Cleaning a Casting

Jewelry Discussion
1

I have read all of my textbooks and have also done a lot of research
on the Internet and the Orchid archives and I still have a question
about what is involved in cleaning a casting. Once a casting has been
received back from a commercial casting house, what is involved in
cleaning it? Thanks in advance for your response and apologize if
this question sounds elementary. I would greatly appreciate advice
about how to hand-clean the casting, i.e. with sandpaper or other
materials as I would rather do that than buy yet another machine.

2 
what is involved in cleaning it?

Any method that works for you.

If the casting house has the equipment you can request they tumble
it. This gets into all the nooks and crannies. Less work for you.

Rubber wheels on a flex shaft. I prefer those soft blue wheels. Form
fitting.

If you mean entirely by hand, yeah sandpaper would do it… If you
need to true up flat surfaces use a file. This leaves cutting lines
which can be reduced by using a fine file in a circular motion after
you’ve planed it off. Then polish as needed.

Unless you mean your castings are coming back with investment still
stuck on. It can be picked off. If there’s a lot of it you should
talk to your caster about why its there.

My own pet peeve (well, one of many) is when the caster uses a coarse
large abrasive wheel and just goes hog wild. pointless. arghhh

3

Annabel,

This is a subject that I am sure will bring many responses since an
entire book could be written on the subject.

First off, for the sake of clarity let me say that cleaning a
casting and finishing a casting could be viewed as two separate
ideas.

Cleaning a casting involves removing the investment that was used in
the casting process and since this subject has been dealt with in
depth lately on Orchid I will assume you would like to know how to
finish a casting.

First the raw casting needs to be pickled to remove any oxides that
remain on the surface. Second the casting is removed with a saw,
snips
or cut off wheel from the button and sprues.

From this point forward there are many different procedures for
finishing a casting depending on the finish you would like to
achieve.

You may wish to file, sand, tumble, polish, hammer, hand texture,
burr texture, sand blast, engrave, satin finish, diamond wheel cut
and a whole list of other possibilities.

You must first know what you want your finished pieces to look like
and then you can choose the procedures that are needed.

If you don’t want to purchase any equipment to do the finishing
process than a possibility would be to buy a set of files and various
grits of sand paper and emery paper from coarse to very fine and work
the piece to a satin finish and then buff.

Good Luck

Greg DeMark
If You Like Antique, Vintage or Custom Jewelry
Visit us on the web at:
www.demarkjewelry.com

4

The first action with a casting is to remove the investment. The
larger portions can be picked or scraped off with a dental pick or
similar tool or brushed off with a brass brush.

The casting with the remaining embedded investment can be put into an
ultra sonic with one of the cleaner solutions designed to dissolve
investment.

If the casting was cast without a means to prevent fire scale the
casting is then placed in a pickle pot. This will turn the black
casting into a frosted white. See Orchids “Tips From the Jewelers
Bench” for how to prevent fire scale on castings which are vacuum
cast. The process is very easy. Contact me if you have any questions
about the process.

The spues are cut off. Any irregularity in the casting and the
remains of the sprues may be filed with a fine file or smoothed off
with an abrasive wheels in a cable driven hand piece. There are all
sorts of abrasive tubes and points that can be used to clean recessed
areas.

The buffing wheel will do a lot to clean up the project.

Lee Epperson

5 
what is involved in cleaning a casting

Hey Annabel, that’s a bit like asking how long is a piece of string
:slight_smile: - it depends on who does your casting, what stage they finish to-
if any, what the piece is, what your master is like and what finish
you require. Generally, you might need to saw off sprue remains, file
and refinish where they were, then polish or finish as you wish. If
the piece is moulded, you will probably need to clean off ( file,
sand) mould cutting lines. With sterling, you also might need to
clean off firescale - again depending on the casters and what alloy
they are using. You also might need to bend a few bits back into
shape, or work harden certain bits - depending on your original
design… Or some casters offer a finishing service, so you do
nothing except pay them!

have fun, Christine in sth Australia

6

Greg, thanks so much for your comments. I am thinking of sending my
first wax carving to a casting house, so I am presuming that they
will send me a fairly clean casting right? Also, I know what a sprue
is but what is a cut-off wheel and a button? They will pickle it and
do everything else automatically, right? I am talking about finishing
the casting. Can I use the same files I would use to file the wax to
finish the casting or do I need to buy seperate files?

7

Thanks so much, Neil! This is so helpful! I have tried to ask people
offline and they make it sound like it is rocket science and the
casting houses want up to $5 or more PER PIECE to clean the castings.
I would rather just figure out how to do it myself than pay all of
the
thousands that it might cost me to have someone else clean it for me.

8 
Can I use the same files I would use to file the wax to finish the
casting or do I need to buy seperate files?

Separate files - Usually wax files are much coarser than metal files
so the wax does not clog up the teeth. I use a no.2 cut file,
followed by a fine needle file then differing sand paper grades (
does depend what you are doing though) -

cheers, Christine in Sth
Australia

9

annabel,

A cut off wheel is a tool used in your flex shaft machine to cut
metal. This is not my first choice for removing sprues but it is an
option if needed.

When casting metal we need to use more metal than what the actual
piece requires for sprues and a button. A button is the part of the
casting that feeds the sprue and casting and looks like a cone shape
or button shape piece of metal.

Do not use the same files for wax and metal.

As far as what the casting house will do after casting depends on
the casting house and what services you have asked for. Some
automatically complete the whole process and others just cast and
return the raw casting.

I do casting work for the trade so if you need a backup source
please contact me off list at greg@demarkjewelry.com

Good luck
Greg DeMark
www.demarkjewelry.com

10 
Thanks so much, Neil! This is so helpful! I have tried to ask
people offline and they make it sound like it is rocket science>
you're welcome. very little in jewelry making is really rocket
science, its mostly common sense. It just needs to be demystified.
and the casting houses want up to $5 or more PER PIECE to clean the
castings. I would rather just figure out how to do it myself than
pay all of the thousands that it might cost me to have someone else
clean it for me.

Ah well, if you’re doing a volume like that it might well be worth
it to have them do it so you can concentrate on other things. But it
depends on your price point.