Sorry that it has taken this long to respond to the question of
sprue size for steam casting. The other sources are correct. I
have tested 10, 12, 14, 16, and 20 guage sprues to test which
gave the best results. 10 and 12 were just too large and the
silver did enter the wires and freeze. 14 and 16 gauge worked
good most of the time, but if the flask was accidently jarred or
moved in anyway during the melting process resulted in no cast.
18 guage seemed to work fine, but is hard to work with,
frustrating, but I think worked the best. 18 guage worked better
with pewter. 20 guage was just too small to work with and did
not let the metal cast fast enough.
Thankyou, for reminding me that I did not cover this most
important part of “Steam Casting” in the detail that I should
have. I got caught up in my own deadlines to finish that section.
I will add more info about other ways to sprue for Steam Casting
at the beginning of “Burn Out”. I hope to finish it soon, some
time this week.
I should have explained how I usually use 16 or 18 guage wax
wire. I take two lengths about 1 inch long. I fold them in half,
making four wires and twist them together at the fold. This makes
what I call a “quad pod” with the four 18 guage wires being
attached to the sprue base after I cut them off to about 1/4
inch. After I cut off the twisted end at about 1/8 inch it is
about the size of an 8 guage sprue wire. This is attached to the
wax pattern. Remember, I am trying to teach this for people who
have no experience, equipment or supplies.
I also forgot to discuss figuring out how much metal to use. I
will cover this also this week. Then we will add this information
to the proper installments of the Steam Casting Class.
The next installment Steam Casting #5 - Burn Out is almost
finished and will be posted sometime this week.
Thanks again for your questions and imput. If I have not covered
anything or you have some better way to do any thing concerning
Steam Casting please let me know.
I just read the article in October, 1998 issue of Rock & Gem
written by Mel Williams. It is the best article that I have read
on Steam Casting. I do not disagree much of what he has in the
article. I will point out a few differences about my experiences,
especially with the equipment such as the caster and the kiln. I
hope to talk with Mr. Williams via phone this week.