You could steam de-wax, I use this all the time. It removes all
the wax before you put the flasks in the kiln and you don.t get
all that smoke & smell of burning wax.
I using an old blue canning kettle, the enamel ones, you can
pick them up pretty cheap at garage sales or flea markets. Do
not use a good saucepan, some waxes have plastic in them and it
is almost impossible to get the wax off the pan after. Put a rack
in the bottom of the pot to keep the flasks up out of the water,
put in water to below the rack & place your flasks on the rack,
sprue side down, put the lid on & put the thing on to high heat.
The steam will remove the wax, takes about an hour, however
check them once in a while you can see when all the wax is out.
When your flasks look nice & clean & free of wax place them in
the kiln at 500%F & carry on from there on the standard timing
for the size of your flasks. Ireally like this method, it gives
you a nice clean burnout & cuts the kiln time down, also keeps
your kiln clean. I do the dewaxing on the gas burner of my
barbeque, saves the kitchen all steamed up.