Hey I am currently working on a old 1976 mazda and was sanding back the underseal and there is a white undercoat is there a chance this is aspestos as I have read some old cars have it In the underseal
I think those who knew if '76 Mazdas had asbestos in the chip resistant coating have since forgotten. If I were you and that were an issue of concern, I would stop sanding and start scraping so that the material is not turned into airborne particles that can be inhaled. If the coating is hard, you might try warming it carefully with a heat gun to soften, then scraping it off in chunks. Normally when I remove material like that, I use a 3M Clean-n-Strip disc and it doesn't make dust but rather melts and tears off the flexible coating. If the coating dissolves with solvent, sometimes thats the safest, gentlest way to remove it but proper ventilation and precautions would be required.