Sending 2 cars to the blaster to clean the floors. He did the '70 Chevelle recently with soda and touched up with sand in places showing surface rust, but these two are worse and he says he'll pretty much have to sandblast the whole underside. What's next? He neutralizes soda, but doesn't know what to do with the silica before etch prime.

Just blow it off with clean (oil free) air and get it in prime ASAP. It's as clean as it can get post sand blasting and any kind of prep will only risk contamination.

Tom

I'd first wipe it down with some wax and grease remover, you will be amazed at all the dirt that will come off even on clean appearing metal.

I'd first wipe it down with some wax and grease remover, you will be amazed at all the dirt that will come off even on clean appearing metal.

You can bury dirt under the primer but not silicone. Many rags and shop towels contain silicone and that is the last thing you want to be wiping on the bare metal. If it's there at the beginning it will work it's way up to the top coat or clear and ruin your day. Been there, done that and know enough now to leave it alone.

Tom

So if you sandblast something to bare metal, this step is a waste of time? If so, this is a step I'd love to skip.

Baking soda is the last you want to strip a car with it leaves an oily residue that will haunt you just like all the cars that Ford had to repaint years ago. We use plastic and olivene a gem from down south. When the body is all stripped to bare metal its all ready starting to oxidize, we go over the car with 80 or 100 DA paper, then we clean the car with metal prep (we use Glasurit paint products) we then give it one coat of self-etch primer followed by a good coat of epoxy primer. The next day we start our bodywork with a slight scuff of the epoxy, spray-poly, Hi-build 2K primer and so on, this is the only way we have been doing cars and this is the way most top shops will start. Good luck !

Thomas, I'm curious as to why the self-etch primer is neccessary? It seems like the scuff by 80 grit would provide suffient "tooth" to hold the epoxy primer. BTW thanks for the PPG paint code for Argent Silver (via my phone call) a few weeks ago. The Dupont store was able to cross-reference it to a Dupont code and it turned out nice.