[Anitius Severinus Boethius]

What was he spraying that caused an explosion like that?

[Tolerance Sucks Rocks]

Could be anything. Aerosol sprays can be propelled by volatile hydrocarbons, among other things.

[ErnBatavia]

I used to have an apartment with high wood beamed ceilings....when I'd see a spider way up, I'd take a can of Right Guard, flick my bic and blowtorch him.

I did this tons of times and never had a problem; works great.

[Secret Agent Man]

Aerosol cans’ propellants are often flammable and have warnings not to use around flames or to delberately heat up the can.

[Joe 6-pack]

You'd be amazed at how explosive even relatively inert substances can be when aerosolized in a confined space. It's the same principle behind grain-silo explosions.

It could have been anything as tame as hairspray....

[6ppc]

What was he spraying that caused an explosion like that?

Probably hairspray. Ever fired a potato cannon?

[Lando Lincoln]

Could have simply been hairspray. Very expolsive.

[njslim]

Many aersol contents are flammable - ie hair spray

also since Freon was banned many use hydrocarbons like butane are propellents

[editor-surveyor]

“What was he spraying that caused an explosion like that?”

.
Many aerosol cans now use propane or butane as a propellant, since freon has been outlawed.