Shake

The very issue that a comparison between BP and Flash is being made demonstrates the need for significant research. They are SO different! It is great that you have asked the question, but PLEASE proceed with caution.
My first experience with flash was terrifying (and a little exciting), I really didn't believe what I read about how powerful it can be!

The fact that you need to hide your hobby from the Mrs. is also concerning from a safety point of view. It is hardly fair to be practicing pyro near people who are not aware of the hazards. Many of the chems used present serious health hazards in addition to the obvious hazards when combined.

Good Luck but please be careful and read, read, read!

I have always had concerns with coffee grinders.
Before I had a ball mill I used 3 coffee grinders to mill powders. One was for oxidizers only and one for fuels only, the third for black powder.
My concern arose when I had to dismantle my BP only coffee grinder due to operational issues and, to my surprize, the motor and coil inside was coated with wonderfully fine BP; that immediately screamed.."Explosion Hazard!!!"
I quickly stopped using coffee grinders and made a ball mill.
I feel much safer!

For larger shells to save on weight and chems you will want to use meal coated rice hulls or whatever (I use vermiculite)

Hey Bonny;

Out of curiousity, what method do you use to coat the vermiculite? And are you happy with the results. I've read and am in the progress of using rice krispies and am anxious to try them.

Chris

If that's the case wouldn't a simple varnish/wood sealant work?

Not trying to be difficult here but just looking at the simpliest method available.

what is the advantage of treating cardboard mortars aside from durablility?
Does this increase performance or safety factors?
Just curious.