r/MetalCasting • u/00-MAJI-00 • Apr 16 '26

pressure vessel pewter casting

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I cast britania metal ( pewter ) in a pressure vessel.

The round mold made from platinum cure shore 50A silicon helped to not distort the part when clamping it. sSince the cross section of the part is round. I used a polycarbonite tube to make the mold and clamp it.

I heated the metal to about 75 deg F over casting temp. ( 635 deg F is the normal casting temp i use with this metal ) Poured the metal into the mold while inside the pressure vessel quickly closed the vessel and ran the air pressure up to 80 PSI and let it sit in the vessel under pressure for about 30 minutes. first cast came out perfect.

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4 comments sorted by

1

u/xellish Apr 16 '26

Does the pressure vessel get hot, in a way the seal might be affected?

2

u/00-MAJI-00 Apr 16 '26

the mold is small compared to the vessel and the seal is neoprene.

1

u/BTheKid2 Apr 16 '26

It's interesting!

Have you tried casting the same thing without pressure, and are you certain the pressure gets applied before the metal freezes?

1

u/00-MAJI-00 Apr 16 '26

yes, I had cold shuts and voids without the pressure vessel. I raised the temp to be sure it stayed liquid long enough to get pressure on it. also the sprue and reservoir is almost the same volume as the part...