Instead of gloopy coolants

Hi All; Some of you have mentioned using “cool-jewel” (sp?) and other
gelatinous products, as well as wet cotton, etc., to prevent a stone
from exposure to excessive heat when soldering. I would like to
suggest a product I was introduced to many years (decades, really)
ago that I think is much easier to use and more effective. It’s
called “Feldina” and the only supplier I’ve seen who carries it is
Geisswien (sp?). It’s a gray powder, looks like asbestos but it
isn’t. Add water to achieve the consistency you want. It’s easy to
submerge an article in, holds water well, and cleans up easily and
it’s fairly cheap.

David L. Huffman
David L. Huffman Studios, Inc.

Hi I use a simple mix of olivine grits and an old soup can… the can
is mostly filled with cement and 1\3rd casting sand… i float water
on top…and enclose the stone in the resulting mud… then i make
sure the water is barely above the sand and proceed to solder…
with a hot flame i have been able to solder large silver mens rings
with out removing the stone. As with everything there is a learning
curve… ya can’t mess around and even if the water evaporated the
mud still throws off the heat… It has worked for me
for 25+ years… ringman

..."Feldina" and the only supplier I've seen who carries it is
Geisswien (sp?). It's a gray powder, looks like asbestos but it

Does it act at all like clay? The name suggests it might be
feldspar. People also use saturated sand, or any other
heat-resistant material. As long as the water can’t just drain off,
almost anything should work, no? Noel

To reduce a stones exposure to excessive heat when soldering try
this. Get a pet food can or tuna fish can and a lid plastic which
will tightly fit it . Fill the lid nearly to the top with clean fine
sand. Wash the sand if needed. Add enough water to make it very wet
yet moldable. Then squish the sand into a M shape and place the ring
sticking out of it Deeply bury the gemstone and leave only the shank
or offending portion exposed. When You add boric acid, paint on and
burn off the alcohol several times. Use enough to make a pasty
covering on the sand it is cheap. This protects the stone from heat
and the ring from oxidation . When You solder , place the solder on
the top and heat from below up . A smith little torch with a # 6 or
7 tip will produce a large QUICK heat . Place the lid on the can until
it is next needed.


1 Like
    Does it act at all like clay? The name suggests it might be

Hi Noel;

Not exactly. I have no idea what Feldina is made of, but I’d be
pretty sure it’s not clay. It’s a powder when you get it, and the
consistency you get varies depending on the amount of water you add.
You can make it very soupy or quite stiff, but it’s hard to describe
the consistency itself. It’s very silky and light, yet firm enough
to hold an article up if you don’t make it too thin. You can pack it
down behind a stone, and stand a ring up in it. I’ve tried them all,
wet sand, wet tissue, cool-jewel, just water, potatoes. I would much
rather use the Feldina.


My favorite is a product called Thermagaurd, made by Vigor, it is a
ceramic wool like stuff. You tear off a bit of fluff the size you
need, soak it in water, and you can stuff it behind a stone, wrap it
around an area, wrap the tweezers with it, or whatever. It will wick
water up from a tray, if the job calls for that. It is reusable,
clean, there are no fumes. It is supposed to resist temperatures up
to 2000 degrees, because it forms air pockets wich reduces heat
transference, as well as holding water. It is far superior to any of
the jell products that dry out, crack, and fall off if the job is
big. Marggi

Hello All: A few years ago, I put together a web page explaining how
to protect heat sensitive components while soldering or even welding
other parts of the same item by holding part under water with the
use of a third arm tweezers. The link is below.
Yahoo | Mail, Weather, Search, Politics, News, Finance, Sports & Videos I have been
successfully using this technique almost daily for many years now
without a problem. I learned it from a Master who learned it from
someone else. Michael R. Mathews Sr. Victoria,Texas USA JACMBJ