Are you protecting yourself when you grind, buff, and everything in between? Not only should you be using a heavy-duty ventilating system, you should also wear a 3M Easy-Air high efficiency respirator. The respirator below is a 3M 7502 (medium size) half-face respirator (about $23), with 2047 pancake filters (about $6 per pair). The entire unit weighs only 4.5 ounces, so it can be worn all day (and night!). The filters will protect against welding fumes, dusts, mists, and asbestos. There is also an encased charcoal filter that will protect against nuisance smells. This respirator is most effective if you are clean shaven. Regardless of how powerful your ventilation system is, when buffing the inside of a form dust will become trapped and circulate out and away from the mouth of the vent, hence the need for the respirator. Don't bother with nuisance or dust masks, they simply aren't as efficient.
Always mark your respirator with the date the cartridges were installed. Also, clean the respirator often, especially after a cold or other sickness.
If you need help with finishing, call SAS for experienced advice. For respirator selection, contact 3M Occupational Health & Environmental Safety Division, 3M Center Bldg., 275-6W-01, PO Box 3325, St. Paul, MN 55133, 800/243-4630. Purchase from safety supply companies.