Am I the only one getting PITS in my sterling silver castings? I have
tried several different companies. I am more experienced with gold
so I was not sure to believe the caster that told me it was a common
thing in silver.
Any suggestions? Jacqueline Sanchez
One thing that can cause pits is an inadequate flux cover when
melting or using an oxidizing flame to melt. Molten silver can take up
about 22 times it’s volume in oxygen which doesn’t stay dissolved
when it solidifies. Result gas bubble porosity and surface pits.
Jesse
Nope you are not the only one who gets pits in your silver. Last
Thursday I vacumme cast multiple peiced and it seems that at least 5
of them have pits. I’m not to sure what this is from. Could it be
from having air bubbles in my investment, or not letting my wax burn
out long enough… Any suggestions on how to fix this problem?
Dear Jacqueline, I cast between 25 and 50 ounces of sterling a week. I
can’t claim 100%, but close to it for pit and firescale free
castings. There are too many variables to list here. If you would
like to call and talk, my office hours this Spring are Tuesdays &
Thursdays from 8:00 to 10:00 am Central Standard Time.
Best Regards,
Todd Hawkinson,
TR the Teacher
Hello Jacqueline:
You need to find a caster who will work with you and help you trouble
shoot. Until recently I found most of the casters I worked with very
eratic. Sometime a piece would turn out perfect, other times the same
piece looked like it was dragged behind a car for a couple of miles.
I am now using Daniel at Racecar jewelry. He is an orchid member. He
takes the time to examine my pieces and help me trouble shoot. This
is the first time I ever had a caster try and educate me. I have
been through every caster in NYC and found most of their technical
advice has been less then great. Most times I felt like I was getting
excuses instead of results. I originally come from a different
industry, graphic design, where professionalism and courtesy towards
a client is a standard. If a client is pointed in the wrong
direction, educate them and work with them. It is just good business.
Dan does this. … Anyway, check out Dan’s website,
www.racecarjewelry.com… So far I am very happy. I have learned so
much since working with him. Its great!
dede
Hi Jaqueline, We cast every day in all fresh sterling silver and get
great results. Please feel free to e-mail me off-line for more
details. We have been casting for art jewelers for fifteen years.John
A. Henkel J.A.Henkel Co.,Inc., Moldmaking, Casting,Finishing
Silver is much more “fluid” in the molten state and doesn’t need as
high a flask temp when casting as gold. It also will stay in a
molten state longer than gold. For these reasons make sure that the
flask temperature is adjusted and that you aren’t using the same
flask temp that you would for gold. Another thing to check is the
thickness of the waxes and the sprue transition. You want to make
sure you have even thicknesses and especially that the sprue is not
too small for the casting. Silver, due to it’s low viscosity will
fill a casting even if the sprue is too small. Thinner areas of the
casting solidify first and as they do they shrink. The sprue
contains the reserve metal for the rest of the piece as it solidifies
(and therefore shrinks) If the sprue solidifies before the rest of
the piece there will be no molten metal in reserve for the piece to
draw from. It is this “shrinkage porosity” that is most common and
probably what you are experiencing. When you get the proper flask
and casting temps down and your sprue has been modified your porosity
will probably go away. Even so some major casting houses still have
not got it right yet. Don’t give up. Silver is a real joy to
cast…I used to love casting it because I could do several hundred
pennyweight at a time, unlike gold where I rarely got to sink my
teeth into such large castings.
Larry Seiger
JA Certified Master Bench Jeweler
Hi Amanda, Mostly , pits are caused by having the metal too hot when
you cast. Tom Arnold
there is a book “JEWELRY MFG THE ART AND SCIENCE” it explains silver
casting. contact The CONTENTI CO. for a copy 1-800-343-3364 ask for Arthur