The white stuff is either phosphors or paint, I can't recall which. Phosphors are REALLY bad, paint isn't as bad but you still wouldn't want to breathe fumes from burning paint. I just use a clear bulb to begin with. Also, vaporizers aren't great with most weed, but if you have the trichrome dust that collects at the bottom of the bag put that in your vape and use a rubber tube between the vape and a bubbler to cool and clean the smoke. Do it in one or two hits, you'll be fucked up as hell.