Etching primer?

[LudicrousSpeed]

In all the posts I have read here, I have never seen anyone speak of etching primer for bare steel. What process does everyone use? Epoxy primer to bare steel?

Also, did I misunderstand about the use of fillers over epoxy primer? Do you use actual bondo type fillers or are they the two part spot putty, like Icing?

Thanks! /ubbthreads/images/graemlins/yay.gif

 

[rex]

There's alot to this question.I use PPG epoxy so that throws a big ? in it for some because it's a unique product,more geared to the resto industry than anything else because of it's slow drying and long 'open' characteristics.Basically,bondo or the 2 part putties are best used nowadays over a sound substrate over the bare steel-ie:a sanded sound finish is better than grinding to bare steel if possible.The older products wouldn't tolerate this but the newer muds and putties stick much better with less chance of rust contamination down the road over a bare,ground steel or aluminum.

 

[rex]

Wow,that post was confusing.You can mud over HOK epoxy and I imagine anyone else's if you let it dry and rough it up with 80 or 120 grit.PPG's can stay open for up to 3 days without needing any sanding for topcoating but it also means it's soft and will take a few days to stop moving around and shrinking.I rarely use etch primer just because it's so humid here I've watched it suck up the moisture and turn orange before it can be topcoated.The good ones add corosion protection but then again a good epoxy has enough corosion inhibitors to not worry about it.