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Slate dishes for borax grinding

Just wondering- is there any reason one can’t use an unglazed ceramic
dish for grinding the borax cone, instead of slate, if it’s so hard
for some to find? I can’t help thinking one might get slate dust in
the dissolved borax. I’ve been using powdered borax mixed with water
for some time now. When it dries up in the little dish (like
overnight), I just add a few drops of water, and smash it up again
with the handle of my soldering tweezers. Takes only a second. (I
guess I could go all the way upstairs, get a spoon, and use the
handle!) I also tend to cut more solder chips than I need each time,
and leave each grade in its own labelled jar lid with a covering of
borax slurry. When it dries the chips are sealed in, presumably not
developing tarnish. Then when I need a particular grade I just add
drops of water and smash it up. Presto- clean, pre-fluxed solder. I
don’t know if this is a good idea or not- it just evolved. Input? I
do cover the lids to keep dust out, and wash them out if the borax
looks less than white. I know some people put the borax solution into
a spray bottle, but for me it clogs immediately. Where are all of you
getting these borax cones? I feel like trying them now. I don’t
remember seeing them pictured in catalogs.

This brings me to a question…I use the alcohol/saturated boric acid
solution trick to prevent firescale: dipping, burning off, then
fluxing. I’m happy with the results, but can’t get it to work well
with an anti-flux such as yellow ochre. If I apply the ochre first,
of course it washes off in the alcohol solution. If I apply it after,
the ochre bubbles off the film when heated, turning into mud,
usually running straight to the join I want to solder. Is there
something I’m missing? I’m not crazy about using white-out - can’t
get the applicator brush or tip to deposit a fine enough line. It
sometimes leaves a grey stain I have trouble removing, too.

Lin in suburban Chicago

In Europe the standard dish for grinding borax IS a hard fired
porcelain dish and NOT a slate dish.

Tony Konrath
Gold and Stone

Hi Lin -

The only catalog where I found the borax cones was Frei and Borel.
They no longer carry the borax slate. The borax cone is not shown on
the website - however, it is in their paper catalog - part #154.252.

Frei and Borel is in Oakand,CA 800-772-3456 or on the web at: Their email address from the website
is :

In response to your yellow ochre question - your trial and error has
already answered it! Since the yellow ochre is a solder inhibitor -
it is necessary to avoid contact with the flux for the very reason you
described. Also, I apply the boric acid/alcohol solution with a brush
and this way, can avoid touching any area where yellow ochre is
applied - to prevent the contamination to the soldering area. Some
sections of the metal may be missed with the firescale preventative -
but more importantly, the solder will flow. If you were dipping the
yellow ochre in your boric acid/alcohol solution - it may be
contaminated now. Perhaps, that mixture could be used still at times
when you are annealing and not soldering - so it is not wasted (just
an idea). Also, it is important to remove (wash off) the yellow ochre
on the piece after soldering - before putting in the pickle solution -
because of the iron content.

Hope it helps. Couldn’f find the string in the archives for you
about keeping the sprayer unclogged - but in the past, there were some
good suggestions. Cynthia

You can get small “mashers and smashers” mortars and pestles from
: American Science & Surplus

a 130 Ml 4 inch dia by 1/34 in is part # 88314 at $5.75

They have bigger ones.