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Vent: My home castings always have blowholes...

Trying to make decorative knobs from scrap aluminum. Every piece comes out with tiny holes... it's making the surface look terrible and I can't figure out why.
3 comments

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3 Comments
jessica_owens10
Preheating my mold and drying the scrap first fixed those blowholes for me.
5
noahward
noahward4h ago
Ever think about what you're using to preheat? @jessica_owens10 that drying step is key, but if you're using a propane torch on the mold, you might be adding moisture back in from the flame's exhaust. That hidden dampness could still cause tiny pits. Try an electric heat gun instead to keep everything totally dry.
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rileypatel
Got the same problem, degassing the aluminum before pouring fixed it for me.
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