"Letting parts sit on a heater that's in use anyhow works a treat." bought back a memory of last century when a place I worked at had an old bar heater used to warm bits up before application of high heat wrinkle paint,(great stuff to cover up after fabrication without a lot of finishing work), and we used to heat the bits, remove the rack and apply paint from an aerosol can. We did this in the store room.
One day apprentice decided to much hassle to move the rack so started spraying while the heater was on. Flames made him drop the can into the heater.
The fire was put out but he had a LOT of cleaning up to do.