When figuring out how much rubber to use, stack them next to the
frame. The amount of rubber you use is that amount plus one. You cut
the extra sheet in half and put it on each side. If your piece is
shifting on the inside, you don’t have enough rubber pressing it into
place. If the mold is not working from the same PLACE in your
vulcanizer plates, you may have a bad heating element. I do two at a
time also with no problem. Make sure you count the same amount of
sheets for both sides.
Here’s a little tip. On the outside pieces, leave the cloth side on
the rubber. This fiberglass / cloth backing will shield the plates
from the sulfer content of the rubber. This sulfer stain is hard to
get off. If you use the vulcanizer for anything else you want to keep
your heating plates like new.
One other thing is that when setting the item up your spru rod should
go through the spru former into a hole in the frame. This will keep
the object centered while vulcanizing. It will also give you your
cutting path to your model.
Your model doesn’t matter it’s only the thickness of the mold that
The time vulcanizing is on a ratio of one inch of mold frame per hour
with a 40 minute minimum. Dont’t vary that instruction. Don’t vary the
temperature either (307 degrees F if you can do it). I believe
Castaldo documents this well.
The holes in the frame are a good success guide. You should have
rubber worms pushing out of the holes after 10 minutes. If you don’t,
you don’t have enough rubber. You can stop and with some hot gloves
on, add a half piece to each side and go back to pressing. Look for
the worms of rubber pushing out. Both sides of the frame should match.
If you have worm or vent holes on one side make them on the other
TR the Teacher & Student