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Jewelers "Bondo"

Is there a product that will serve as a filler material on models,
that can withstand the heat of a vulcanizer? Sometimes we might have
an incomplete solder joint, or a pit or something of that nature in an
area that is too difficult or risky to solder fill. I would like a
product like a thin “bondo” or an epoxy or something like that,
viscous enough to be applied with a syringe, and can stand the 307
degree F. vulcanizer for multiple molds.
Is this product a dream or is there something like this out there?

“JB Weld” an epoxy that is available in tubes at hardware stores.
Will stand up to powder coating (400 + F) so it could easily be

Mark Chapman
White Wolf Jewelry Arts

I have used epoxy or crazy glue for this purpose. Keep in mind, the
glue will withstand one vulcanization. If for any reason you need to
take another mold off the master model you will need to clean off the
old glue and reapply it. The glue tends to adhere to the mold, but
can be picked off.

I hope this helps.
Kate Wolf

Possibly “J. B. Weld”, which is a 2-part epoxy product that can and
has been used to repair engine blocks. I’m not sure if it’s thin
enough in it’s unset state to flow in a syringe, though… You can
find it in almost any auto-part, hardware, or big discount store.

 Ron Charlotte -- Gainesville, FL
 @Ron_Charlotte1 OR

Hi J.D. Hope I am addressing you correctly as J.D. You might try
"furnace patch" or maybe one of those “liquid solder” type materials
that are sold in many hardware departments. Otherwise, why not fill
with lead/tin solder? Use small clips of solder. Most of those melt
at over the 350 degrees or so that the rubber cures at. . .but here’s
an old model maker’s trick. If you’ve got a wax pen, you can turn it
up all the way and actually burn into the rubber molds. If you don’t
have a wax pen, get an inexpensive “wood burner”. Perhaps a soldering
iron might work, but I’ve not tried that. This trick only works well
with the standard packed rubber molds. The silicone type compounds
won’t burn, and the RTV types don’t burn well either. You see, every
concave pit, crack or other on the model will have a positive
counterpart in the mold which you can burn off. You can also use this
method to add extra sprue channels or enlarge a too-small sprue. If
you are using the silicone or RTV type rubbers, you can use a very
sharp scalpel and slice off the protrusions which are causing pits in
your waxes. Hope this helps.

David L. Huffman

Aloha JD, Superglue, milliput, or my favorite epoxy ( 2 part ribbon as
opposed to 2 part liquid) will work. It also depends on the rubber
also, Castaldo Gold label will never let you down (Thanks, Michael ).
The ribbon epoxy can be thinned if needed, if you want specifics,
call me or drop me a line.

Best Regards,

Christian Grunewald
Precision Modelmaking Technologies
(808) 622-9005
Technical Representative For