ALLOYS WEBSITE FAQ/Troubleshooting
SHORT CASTINGS OR INCOMPLETE CASTINGS
CHECK WAX THICKNESS
 Should be 0.3mm minimum. Bridgework is typically waxed to 0.5mm minimum.
CHECK BURNOUT TEMPERATURE
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Should be within 25°F of our recommendation.
If everything else checks out, raise in 25°F increments.
CASTING FORCE
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For spring wound machines, typically use 2 turns for C&B gold and high gold PFM, and 3 turns
for Au-Pd, Pd-Ag, high palladium, and Ni-Cr.
While miscasts due to insufficient force are more common, miscasting can result from excessive
force due to mold gas back pressure.
Broken arm should swing easily.
SPRUING
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Smooth crucible formers improve castability.
Sprue for metal flow.
No more than ¼ inches investment over the tops of patterns.
ROUGH CASTINGS
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Debubblizer must be dried prior to investing. Wet debubblizer can contribute to investment
breakdown.
ONLY mix investments with special liquid and DISTILLED WATER. More investment related
problems are caused by the use of tap water than you would possibly believe.
Check burnout rates, temperature and hold times. Watch out for excessively slow or fast rates,
extra long hold times, or extreme temperatures - all can contribute to investment breakdown.
Check investment mixing technique. Specifically, spatulation time should be within
recommendations (typically 1-2 minutes). Special liquid concentrations should be within
recommendations as well.
Follow recommendations for setting time. Do not rush setting time, and do not remove crucible
former prematurely.
Look for trends. For example, are all castings rough or just some? Which ones? Those invested
in the morning or the evening? Singles or bridges? Those from small diameter rings or large
ones? etc.
Keep separate mixing bowls for gypsum and phosphate materials.
Is the inside rougher than the outside? Try a different die lube.
If the problem came on suddenly, make a casting from all new metal. You may have a
contaminant.
CASTINGS TOO TIGHT
Increase the concentration of Special Liquid.
ALLOYS WEBSITE FAQ/Troubleshooting
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Decrease the total liquid volume 0.5ml.
Use an extra layer of ring liner.
CASTINGS TOO LOOSE
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Decrease the concentration of Special Liquid.
Increase the total liquid volume 0.5ml.
POROSITY
Shrinkage porosity irregular in shape, usually in the thicker sections and up near the sprue. Spongy
appearance to the metal.
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Improving the spruing will solve 95% of the shrinkage porosity problems that technicians
encounter.
Excessive burnout temperature will contribute to shrinkage porosity.
Gold C&B alloys
900-1200°F
Silver-Palladium C&B alloys
900-1200°F
Gold-Platinum PFM alloys
1300-1400°F
Gold-Palladium PFM alloys
1400-1550°F
Palladium and Palladium-Silver
PFM alloys
1400-1550°F
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Excessive casting temperature will contribute to shrinkage. Improve the torch adjustment and
check your casting indicator.
GAS POROSITY
Round in shape, no specific location on the casting. Frequently subsurface.
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Check your torch adjustment and tip condition. Poor adjustment or flame condition is the most
common cause of gas porosity.
Preheat crucible with torch prior to placing alloy in the crucible.
Replace worn crucibles.
Always add fresh metal when casting.
Ensure complete burnout.
ALLOYS WEBSITE FAQ/Troubleshooting
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Do not overheat. With most alloys, we cast when the alloy becomes a ball that no longer sticks to
the sides of the crucible when we jiggle the casting arm. With Castell and State, we cast before
the alloy forms a ball. Nickel-Chrome alloys should be cast after the ingots slump (never break
the oxide on Ni-Cr!).