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Remove firescale in reducing atmosphere


#1

I have recently been experimenting with using my kiln and charcoal
while annealing sterling silver. I have a stainless steel pipe and I
fill it with charcoal powder to surround the silver blank during the
annealing process. It has been very time consuming waiting for the
pipe to absorb the energy and then release is so I could retrieve
the silver (approx 1 - 1.5 hour cycle). For grins, I decided to
experiment with a small ingot I intend to turn into a ring. I used a
propane / oxygen flame to anneal the silver between beatings, and it
turned it all shades from brown to black (the copper oxides). Once I
beat the piece flat enough to go through the rolling mill, I put it
in my make shift reducing chamber for the annealing process. After
removing it from the charcoal filled pipe, I noticed the
discoloration had gone. I was expecting this. My thinking is that
the charcoal is absorbing the oxygen out of the silver, reducing
cuprous and cupric back to copper. I have not run across this while
researching firescale, and wanted to get some feed back. My real
interest is in speeding up the annealing process when going from
ingot to ring blank. I’m wondering if I can disregard all firescale
concern and anneal with propane/oxygen and save the last annealing
for the makeshift reducing chamber. What are your thoughts?


#2

You might try argon gas in your annealing chamber will eliminate the
o2

Vernon Wilson