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Sulfur Gas

The effects of sulfur dioxide gas and the porosity it causes has been researched with definitive reactions identified. The most common reaction in all alloys is where calcium sulfate &carbon are in a neutral or reducing atmosphere at 700 degrees C and above. The reaction can and often does occur in electric burnout ovens as well as gas ovens.

The side effects of sulfur gas have some particular reactions on silicon deoxidized alloys. In 14 karat yellow gold the effect is seen as a rough dendritic surface. Finished castings may show a cloudy surface texture with small round holes. In some extreme cases cracking has been seen. The sprue (tree) will show a very rough dendritic structure on the inside button, and may be dendritic farther up the sprue (tree).

The effect of sulfur gas on nickel white gold with silicon, appears to promote a silicide of nickel and silicon, NiSi,. This conversion seems to correlate directly with sulfur gas porosity.

Conditions that may cause conversion of sulfur gas:

Elimination of sulfur gas conversion:

Precious Metal Spot Prices

  Bid Change
Gold $1,265.19 +$0.64/+0.05%
Silver $17.33 +$0.08/+0.46%
Platinum $944.00 +$2.00/+0.21%
Palladium $813.00 +$2.00/+0.25%
Gold 2017-04-28 2:19 AM
Bid/Ask $1,265.19/$1,265.29
High/Low $1,266.00/$1,263.10
Change +$0.64/+0.05%
Silver 2017-04-28 2:19 AM
Bid/Ask $17.33/$17.34
High/Low $17.38/$17.24
Change +$0.08/+0.46%
Platinum 2017-04-28 2:19 AM
Bid/Ask $944.00/$950.00
High/Low $950.00/$941.00
Change +$2.00/+0.21%
Palladium 2017-04-28 2:19 AM
Bid/Ask $813.00/$823.00
High/Low $823.00/$812.00
Change +$2.00/+0.25%

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Prices shown are for reference only. Please contact our trading desk for accurate, up-to-the-minute pricing.