Enamel cracking sterling silver signet ring cool down
I am hoping that some will be able to help me work through an
enameling project I am working on.
A friend offered to walk me thru the enameling, and I did not read
up on the subject extensively as I should have.
As a result, I neglected to do many things that I have since read
that I should have done.
At this stage of the process, I am trying to research and
- why cracks in the enamel appeared after the 3rd firing (the cracks
followed the outline of the bezel like 1.5mm thick frame around the
(they would "heal, and then appear in another spot after each
- how the metal and enamel should be allowed to come down in temp/
It is basically a sterling silver signet ring, cast in Stuller
standard silver (silver/ copper)
the “base” under the enameled area is approx. 5.0mm thick (did not
hollow out. kind of (too) heavy. weighs about 28grams.)
It has a 1.0mm recess at the top of the ring, for an enamel
background around a raised element
I did not counter enamel under the head.
I depletion guilded it 8 times, (pickled in Rio Pickle, burnished
softly with steel brush and water after each firing, and neutralized
in baking soda) (I think I was supposed to glass brush between
I used Thompson unleaded opaque enamel #1685 cobalt blue, and
wet-packed/ fired it 4 times (I think I was supposed to glass brush
between firings. we touched the crack on the surface.), with a 5th
time for flash fire
I used diamond sanding pads to level surface before final flash
fire (400grit and 800 grit)
I have been researching, and picked up the following
- do not overfire past the 1400-1450.the solidus of the sterling is
(we fired at 1500 degrees F)
only use 1-2 layers over sterling silver, or the enamel will crack
(mine had 4 layers)
the recess should have only been about.30mm deep (mine was 1.0mm
the walls of the recess should be vertical and not rounded, where
bottom meets sides, and where sides meet top (mine was rounded)
I also learned that I neglected the below as well:
I did not glass brush between pickling when doing depletion
I did not fully dry the enamel before firings
I did not glass brush between firings
I am wondering:
if the above findings are all correct
and. after firing, what is the proper way to handle the piece, in
terms of how the metal and enamel are allowed to cool down.
(I have re-read my enameling books and I cannot really find anything
about cool down technique (for heavy items like a signet ring),
except stay away from drafts, and don’t place piece on a steel block
Any advice would be greatly appreciated!
I am planning to use diamond sanding pads (or my lapidary wet lap)
to grind down the height of the top down about.40mm, so that the new
depth of the recess would be approximately.40mm thick, and then
either flash fire to gloss it, or try using fine abrasives to get a
sort of shine finish. your thoughts?