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Ferric chloride & firescale


#1

Hello All: my question is can ferric chloride be used to remove
firescale in the same manner that one would use nitric acid? Thanks,
Marc


#2
can ferric chloride be used to remove firescale in the same manner
that one would use nitric acid? 

If I might back up on this question for a moment… using nitric for
removing firescale? On sterling? Please tell me more. I’ve always
got an ear open to learn, but this make me say, “Hmmm?”

I’d be concerned about the removal of silver. I’d instinctively be
more inclined to use ferric chloride (to remove copper but not
silver). Ferric nitrate or nitric acid would be a mordant both the
silver and the copper. Is that desirable?

What impact on the finish of the metal, which I would probably have
at a polished or pre-polished state? What influence does ferric
nitrate have on the finish of a finished piece of sterling?

I try to avoid firescale (an ounce of prevention…) but on occasion
have to deal with it.

Inquiring minds…

Dave

Dave Sebaste
Sebaste Studio and
Carolina Artisans’ Gallery
Charlotte, NC (USA)
dave@sebaste.com


#3

Dave, I use nitric to remove fire scale now and then. You are
correct that the best way to remove fire scale is not to get fire
scale, but sometimes it does occur and usually in areas where you
cannot get at it!

I use a mixture of 50/50 - nitric/water. I use it cold though I
have heard some people warm it for faster action. This has to be
done under carefully controlled conditions, like a very open well
ventilated room or outside, the container for the acid must be of the
right type and the area around it clear of any metal…also
protected, etc, etc.

I warm the item to be cleaned and drop it directly into the
solution. It will immediately begin to produce bubbles. Wait about
20 secs, remove it with plastic tongs and drop it into container with
baking soda/water solution to neutralize the acid.

This results in burning of the firescale and leaves a white silver
surface. Now and then it must be done more than once. Be careful not
to leave it in too long. Only do this before your final
tumbling/polishing.

Cheers from Don at The Charles Belle Studio in SOFL where simple
elegance IS fine jewelry! @coralnut1