Okay, so I'm late and catching up, but Richard J Kinch
wrote on Sat, 15 Apr 2006 01:16:51 -0500 in rec.crafts.metalworking :
pyotr filipivich writes:

Do not attempt to augment the cloud of smoke by firing a bag of flour.

Movie special effects use finely ground bentonite clay for this purpose.
Kitty litter in a ball mill. Properly inert while making a nice, opaque
cloud.

Aah. Now if I had known this some years ago, we might have used it for
"parade rounds".
As it was, we used "Gorilla round" - about triple the normal load.

--
pyotr filipivich.
as an explaination for the decline in the US's tech edge, James
Niccol wrote "It used to be that the USA was pretty good at
producing stuff teenaged boys could lose a finger or two playing with."