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Casting Information

Porosity Prevention

The single biggest problem confronting the caster is porosity. By observing a few simple guidelines, porosity can be kept to a minimum.

Sprue Size

As a general rule make the sprues at least as heavy as the heaviest section of the casting. Metal shrinks as it solidifies, and if additional molten metal is not available to fill in a void will result. If the sprue is too thin, it will solidify before the casting, thereby cutting off the supply of molten metal to the still molten sections of the casting.

A common mistake is to have a large sprue that is necked down at the point it attaches to the cast piece. This restriction acts like a nozzle and causes turbulence as the molten metal enters the mold. The sprue should be uniform in thickness up to the point where it is attached and there it should be flared in to insure a smooth and uniform flow of metal into the casting.  Metal flow into the cast pieces should be as straight as possible.

Sprue Location

Attach the sprue to the heaviest section of the casting. This allows the heavier section to be "fed" after the thinner sections have solidified. Multiple sprues are sometimes necessary if the casting has more than one heavy section.

Always place the heaviest pieces closest to the button and the lightest pieces at the other end, where there is more pressure to promote better filling. Also, the casting should not be placed too close to one another on the tree. When pieces are too close, localized heating of the investment results in poor heat extraction.

Melting Practice

It is very important to protect the metal from oxidizing and absorbing unwanted gases. Protecting the metal from contacting the air can be achieved many ways:

  • With a fuel rich gas flames
  • With a protective inert gas such as nitrogen or argon
  • With flux

Heating the metal to the proper temperature is a critical factor in obtaining good castings.  When the metal is too cold, it freezes in the mold before completely filling it.  When the metal is cast too hot, shrinkage porosity occurs in the heavier sections or immediately adjacent to them. 

Overheating the metal can cause base metals (primarily zinc) to be "burned off" or evaporated. As the base metals are lost, the percentage of gold (karat) increases. Each time the alloy is reused some of the special de-oxidizers are also lost. To minimize losses, keep close watch on metal temperature and always use at least 50% to 75% new alloy.  We strongly discourage adding pure zinc or alloy to compensate for losses.

Temperature Chart



Flask Temp

Cast Temp

Liquidis Temp

Wax Factor

Product ID 


 10 Karat

1000°F -1100°F 

 1925°F 1865°F 12 10WCG 
 14 Karat 950°F - 1050°F  1900°F 1785°F  14  14WCG

 14 Karat W/ Palladium

1050°F - 1150°F 2050°F  1880°F   14  14WCGPD
 18 Karat 900°F - 1000°F  1850°F  1725°F  16  18WCG
 18 Karat W/ Palladium 1050°F - 1150°F  2160°F  1895°F  16  18WCGPD


 10 Karat 850°F - 950°F   1760°F 1635°F  13  10YGS 
 14 Karat 950°F - 950°F  1725°F  1605°F  14  14YGS

 14 Karat Satin

850°F - 950°F  1705°F  1605°F  14  14YHH
 18 Karat 900°F - 1000°F  1820°F  1725°F  17  18YCG
 22 Karat 1000°F - 1100°F  2000°F  1850°F  21  22YCG
 24 Karat 1000°F-1100°  2090°F  1947°F  22  24K


 14 Karat 900°F - 1000°F   1650°F 1535°F  15  14GCG 
 14 Karat Green/Yellow 900°F - 1000°F   1750°F  1605°F  14 14GY 
 18 Karat 900°F - 1000°F  1875°F  1725°F  17  18GCG


 14 Karat 950°F - 1050°F  1975°F  1715°F  14  14RCG
 18 Karat 1000°F - 1150°F  1875°F  1673°F  17  18RCG

 Extra White

 10 Karat 1000°F - 1100°F   2025°F  1865°F  12  10WXCG
 14 Karat 1000°F - 1100°F  1950°F  1730°F  14  14WXCG
 18 Karat  950°F - 1050°F  1922°F  1702°F  16  18WXCG

MJSA and World Gold Council White Gold Task Force

In 2004, the MJSA and World Gold Council assembled a task force to determine how best to measure the color of white gold and report the color in a single easy to interpret numerical value, and design a series of voluntary standards with which to categorize white gold and it's need to receive rhodium plating. The task force defined the following grades of white gold, determined by their ASTM YI:D1925 value (a mathematically determined value which is calculated from tristimulus color values.)


Grade 1

Grade 2

Grade 3

Non White


Good White Reasonable White Off-White Poor White

YID:1925 Range

Under 19 19 - 24.5 24.5 - 32 Over 32

Rhodium Plating

Not Needed Optional Required N/A (non-white)

G&S Metals has several white casting grains available, our extra white casting grain products are all "Grade 1" and are available in 10 Karat, 14 Karat, and 18 Karat. They do not require rhodium plating to achieve a good white color.

This can be confusing because sometimes Alloys are referred to as Casting Grain Alloys. This may be oversimplifying but what’s important to remember is that:

Alloys are what you combine with 24K to change the color and karat.

They contain no precious metal; hence the cost is considerably less than casting grain.

Casting Grains combine the alloy with 24K gold to produce the various colors and karats.

About Casting Grain

Wholesale casting grain is available in 10K white gold and 10k yellow gold. 14K casting grain is available in yellow gold, white gold, green gold, red gold and greenish yellow gold. 18K casting grain is available in yellow gold, white gold, white palladium gold, green gold, and red gold.

Our 14K Extra White and 18K Extra White contain higher nickel content than traditional white casting grain, and do not need rhodium plating to achieve a good white color. The process of manufacturing with this grain achieves a desirable color and workability.

Yellow Casting Grains contain a higher percentage of copper, with smaller amounts of silver and zinc. 

Red Casting Grains contain a higher percentage of copper than yellow, with silver and zinc. 

Green Casting Grains contain a lower percentage of copper, higher percentage of silver, with zinc. 

White Casting Grains contain copper, zinc and nickel

Extra White Casting Grains contain copper, zinc and a higher percentage of nickel.


Platinum casting grain is available in 90/10 Platinum/Ruthenium and 95/5 Platinum/Iridium.

Palladium casting grain gives you the look of platinum at a fraction of the price and is gaining favor once again in the manufacturing of wedding bands.


Silver is available in Sterling Silver Casting Grain, Fine Silver Casting Grain, and Argentium® Silver Casting Grain. Argentium® silver casting grain is available in .935 and .960 silver and is an anti-oxidizing, fire-scale free casting grain that is extremely tarnish resistance.

Manufacturing procedure for casting grain:

Casting and Flask Temperatures:

The most important element of casting grain is consistency: consistency of color, the consistency of performance and the consistency of results. This is what you expect and this is what you receive from G&S Metals casting grains.

Our casting grain prices are competitive and we are continually expanding our product line to meet your needs. We strive to produce casting grains in a variety of color, karats, and metals with the same consistency of performance.

Whether your needs require traditional 14K yellow casting grain or no-rhodium plated 14K Extra White casting gran, you’ll find the casting grain of your choice ready for immediate delivery at G&S Metals.


All prices in our shopping cart are based on the London PM Fix and change daily.

Prices are subject to change without notice.