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Lost wax casting knowledge for designers


#1

I have lurked here for years now and sometimes even timidly ventured
a comment.

I’m asking for your help. I’m part of an artist’s group that meets
monthly to “play” in our chosen fields (mine is metal clay,
chainmaille, and I’m just now set up for some sheet silver and
copper fabrication).

One member of our group is a wonderfully talented and trained
sculptor who, for reasons of health and finance, has turned to
jewelry to express himself. Our group has unofficially “adopted” this
young man because of his talent and skill and we have done what we
could to help him, since jewelry construction was new to him. He
briefly worked as a bench jeweler many years ago and did wax carving
for his employer. Just recently he has carved some exquisite flowers
in wax with the thought of casting them in silver as elements of his
jewelry pieces. I suggested that he send me his questions and I would
post them on Ganoksin for responses since his limited computer access
made it difficult for him. I will convey to him any responses and
will appreciate any help you can give him.

i) What is a fair price for having jewelry pieces cast in Sterling
Silver ? I was quoted $3.50/gram at one place. And another place $75
for a large flask fee plus the cost of the metal. I’m not sure what
is A fair price. Can anyone advise me ?

ii) How can a person best get trained to do lost wax jewelry casting
in order to make producing their own work more economical ?

iii) How can a person get into lost wax casting of their own work in
sterling silver for a reasonable amount ? Can you find used
equipment?

Thanks for any help you can give.

Ann L. Lacava
Pure Silver Studio
Powell, TN


#2

Ann, I can’t really speak to your first question for a variety of
reasons -we cast but we don’t do what you are asking, basically.

The art of being a caster is complicated, like everything, but being
able to do simple castings for yourself is easy. Invest, burn out,
melt, let it fly… I had been in the business for quite some time
before I got a casting rig set up - not a novice - but still I just
did my first casting on my own. That’s having been around it over the
years… A person can pick it up pretty easily. Again, being a
casting expert is more…

The biggest hurdle is the equipment itself - there’s not much point
in gravity casting with most jewelry as your level of detail will be
limited, so you need vacuum and/or centrifuge and a kiln, and some
miscellany. Probably $1000 or $1500 new - or more, I guess. We still
use the first centrifuge that I bought from a failed venture for
$100. Bought the kiln for the same price, but we’ve been through 3-4
of those since. That isn’t years ago, it’s decades now… That and
some crucibles, flasks, investment and tongs and the like are really
the core of it all. Just went on EBay and didn’t see any great deals,
but you never know. Also try the vendors - I see Otto Frei has a used
kiln - try Gesswein, I Shor, others. They all have a used tooling
category…


#3

The first question that comes to mind is how big is a large flask? I
have flask 4"x12" that can hld 200-250 rings… $3.50 per gram
seems like a fair price for one and twosies… But a short run
production, that would be expensive.


#4

You can get started in lost wax casting for almost nothing. Steam
casting as an option is often overlooked. Basic equipment just to
get started can be made from a short length of wooden dowel, a jar
lid, a couple of terra cotta flower pots, an electric hotplate and
some small juice cans. You can upgrade from there as you go along. At
one time there was a couple who developed a kit with a more
substantial caster than the dowel/jar lid, and an improved base for
forming sprues. I use the system all the time for one off castings.

Jerry in Kodiak


#5
At one time there was a couple who developed a kit with a more
substantial caster than the dowel/jar lid, and an improved base
for forming sprues. I use the system all the time for one off
castings. 

Jerry, Do you remember who this was? I ran a search but didn’t come
up with anything.

Thanks,
Bobbie


#6

Years ago there was a casting unit available which was called
Vacucast, It was a box with a handle on it that one pulled to create
a vacuum. The flask was put into a recess in the box, the metal
melted in a cruicible formed in the flask, and the vacuum sucked the
molten metal into the flask. A friend had one and used it when she
only wanted to cast one item.

They seem to have disappeared from the market, though I heard that
they have been on ebay from time to time. Anyone know anything about
this caster?

Alma


#7

Bobbie,

No, I’m sorry, I don’t remember who they were. I believe the husband
was retired from the aircraft industry. They sold at shows around the
country, particularly Quartzite, for several years, then sold the
busines s to someone who ran it for a couple of more years. Haven’t
seen anything about it for fifteen years or so though. Probably
someone has a bunch of unsold kits in their garage somewhere though.
Wish I could find one, as I could use another sprue base former.

Jerry in Kodiak


#8

Hi Alma:

I think the summer estate sale fairies may have deposited one in the
school’s storage locker. I’ll see if it’s still there.

My memory of it was a simple box that you set the flask on, and
melted the metal into the button. Once it was molten, there was just
a little piston thingie you pulled on to generate some (very weak)
vacuum, to suck the silver down into the flask.

The one I looked at looked pretty wimpy. Even a tool geek like me
didn’t give it more than a glance before tossing it into the storage
pile.

Do you actually want one?

Regards,
Brian.


#9

Hi Alma,

I had a year at college many years ago and there was one there. I
thought it looked a bit of a toy, but the girl using it produced
some really delicate work. You could only cast 2" flasks but she cast
ping pong ball thickness and plastic mesh, the vacuum was created by
a thing like a track pump set up to pull rather than push.

regards Tim Blades.


#10

Thanks Tim. That is interesting to know. If they create enough
vacuum, it might be of value for some company to begin marketing them
again. Alma


#11

The casing system you refer might have been made by Ny craft. I have
a unit like this hooked to a vacuum pump with my investment unit. It
has a chamber for perforated flasks and several adaptor rings for
different diameter flasks. Also a flat plate with hole and rubber
pad for non perforated flasks. I could not figure out when I received
the unit twenty or so years ago what type of crucible to use so I
melt and pour by hand. I use for small melts of twenty dwts or less
other wise I use my J2r. When I need to replace consumables I have to
modify stuff, One thing I have learned over the years is purchasing
old equipment does not always result in cost savings if you have to
rebuild and modify, spend that time making your jewelry sell it and
buy what will make your life easy. Rio Grande has a more modern
version that is easy to service and has investing and casting all in
one unit, Even has a built in timer for investment mixing. This is
my first posting hope I was of some help.

Mark Guerin
http://www.harriscasadeoro.com


#12

Mark, The vacucast I was referring to is a small box, about 3" wide,
10 " long, and about 2" deep. It has a hole in the center into which
one set a small flask. One pulled the handle and long wire, extending
from one end of the box in order to create the vacuum. From what I
have since learned, it was difficult to get a strong enough vacuum to
really do the job.

It would be nice if someone came up with an improved version for
those interested in doing occasional small castings, without the
expense of major setup.

Alma


#13

Hi Alma

I was just working on a piece that I need to cast and didn’t want to
go through the hassle to set up the casting equipment that I had been
collecting over the past two years. Instead, I thought I would try an
experiment that even made me cringe, but it worked!

I carved a very plain band in wax, sprued it up with a big button on
the end. I then attached it to a plastic lid and taped an old soup
can to it (both ends cut off).

I then (prepare to gasp) took out my bag of plaster that I have been
using to make molds, mixed it up and poured it on the can with the
wax. I then let it sit up over night and in the morning popped it in
the toaster oven just over 300 degrees with a catch tray.

Once most of the wax melted out, I put my soup can on my soldering
station and heated it to burn out the wax residue (with the
ventilation on of course). I heated my silver up and poured it in.

I then headed down stairs and made a cocktail and by the time I made
it back to the “flask” I soaked it in water then chiseled out my
ring.

Surprisingly enough the casting turned out great! Completely solid,
no pits no air bubbles! The only thing that I would do differently is
add a vent to let the air escape, the actual pour was a little crazy
as the air was trying to get out while the silver was trying to get
in…

I hope to try it again with a more detailed piece to see what
happens…

Have fun,
Christine


#14

Hi Christine,

What a fantastic way to cast. Amazing what one can do with just
simple tools and a lot of creativity and imagination. Thanks for
sharing your success.

Alma


#15

Christine,

I initially experimented casting simple waxes without pulling a
vacuum when pouring the metal. I created vents by attached 18 gage
wire to the wax on the opposite end of the sprue. The wires were long
enough to stick above the top of the flask by several inches. After
the investment solidified I wrapped the ends of the wires around a
rod and pulled them out of the mold. The resulting holes left by the
removed wires provided vents to allow the trapped air to escape from
the mold as the mold as the silver was poured.

I have done the same thing with thinner gage wires on very
complicated waxes when pulling a vacuum.

It is fun to experimant.


#16

Christine,

Some days you can get away with anything, other times even when every
rule and technique is followed it is still not going to work. Nasty
casting goddess type stuff.

jeffD

Demand Designs
Analog/Digital Modelling & Goldsmithing
http://www.gmavt.net/~jdemand


#17

Christine, look up foundry casting of sculpture to see how to set up
a good gravity pour. Generally, the feed goes around the piece and
feeds into it from the bottom, and small wax wires lead from the
highest points in the piece to the top of the flask. It is easy to
see when all is full, because these tiny vents suddenly appear
metallic. It works great. You could assist with stem from a wet rag
or potato, if you like.

M’lou Brubaker
Minnesota, USA
http://www.craftswomen.com/M’louBrubaker


#18

Hi M’lou

Thanks for the comment.

I actually am familiar with foundry work and have poured some rather
large iron molds into sand castings and slip castings.

I just totally forgot about venting as I haven’t done a pour on this
scale or in silver or with plaster as a mold. Im going to do it again
next week and try to get a lot of detail in thin relatively thin
spots to see if it goes. I will try to remember to vent next time,
although its quite a show without them:)

Christine