Digital BW, The Print

I bought a few cans of this to try on matte prints.

Oddly, there's no instructions on the can (just not to breath the stuff 
or set it
on fire).  I also Googled looking for some instructions, and found nothing
specific (just to use it outdoors and that it's seems popular with 
pastel artists).

So how should I apply this?  Multiple coats?  How long should it take to
dry? Any gotchas to worry about?

If I missed the key URL that has all this info, I apologize in advance.

Thanks!

Scott