Sandblast > Prime Advice

David Segura · Post by **David Segura** » Wed Jul 02, 2003 7:04 am

Let me start with what I do know. I have a 70 Ghia that I am going to do a pan off resto. I will be blasting the body, but not painting it. I plan on blasting the car in sections. There are two layers of paint on the car. The car will be painted (not sure yet) with a good paint, same color as original.

1. I do not want to damage the metal. Should I use Walnut to blast? Will it take it to the bare metal?

2. Planning on getting a Craftsman Air Compressor (6HP, 30 Gallon, 150 PSI, 8.6 SCFM 40psi, 6.4 SCFM 90psi) Is this enough? Overkill if I am blasting in sections?

3. What should I prime the car with after blasting to bare metal? Is there something else I need to do (heard about etch something)?

Basically I just need to get from blast to prime. Help would be appreciated!

Thanks!

JC-ATL · Post by **JC-ATL** » Wed Jul 02, 2003 7:32 am

Can I make a suggestion - don't blast it, sand it. Get a good DA sander and a pile of discs, and use those to take it to bare metal. You'll stand a lot less chance of pitting than with sand, and you'll make a lot less mess. Sandblasting makes an enormous freaking mess.

If you insist on sandblasting, get a bigger compressor. For that matter, no matter what, get a bigger compressor. Find the biggest compressor you can afford, and then get the next one bigger than that. You'll thank yourself later, I swear to this.

When you get the car to bare metal, prime it with etching primer, which actually digs into the metal a bit and bonds itself there. After that, a high-build sandable primer.

Good luck.

hillbilly · Post by **hillbilly** » Wed Jul 02, 2003 6:46 pm

mmmmm.sandblasting.......yep works good .The biggest thing with it is it gets every place and I mean every place.You will come across it or its results years from now.It will get down inside your doors all over your reglators and cause prmature waer blah blah blah. I have sand blasted hundreds of cars in my lifetime(not to mention logging trucks and farm equipment) and have used silaca.......causes lung problems..is fairly coarse and leaves a fairly pitted finish (primer sticks real good)

You must start at one end and evenly work your way back and forth or up and down.don't stop and start mid panel if aviodable or spend more time in a small area this will cause the metal to swell (warp) do not sand blast the inner of a panel if there are braces ect.,as this will warp the outside skin. Wear a good dust mask(note : silca sand is very dagerous to breath in and reuires a fresh air mask (as in painting) and full head gear). I have also used ordanary sand like on the beach just sift it through a window screen and presto. free sand.and it leaves the metal real smooth and primer still likes it.
When you get right down to it. Sand blasting is for rust....nothing works better. But if you have no rust (or very little) sand the paint off use a 80 grit disc. and follow up with 100 git when you get 90 % of the material off. Then use a small sand blaster for the remaining rust pits. You will do a much neater job and will appreciate the sanding process better than the sandblasting one trust me it's a crappy........ (can I say that ), job to do.

PitterPats73 · Post by **PitterPats73** » Wed Jul 02, 2003 9:42 pm

What about getting the car dipped? Meaning is this good or bad?

hillbilly · Post by **hillbilly** » Wed Jul 02, 2003 10:30 pm

That would be nice.seen it done looks real nice and all. I understand it cuts your body weight, mind you that can be good and bad.They used to have plastic bead stripping up here and it was the cats meow as it did not effect chrome or glass but took out little rust and no bondo,but you could see the numbers from felt pen or some type of marker from a 36 or so buick we done a few years back.No more due to inviromental issues. Dipping as I understand is large bucks .depends to as to how far you want to go....that would be a little more than a paint job

and you gotta dip the darn thing in primer to

any thing that is not good metal gets eaten away everything,gone,I am not to sure if you really do get the primer into all the little areas as the acid gets into as it is thicker so I would question that Ie:the drip rail where it is formed and folded for one? I don't know but am sure someone out there will let us know

JC-ATL · Post by **JC-ATL** » Thu Jul 03, 2003 5:36 am

Do yourself a favor - don't dip a Ghia. Eats the lead out of the fender gap, damn near impossible to fix properly.

Bobnotch · Post by **Bobnotch** » Thu Jul 03, 2003 6:04 am

Like others have mentioned here, sand it with a DA sander, then sand blast just the rusty spots, use a good primer (like an etching or epoxy) to seal any bare metal, as rust usually starts setting up on bare sand blasted metal in 15 minutes or less where I live (very humid). Also find the biggest air compressor you can afford, then buy the next biggest, as you'll need it. I currently have a 7.5 hp V4 cast iron series (Cambell Hausfeld) 80 gallon air compressor, and I should have bought the next size up. It works for what I want it to do, but it could have been bigger. I hope this helps.

JC-ATL · Post by **JC-ATL** » Thu Jul 03, 2003 6:54 am

Bobnotch wrote:I currently have a 7.5 hp V4 cast iron series (Cambell Hausfeld) 80 gallon air compressor, and I should have bought the next size up.

D a m n, Bob, that's a mighty big compressor for a home shop, and you say it's not big enough? What in hell are you trying to do with that thing?