I recently purchased some flash paper from a local shop. Works fine, except the burn speed is relatively slow. (A piece approximately the size of a playing card takes almost a full second to consume. More if folded.)

Is there anything I can do to speed up the process? Or did I just get a "bad batch", if such a thing exists?

The paper itself feels a touch damp... perhaps that's it?

It's most likely because it's damp. You need to let it completely dry out before you use. They ship it damp for safey reasons. Just let it dry over night and it should burn much faster.

Postal regulations require flash paper to be damp in order to render it 'safe' for shipping.

Regan

I left them out overnight and that has solved the problem -- thanks!

This may be a weird question, but given that the flash paper still burns (albiet more slowly), what is the point of shipping it damp, exactly?

I believe it's less likely to ignite in the heat or with a spark when it's damp. You have to hold it to a lighter to make it combust. So unless it caught on fire it would a lot safer.