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Lost wax casting - wax - silver weight ratio


I have a question about lost wax casting: what is the correct weight
ratio between the wax patterns and the weight of the silver to be used
for casting. In other words how make sure I have the correct amount of
silver for casting when I only know the weight of the wax casting
patterns? Richard


To get the weight of any casting material, multiply the weight of
your wax by the specific gravity of the metal you wish to cast in;for
silver this is approx 11(ie 1 gram of wax would yield 11 grams of
sterling) cheers,chris


Richard, the specific gravity of silver is 9. Multiply the weight of
the wax times 9. Ken Sanders


Richard, the correct weight is 10.4… I usualy just go ahead and
multiply the wax by 11. Good luck, Andy Cooperman


Richard, weigh your wax in grams, multiply that number by 10.2… that
will be your weight in silver… I always add 10 grams to the toatl for
the sprue button… Marc Williams


Hello Richard, Multiply the weight of the wax by ten the get the
amount of silver neccesary to make the piece. Thirteen and a half for
fourteen karat, fifteen for eighteen karat and twenty for platinum.
Always add a bit for the sprue. Have fun. Tom Arnold


I use the wax as a specific gravity of one. , This must include
the weight of the model , all feed spruing and vents including the
feed button. This times the specific gravity of the metal to be cast
gives the minimum weight to melt. Melt a little more. Be sure your
sprue system is adequate to provide for shrinkage in the heaviest
section. Jesse


Hello Richard: The wax weight multiplied by the “specific gravity” of
the metal you are casting in multiplied by a factor of 1.1-1.2 for the
sprue. In this case , Sterling silver has a specific gravity of 10, so
wax weight times 10 times 1.2 equals metal needed. I use a vacuum
caster. Many of the jewelers supply catalogs have a chart of specific
gravities of metals in the back.

Michael R. Mathews


The weight of the wax may vary and cause you to miscalculate. It is
easier to use displacement. It works for all metals. Use a graduated
cylinder or a narrow glass. Fill it half way to top. Submerge the
wax. I attach the wax to a thin wire and sink it. Mark where the new
level of the water is. Pull out the wax. Add the metal you want to
use until you match the line. Don’t forget to add some for the sprue
and button. Always works for me. Steve Ramsdell


Richard: I usually weigh the sprue base before I sprue waxes or even
add the main sprue. I put a spot of white out on the bottom of the
base and write the weight on it after it dries. then I sprue as usual
and weigh the finished base. Subtract the starting base weight from
the finished weight and multiply by a factor of 10. this gives the
weight of the silver to fill the casting. Now add the amount of
weight you need for a back sprue or button and you have the weight of
silver to make the casting. For 14kt gold I use 13.5 and 15.5 for
18kt. these a round numbers and not exact conversions. They are easy
to remember. Also the number you wrote on the bottom of the base is
usually good for two or three castings in case you forget to weigh
before you sprue. Frank Goss


Are you looking for the individual weight from a wax pattern or are
you trying to determine the weight needed to cast the item. If all you
want is to convert the wax to silver and not cast the item I would
multiply the wax weight by 10 ( approx) and this will give you grams
or dwt depending on the scale you are using. If you want the amount of
metal needed to cast the piece, this is what i do.

  1. weigh the rubber base with no wax or tree on it.

  2. use a small burr and grind the base weight onto the rubber base so
    you will never need to weigh the base again. 3)grind a number onto the
    base if you have more than one base. (1 to 100 will do)

  3. put your tree (wax rod ) into the base and weld a sprue to the
    item you want to cast… then weld this Item to your “tree”

  4. Take a piece of paper and label it tree # 1 (if you are casting
    more than 1 tree.)

  5. Weigh the base with all the parts and the tree,Subtract the base
    weight which leaves the wax weight… Multiply by 10 to achieve the
    silver weight, then add an extra 30 grams for the button of the tree.

  6. in other words…

Total weight - base weight = total wax weight x 10 =silver weight +
30 grams for the button.

  • after you have invested your tree, and the investment has
    sufficiently dried (1 hr) remove the base and scratch the base number
    onto the top of the investment lightly This so you will know which
    tree to cast if you have more than tree.

Hope this helps.
Daniel Grandi


multiply your gram weight of your wax model x 10.5 + 50% extra for
the button and you should be good to go


Richard–you weigh the wax with sprue attached and then multiply by
the specific gravity of the metal you are going to be casting. For
sterling silver it is 10.36 and you should also add about 10% for the
button. Just in case you decide to cast 14k gold it is 13.07. Happy


Hi ,if wax weight .5 dwt , multiply the weight by 10 and you must
include the sprue when you weigh the wax. Have a nice day. JD.