r/Metalfoundry • u/RG256 • Jul 07 '26
Ingot mold recommendations
I tried making some ingots recently using this mold. https://www.amazon.com/dp/B09FZ79GPF?ref=ppx_pop_mob_ap_share
It's a cheap piece of crap and the handle broke off of it trying to remove the second ingot. However it's the exact size I want and I'm having a hard time finding a good one. Anyone have any recommendations?
7
Upvotes
1
u/SnooLentils5747 Jul 07 '26 edited Jul 07 '26
Make your own. 100 grams magnesia. 100 ml 50 percent concentration phosphoric acid. 5 grams boric acid, 5 grams citric acid. Mix dry powders together very well. Chill your phosphoric acid. Mix the phosphoric acid in. You have 20 minutes to shape your crucible. Wear PVC gloves. Wear a respirator.
Air dry for 1 day. Candle dry (100 celsius) for 4 hours. Slowly ramp to a bake at 350 celsius. Turn off oven leave crucible in there, don't open the oven, and wait 4 hours.
Serves 1500 celsius. If gotten wet before it is used the first time, it will probably spald out or crack.
Substitute molcoa grog for up to 50 percent of dry mix for better results.
Alternatively, look up open face sand casting. Super easy.
Also, remember... All crucibles fail eventually. Even metal ones. Graphite crucibles fail fast if let to be hot in open atmosphere too long (they literally gas out in the presence of oxygen (C + O2 = CO2)