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Filler paste on casting?


#1

I have inherited someone’s commission. Many years ago, a friend
commissioned some belt mounts. The years passed and the mounts were
completed but not delivered until just recently.

My new problem children are large 2" square frames that will hold an
etched square in the middle. They aren’t really square but I can
deal with the geometry. Several of the castings have some kind of
filler paste slathered over them. Since I can see porosity on
several of them and a few with incomplete corners and a few with
little holes through them…it’s clear that the casting run was not a
complete success and it looks like this is some kind of patch job. I
showed the frames with the paste on them to someone who does non
jewelry metalwork and he says it looks like Bond-O, a car body filler
compound. It files off ok so I could get a smooth surface but what
would you do to hide the ugly gray paste? Can you plate Bond-O (if
that’s what it is)?

If it were my castings, I would have tossed them back in the “to be
re melted” pile but they aren’t.

So, my problem revolves around what to do to cover the holes or hide
the weird paste stuff. Is there an established methodology to "fix"
porosity or small holes? Is there a patching compound that can be
plated over?

Thank you for any help you can give me. The amount of useful
on this list is amazing!

Catherine Keegan
Albion Works
Albion, CA


#2

We have received "models " from some customers that have been
fixed/repaired touched up using Bondo or epoxy to fill pit holes in
their models from a previous caster. This may be what you
inherited… could be models that were never finished properly.

Daniel Grandi


#3

I think it posable that these items may have been original models
that were cast poorly and patched to be molded.

Larry Paul
Larry Paul Casting Co.
740 Sansom St.
Philadelphia PA 19106
215-928-1644 @Lpaul


#4
    I think it posable that these items may have been original
models that were cast poorly and patched to be molded. 

Nope. These were intended to be the final product. They’re in
bronze and have the bondo or whatever stuff patching holes.

Can you plate over bondo or other auto body fillers?

Catherine


#5

Hi Catherine; You didn’t mention what these cast frames were made of.
If it were my choice, and it were OK with the client, I would make a
mold of them using RTV (room temperature vulcanizing) mold compound
probably, and inject waxes and cast them all over. If I didn’t have
the equipment for that approach, I’d invest in a "Delft Sand Casting"
kit for about $75 and cast them that way, taking sand molds directly
from the originals. If the frames are sterling or brass, use a
chemical like “Attack” epoxy remover to disolve the “Bondo” away,
clean the metal thouroughly and if you are handy with a torch,
actually fuse weld using matching metal wire, or locate a local
welder with a “TIG” setup (tungstin inert gas) who can weld up the
holes. If you can determine what the metal is, let us know, someone
may have better suggestions. Good luck.

David L. Huffman


#6

Can you plate over bondo or other auto body fillers?

It’s possible to plate over anything if you want to spend a fortune
to do it. If the item was patched with bondo, I believe you may have
already seen a number of replies from other casters who suggest that
this was done to fill in a model that is to be molded and recast.
This is somewhat common.

Nobody fills a brass casting with bondo if it’s going to be plated ,
soldered or worked on in any way. Daniel


#7
You didn't mention what these cast frames were made of. 

They look like bronze. Not sure what she actually used for her grain.

If the frames are sterling or brass, use a  chemical like "Attack"
epoxy >remover to disolve the "Bondo" away, clean the metal
thouroughly and if you are handy with a torch, actually fuse weld
using matching metal wire, or locate a local welder with a "TIG"
setup (tungstin inert gas) who can weld up the holes. 

Thanks for the epoxy remover tip! I must admit that I’m both curious
to see what’s under there and a tad fearful of what the filler may
hide. My weenie torch isn’t up to fusing this stuff. But, I can use
the local art center’s torch set up. The clients haven’t told me
what they want to do with the castings now that they’ve seen them. I
hope they didn’t pay too much for them. I’d like to make another
master and recast the whole thing but I don’t think they would want
to pay for another go-round.

Off line, another jeweler told me that I might be able to use a
special paint to coat these poor things and plate over that.

I would like to thank everyone who has taken the time to help me with
this project. I can salvage some of these things but I’d really like
to be able figure out what she had planned to do to the ones with the
weird paste stuff on them.

Thanks again!

Catherine Keegan
Albion Works
Albion, CA