rust well as this truck sees salty winter roads...