What parts are safe to sandblast?

rickpaulos said:

That home brew paint should come off very easy. Even soap and hot water and a scotch brite pad will take it off.

Sand or shot blasting would destroy tins. Ice blasting would probably leave dents in that thin metal.

I bought a blaster and a box of walnut shell chips. Useless. I suspect my air home compressor wasn't powerful enough.

I've been using various non toxic orange type strippers with pretty good results. Very useful for small items. Not so great for full kitchen walls. There are some that you apply then wrap with plastic to keep the stripper from drying out. Others don't need the plastic. The claims of removing up to 7 layers of paint in 1 pass are bogus. A small tub will cost far less than any blasting service.

Kleen Strip with MTBE (the good stuff) is really hard to find anywhere anymore. Their less toxic version isn't so great.

Some Trek bikes are nearly impossible. I swear the finish is tougher than the aluminum frames. I've given up trying to strip those frames. Impervious to all chemicals. the rotostripper took chunks of metal out of the aluminum.

I used to use a ROTO-STRIPPER, as seen on TV. Fits in an electric drill so it only spins as fast as your drill goes. There are cheap knock offs that are prone to throwing wires so you have to very careful to hold it 90 degrees away from your head. Does a decent job on hard steel parts. Will go through tins. Won't get in to corners like most bike frames have. Will gouge mild steel. Will rip wood to shreds depending on the gauge of the wires.

Sanding. Not talking about old sheets of woodworking sand paper. Strips of emery cloth can take paint off pretty quick, including in tight corners. Not very good for flat surfaces. I recently bought a tiny hand held belt sander (1/2" wide belt) that's almost too aggressive.

Any time you have steel parts blasted, you need to prime them immediately, as in the same day. Don't touch the parts with your hands or greasy rags. I've had bike frames blasted and the blasters primed them minutes later. Primer isn't a sealer so you you need to paint your base coat the next day at the latest.

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BMX Punks! said:

Not to highjack this thread but does anyone know what would be the best way to remove old chrome and get a frame down to bare metal, 100% ready for cold blueing? The softer material blasting sounds like it might be right but not sure if that leaves a sort of rougher finish like sand blasting does?

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rickpaulos said:

What kind of frame? There weren't many fully chrome frames (except in bmx). Many old school road bikes had chrome stays about 1/2 way up. Some Spaceliners were full chrome (poorly done) but have so many nooks it would very hard to remove.

Chrome over steel directly vs triple plate?

Triple plate is 3 layers: copper : nickel : chromium . Typical on many old Schwinns. The copper is meant to fill in the pits to make smooth surface. Good triple plate involves polishing each layer. When it starts to rust, it forms tiny pin holes and the rust erupts and spreads over the surface. 99% of what is visible is just sitting on the surface. Will often clean up well. The best chrome product was Chrome Glo but they stopped shipping a couple years ago. The wd-40 & aluminum foil will scratch the surface and leave countless mini scratches. Steel wool will leave bits of steel wool behind that will rust very vast. Brass or copper wool won't do that. Car wax as a final layer will seal the pin holes so the rust won't return. I've tried to clear coat chrome but it never comes out well. I you can see the clear, you used way too much.

The cheaper method of chrome directly on steel was used on cheaper bikes like AMF, Murray, etc. Tends to rust and flake off. I've used emery cloth to take much of it off. Beware that the small flakes of chrome are razor blade sharp so wear heavy gloves and face protection. I have a large bench grinder with a wire brush wheel (and cloth buffer) that I have taken poor chrome off with. Works for parts, not whole frames. A good face mask is needed to keep the tiny bits of chrome out of your eyes. A roto-stripper would take chrome off but not in the corners.

A car battery charger, the right solution and anodes may work to remove the chrome electrically. But some processes will remove brass used in frame construction so it depends on how the frame was built. I went to a pro plating company to have a Schwinn frame chrome plated but they said their prep process would remove the brass. Well there are only minimal brazed joints (seat stay to seat tube & top tube to seat tube) on a electro forged schwinn frame but they still wouldn't do it.

I think chrome is harder than steel so any blasting that can remove the chrome will surely affect the steel. A big plus of blasting is it can get into the tight corners.

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