Uh... Do you know what you're talking about? Combustion means fire, burning, you're not burning anything, first off. When you do oil on TI, Quartz, or glass, you're getting it hot, then dab, it's called flash vaporization, NOT combustion. There is no combustion, and if you bring it too close you'll just heat it up too hot and it will probably just boil off, do you combust water when you heat it? No it vaporizes. You should use your torch away from the stone, and it will heat up and flash vape. The only argument you have is if the oil has plant matter in it, which is probably the case with the one dude who had "ash." Sometimes when I dab I get some particles, but it depends what I make it out of. There is a clear difference between combustion and vaping, if it was combust, you would know.