Setting the scene: smell and taste

[Chris]

I'm running along at full descriptive tilt and come to the realization that I have no idea how to describe spent explosives. I improvised it as a sharp burnt odor hanging in the air and they fell for it!

Still, what do spent explosives smell like; C4, Semtec, dynamite. Do they have a distinct odor when you pull them from the wrapper for that matter? Is it so strong you'll taste it as well?

Thanks,
chris