The Stovebolt Site Forums The Shop Area Paint and Body Shop Surface After Sandblasting

Just got my frame sandblasted. I was surprised at how rough the texture is now. Is the primer/paint going to smooth it out? Would powder coating be better?

Thanks

They used what's called large particle sandblasting, Kevin. Larger particles give you harder impact and deeper penetration. Smaller particles give less impact and less penetration (and a smoother surface). At this point I doubt there is much to do but prime it. Epoxy primer is good but can be costly. Plain old lacquer primer is a whole lot less expensive but some people today have decided it isn't what they want. You can cut it 1.25 to 1 (thinner to primer) and it will go on nicely. Even 1:1 is okay if you're living where it is a little cooler. A product like this: Evercoat 102260 – Dura Build 2.1 Gray Gal is about $100 a gallon plus your thinner (get a slow dry thinner this time of year).

10-4 thanks

The rough surface will result in a non-smooth/non-glassy final finish. If you prime it with a thin primer-sealer, it won't hide the roughness, if you want a smooth finish, you will need to prime with a primer-surfacer that is intended to be sanded, then more primer until you have the desired smooth surface on which the topcoat will sprayed. My opinion on powder coat is that the plastic envelope that is created will hold water under it and rot out the steel. Just my 2 cents.

Primer/surfacer on a frame will be "interesting"- - - - -trying to sand on a frame rail is going to be quite an adventure, at best. I'd suggest using some kind of undercoater that will build up a thick enough layer to sort of hide the roughness. How many people are going to do a detailed inspection of the frame once the truck is assembled, anyway?
Jerry

Jerry you are exactly right the frame is not something that is looked at very closely. I'm not doing any sanding. If I wanted to do that I never would have had it sandblasted.

I just didn't expect the surface to be that rough. But the guy who's going to paint it uses this sandblaster a lot so it may be a non-issue. He hasn't seen it yet. I am just a novice doing this for the first time.

That is my standard process/best practice whenever I can. I blast with 60 grit blast material, then coat with an epoxy primer. Even my epoxy ends up with a little shine to it.

With any process, the shinier you want the finish, the more polishing (sanding) you have to do. Steel pieces get cleaned, sanded, polished, coated, polished, coated, polished, then final coated with chromium.

Painted surfaces are cleaned, worked, cleaned, filled, cleaned, epoxied (or these days, epoxied, then filled), sanded, cleaned, primed or surfaced, sanded, cleaned, repeat, repeat, sealed, sanded, color coated, sanded, clear coated, etc. The more layers, the more sanding, the smoother and shinier the final product.

Picture attached of my Model A blasted, then epoxy primed. More work to be done after all the metal working, fabrication, fitting, etc. Important thing is all the rust has been arrested and the metal is sealed so the rust process can't start again. Not something that necessarily happens with a non-epoxy primer.

I agree with the notion that sanding the frame after primer-surfacer would take more gumption than I have, I was trying to describe the effect. If it were my project, I would shoot a good brand non-sanding epoxy primer and a top coat of satin frame paint.

Thanks for all the feedback.

I'm glad to say that after some sanding at the shop where it is and one coat of epoxy primer, it is looking good. I think he is going to sand again and apply another coat. I think it is going to look pretty good.

Two coats of epoxy prime flows very nicely to cover imperfections, especially sandblasting texture. The second coat goes on as soon as the first coat flashes. That is the key for filling in this kind of surface imperfection. The second coat softens up the first coat resulting in extra flowing into the sand pits.
If you wait a day for the second coat, it doesn't work.