Framebuilders - Sandblasting ?

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fesslercw
04-07-06, 10:02 AM
Is sandblasting an no damageing method to remove paint from alum. and steel frames? If not, what are ssome other methods.
Thanks for your time.
ken cummings
04-07-06, 11:57 AM
Sand blasting is rarely done with common sand. Using hard abrasives like garnet or silicon carbide could eat into the frame metal or leave scratches. I would look up Dr Delron elsewhere on BF. He is a paint expert and should be able to tell you haw to safely remove a coating. Or contact the manufacturers' tech department.
Try some MEK or fingernail polish remover on some tiny hidden part of the frame. Forget blasting carbon fiber materials. I have seen ground walnut hulls used to "sand blast" sensitive materials. :rolleyes:
worthingtoncycl
04-07-06, 01:30 PM
It depends on the type of paint on the frame. Generally the frame can be bead blasted or even lightly sand blasted with no damage at all - However if the paint is powder coat and is bonded very well to the metal then you will need to do a chemical strip first to remove the paint, and then bead blast (prefered) or sand blast it before recoating. On Steel frames this is the standard method of pre-paint prep for new frames. Also you will want to make sure that the blaster is using clean sand or bead - esepically if they do cleaning of other products that could introduce grease or oils into the material as that will just coat your frame. Chemical stripping can be as simple as paint stripper from the hardware store, or in some cases depending on the frame material (alum vs steel) a caustic bath to remove the paint. Old solvent based paint will come of very easily with blasting.
I bought a sandblasting gun at sears that has a carbide barrel and I have used playsand and glass beads for blasting various types of automotive parts. I also use an auto paint supply water filter that attaches to the air inlet on a paint gun. I use the filter to absorb moisture in air line so that sand doesn't get moist and clog the gun. Playsand works great on steel but I wouldn't suggest using it on aluminum because it will wear away material and it does leave a rough finish, on the other hand, glass beads do not remove material and work great on aluminum and doesn't leave a really rough finish. I would suggest using paint stripper and use either a brush attached to drill or dremel, or bead blast those areas around joints to remove old paint. Its not really necessary to remove paint just to re-paint a frame. If the old paint is in good condition, frame isn't corroded, then sanding with progressively finer papers is all that is needed to prep the frame for repainting. Before you start any sanding, be sure to use an automotive 'wax' remover to remove any oils, silicones, or waxes so that new paint will stick well. You don't want to start sanding until frame or metal is cleaned so you don't simply sand contanimants into old paint or metal.
I bought a bucket of glass beads at Grainger supply and I blasted parts inside a cardboard box so I could recover most of the beads. Not sure if they sell smaller quantities other than the 50lb bucket. Be sure to wear longsleeve shirt, mask, and face shield if you ever consider blasting any parts.
fesslercw
04-10-06, 09:11 PM
thanks for all the help!!....questions answered!