Dear Jack, I would like to respond to one section of your last
message. In regards to your question of RTV vs. Vulcanized molds,
these two compounds although similar in purpose, serve differently.
RTV molds are obviously room temperature vulcanized molds, which gives
you the ability to create a wax master and produce a mold without the
risk of melting the master. Now as I am a firm believer that you can
yield better detail from a RTV mold, these are not production molds.
RTV does not have the tinsel strength of a vulcanized mold. I would
recommend creating your original piece, if you do not already have it,
from wax. Make an RTV mold, and shoot some injections. You will cast
those until you have a good piece that you can make your new master.
You will take that master and create a vulcanized mold that will serve
as your production mold. You must account for shrinkage along the
way, which can vary based on wax type and mold type. All of this
unfortunately is not as easy as it sounds if you have not packed and
cut molds before. Rio Grande carry’s some very good videos on mold
making that I feel would be very useful for you. Always keep in mind
the cast ability of your patterns when originally spruing your master,
and take into consideration its ability to drain during burnout. Since
I am not aware of your current casting method, I can not intelligently
make any suggestions to that at this time, however, be aware that
different casting methods require different spruing and treeing
techniques. One last recommendation, would be to get yourself a clear
RTV compound to start out. This will give you the ability to cut a
few molds while viewing the master internally.