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Method for Removing Bubbles from Wax Injector Pots

Air and gas bubbles inside wax patterns can be a cause of rejects in finished castings. The major cause of air bubbles in injected wax patterns is water condensing inside the air compressor and the air lines to the wax pots. A moisture trap and filter should be installed in the air line just before the wax pot to prevent this problem. The devices are available from most suppliers of air compressors. The moisture traps should be drained on a daily basis along with the moisture traps on the air compressor. This will help keep water out of the wax pots. The following method is provided to remove bubbles from the simpler design wax injector pots. For the automated wax injectors, you may want to check with the manufacturer.

1. Shut off air supply to wax pot and disconnect air line.

2. Remove air supply line from wax pot.

3. Open wax pot and fill with wax to the usual level.

4. Turn on heat to high setting and allow wax to completely melt.

5. In the meantime connect rubber air line hose to air inlet on wax pot and attach to vacuum pump in the investing area.

6. Close and seal the wax pot.

7. Turn on vacuum pump and pull full vacuum for 2 to 3 minutes.

8. Shut off vacuum pump and disconnect hose to vacuum pump.

9. Open wax pot and give I shot of silicone mold release spray to break bubbles.

10. Turn down heat to regular wax injection temperature.

11. Close and seal wax pot, reconnect air line.

12. Allow temperature to drop to regular injection temperature before using.


1. Turn up temperature on wax pot. Open wax pot. Pour wax into stainless steel cooking pot.

2. Place cooking pot with wax on stove or hot plate at moderate heat.

3. Once wax is very liquid, place on heat resistant pad under vacuum jar in investing area.

4. Seal vacuum system and hold vacuum for 2 to 3 minutes.

5. Release vacuum and give I shot of silicone mold release spray to break bubbles.

6. Return Wax to injector pot, set temperature and seal the unit.

Suspect wax patterns can be checked under light to look for air bubbles or put in a box under vacuum unit in investing area, hold vacuum for 5 minutes and re-inspect waxes.

No guarantees are given for the preceding method which are given as information to UNITED customers. 

Precious Metal Spot Prices

  Bid Change
Gold $1,834.00 +$3.31/+0.18%
Silver $23.97 -$0.12/-0.48%
Platinum $1,026.21 +$12.01/+1.18%
Palladium $2,292.52 -$114.32/-4.74%
Gold 2020-12-03 11:59 AM
Bid/Ask $1,834.00/$1,834.78
High/Low $1,844.05/$1,823.78
Change +$3.31/+0.18%
Silver 2020-12-03 11:59 AM
Bid/Ask $23.97/$23.99
High/Low $24.28/$23.74
Change -$0.12/-0.48%
Platinum 2020-12-03 11:59 AM
Bid/Ask $1,026.21/$1,030.21
High/Low $1,037.51/$1,000.68
Change +$12.01/+1.18%
Palladium 2020-12-03 11:59 AM
Bid/Ask $2,292.52/$2,297.84
High/Low $2,422.94/$2,230.53
Change -$114.32/-4.74%

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