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Crucible Life


#1

I have a small 2.25" whip type crucible that I have been using for
about to years. The borax lining started to recede, so I added more
borax and melted it in. I have tried to pour off any excess, but I am
getting red streaks of glasslike borax entrained in my ingots. I can
finish them out of the ingot, but I think that it is time to replace
the crucible (I have a couple extras). I have two questions: is it
possible to fix the problem with the current crucible? And, what is
the proper way to “season” a new crucible? The first one worked fine
for a long time, but I really don’t recall how I seasoned it. One
more example of the zeal of doing getting ahead of the learning.
Thanks for any help. Rob

Rob Meixner


#2

Hi Robert

One of my students posed this question on how long a Whip crucible’s
life span is. For me, once it gets so clogged with borax and metal
stuck on it, and generally unworkable, I save it for the refiners.
If you are that bounded and determine to reuse it, I ran this
experiment. I put mysilver Whip crucible in my ulrasonic cleaner for
a full week. Under the heat and vibration, the borax broke down and
released as much of the silver beads. However, after a few weeks of
drying out, I had my reservations about the crucible. When in doubt,
buy a new one. There’s a fine line in recycling in very scrap of
metal, to trying to extract scrap metal. As somne who does a lot
production work, at a $100 per hour, it’s not worth my time or
energy to extract only a gram o less of metal outof the crucible. I
will leave that up to your judgement. I ptrger to make mine known.

Joy


#3

I heat it up like I am casting flask with no investment and spine
with 4 twists to clean out clean

Don in idaho


#4

Rob,

I am still using one of Dad’s with no ill effect. I think it may
possibly be overcharged with Borax but it works well. As I melt I
continually stir the metal with a soldering pick. I pull a lot of
crud out of the silver and I know some of it is borax. I have never
used a carbon stir rod but I am buying one. And I was going to buy a
crucible and rack similar to yours as well. An experiment is in the
works I imagine.

Don


#5

Rob, crucibles are cheap! Treat yourself to some new ones. It’s just
not worth the time and effort to try to save one. You will be amazed
how much better your ingots and castings will come out when using a
fresh crucible after using that burnt up one you’ve been using for
so long. I replace mine regularly. As soon as I start seeing flakes
of zinc forming, it starts getting lumpy or the color starts
darkening, it’s done. Maybe twenty or twenty five melts?

I break in a new crucible by heating it to what seems like about
casting temperature and give it a dusting of casting flux (a 50 - 50
mixture of borax and boric acid in a salt shaker) and keep heating
it, applying another dusting or two so that it is evenly coated. You
want a thin but shiny coat, right up to the pouring trough (spout?),
but no more. If it pools at all, you’ve used way too much flux. Once
it’s fluxed, it’s ready to use immediately.

Another tip, use a separate crucible for each metal alloy. In other
words, have one exclusively for 14K yellow, another for 18K yellow,
and another for silver, etc. At a minimum, one for each color and for
each type of metal - one for yellow gold, one for white, one each for
rose and green and one for silver. Using one crucible for everything
can cause all sorts of grief. I keep an older one around too for
melting contaminated or garbage metals, like chains and sweeps, etc.

These tips apply to both dish style and centrifugal crucibles.

Dave Phelps