Very tricky of you to figure out it isn’t "linearily dependent "
with only 2 points of reference & no known zero point. I’ve no
idea how they came by gauge designation, but now I’m curiuos &
shall check in electrician ref manual & “Complete Metalsmith” to
see if I can find out. I asked my math major linear Ken (he
does model railroads and they’re in gauges too, seemed like a
logical progression) but he doesn’t know either. I cheated &
looked up conversion table in Tripp’ s MFG catalog, but while
searching for answers I found this on the web http://www.kitco.com/chart.ga2mm.html which is conversion table
for inches, mm & gauge. Happy to be able to contribute
something constructive, Kat
Does anyone have a weight conversion table for a wax model to
finished 14k or 18k gold item? There must be a better way than
submersing the wax in water, adding the equivalent in gold and
weighing it. Thanks from infront. Anna
Hello Anna, Weigh your wax. Multiply by 13.5 to get the weight
in 14k and 15 to get the weight in 18k. Multiply by 10 to get the
weight in sterling. Have fun. Tom Arnold
There is. you need an accurate scale/balance though. I use a
diamond/gemstone balance. convert carats to grams by dividing by
five…
Wax has a specific gravity/density of about 1, essentually the
same as water. All you need is a table that shows the specific
gravity of the metal you’re casting. Multiply the weight of the
wax by the metals density, and you’ve got the weight of the
finished casting. Most 14K yellow alloys, for example, have a
density of about 13 to 13.5. A wax model that weighs 5 carats,
or 1 gram, can then be estimated to weigh about 13.5 grams when
cast. You need to add for the sprue, of course. 18K yellow
golds are a bit heavier, with a density of about 15.5 to 16.
(variations depend on the exact proportions of alloying metals,
since silver is denser than copper, which is denser than zinc,
etc.)
Hi Anna, The formula I use for casting 14k is wax model plus
sprue =12x gold. For 18k sprue plus wax =15x. Add a little extra
for good measure. Marty Rosenblum
Hello Anna Take the wax, weigh it on a very accurate scale. for
silver, multiply the wax weight by 10 for 14k gold… many
people mulitply by 13. 5 ( i use 14) for 18k i multiply by 18 I
do a lot of casting for many different designers and stores if
you should need it.
Anne as a general rule of thumb multiply wax weight with a
factor of 12.9 for 14kt and a factor of 15.10 for 18kt. For
example if your wax model weighs 1.2 grams, 14kt weight would be
1.2 x 12.9 = 15.48 grams in 14kt. Hope this helps P.S. I have a
table that I could scan and mail you. Lawrence in rainy South
Africa
Does anyone have a weight conversion table for a wax model to
finished 14k or 18k gold item?
Dear Anna, Here is the table I have used for years:
Sterling wax wgt X 11
10K white wax wgt X 12
10K yellow wax wgt X 13
14K yellow, white and red wax wgt X 14
14K green wax wgt X 15
18K white wax wgt X 16
18K yellow and green wax wgt X 17
22K yellow wax wgt X 21
10% Irdidium Platinum wax wgt X 24
Anna just multiply the wax weight by the specific gravity of the
metal your using. The specific gravity of 14ky is about 13.5,
18ky about 15.6 different alloys slightly different s.g.'s. I
like to add a mininmum of 25% additional for sprue. The more the
merrier but that gets expensive.
You can find the info in places like Stuller’s Metals Book, Tim
McCreight’s, “The Complete Goldsmith”, Hoover&Strong’s website,
etc.
Does anyone have a weight conversion table for a wax model
to finished 14k or 18k gold item? There must be a better way
than submersing the wax in water, adding the equivalent in gold
and weighing it.
Hi Anna, Place your wax model on a gram scale with your sprue
attatched. Multiply that by 10.4 for silver, 11.6 for 10k, 12.6
for 14kw, 13.4 for 14ky, and 15.6 for 18ky. These are the
specific gravities for these metals. As best as can recall
anyway. Hope this helps. Almost forgot, add about 5 grams for
your button. Michael B
Anna -what a beautiful name…multiply the weight of your wax
(regardless of which kind of wax) by the specific gravity of the
desired metal. Here is a list of the most common alloys and their
specific gravitys (sic):
Gold: 24kt. 19.36
18kt 15.5
14kt 13.4
Silver: sterling (.925) 10.46
Of course there are variations of weight depending on the alloys
used. For example the difference between a nickel or palladium
white gold. But you can use these calculations as an
approximation. Good luck. Kim-Eric Lilot. In San
Francisco…experiencing the onset of La Nina.
This is found in Murray Bovin’s “Centrifical or Lost Wax Casting
for Schools, Tradesmen and Craftsmen.” Simply weigh the wax(s)
with sprues attached and multiply by the specific gravity given
for the desired metal and you will have the weight of your
casting (with sprues). I never liked the water displacement
method eather.
Aloha Anna, I may start a long discussion here,with this one.
But,here goes. The specific gravity of wax(most waxes and
plastic) is represented as 1.The specific gravity of metals are:
Different alloys (white, rose, green, etc.) of gold, platinum
and silver have different specific gravities. Get a chart from a
good reference jewelry book. What I usually do is weigh the sprue
base(first,before attaching the base), and the wax tree attached
to the base (after it is attached) and the base. Subtract the
weight of the base, multiply the result (wax weight less base) by
the specific of the metal desired, and add 15% (to 20%) for the
push (sprue). So if a wax weighs, 1.5 grams and I want it in 18k
(yellow), 1.5 gms. x 15.6 = 23.4 gms. + 15% = 26.9 gms., to make
the piece. Hope this is of help and I explained it to your
understanding.
Regards,
Christian Grunewald
Precision Modelmaking
Hawaii
Anna, what you need is the spacific gravity of the metals you
want to use, or round it out .For example for casting a silver
ring ; wax wt. .5 dwts. x sterling silver S.G. which is 10.4 or
just round it out to 10. = 5 dwts. then add extra for a button I
always add more than less and the more pieces you cast at a time
the more extra metal you’ll need, I’d at at least 10 more dwts .
to the 5 just to be safe. Specific Gravity’s 14k =13.4 S/S =10.4
Hope this helps, Matt the Catt
yeah well your right as far as the conversion goes…but if you
add to much for the button in the casting…you will get what is
known as "draw porosity. The button as it cools pulls at the rest
of the casting, as it does it draws molten metal to it. It is an
uneven pull and you may find prongs breaking, tiny defects,
little missing parts of a bezel. Trust me on this I wrote the
book on casting. A 5dwt button max. mp
Hello Anna: I have been taught to add 20 to 25 percent of the
required cast metal weight for the spue button. An example would
be:
Wax weight = 1.0gr. casting in sterling silver would be 1.0 x
10.4 = 10.4gr. 10.4 x 1.25 = 13.0gr. Casting 13 gr. of silver
would be 25% extra for the sprue.
There is a good old book by Murray Bovin called “Centrifugal or
lost wax jewelry casting” that you might want to get. It has the
you seek.
