There is another issue with heat guns. I don't know from experience whether this could start a fire, but it might. If your heat gun gets dust into it, either while running or before running, the heating element can transform the dust to sparks which are ejected from the gun along with the hot air. It seems quite possible to me that glowing fragments from the gun could start a fire by landing in sawdust.

Bottom line is that clean is better, and pay attention to anything visible that comes out of the gun.

Good luck,

Allan Edie

: You need a lot of fine dust to meet the lower explosive limit. I
: wouldn't worry about using a heat gun.

: From http://www.wclib.org/pdfs/msds6_95.pdf

: FIRE & EXPLOSION DATA
: Flash Point...........................Not Applicable
: Autoignition Temperature.................Variable
: (typically 400-500°F)
: Explosive Limits in Air.....40 grams/m
: 3
: (LEL)
: Extinguishing Media...........Water, CO2
: , Sand
: Special Fire Fighting
: Procedures...................Wet down with water
: Wet down wood dust to reduce likelihood of
: ignition or dispersion of dust into the air.
: Remove burned or wet dust to open area
: after fire is extinguished.
: Unusual Fire &
: Explosion Hazard.................Strong to severe
: explosion hazard
: (if wood dust "cloud" contacts
: an ignition source)