Copper ingots in sand Copper started welding to my steel ingot mold so I'm using sand. Had to drill out one mold and use a punch to get the ingot out, then weld up the hole. I spent more time trying to get it out by pounding on it than it did to drill, punch, and weld back.
I use sand molds for ingots too. Flipping the mini-loaf pan upside down and ramming it up like a match plate saves wear and tear on it vs pouring metal directly into it, and no risk of ingots getting brazed to it. Plus then I still have the pan handy if I'm melting Al and there's more left over than I expected... Jeff
I wonder if a layer of some kiln wash would help you not have that problem in the future? Some black soot should do the same thing me thinks...
Yeah, that was the reason. Based on something I read in CW Ammen's sand casting handbook. Added 1% dextrin (made it by baking corn starch) at the same time on a suggestion from HT1. Worked like a charm and boosted the green strength as well. I'm operating under that assumption that the (very temporary since the stuff burns out quickly) added green strength was due to the dextrin, and the no more sand stuck to the bronze was the seal coal. I later found out my old sand from Smelko's that never gave me any trouble at all probably contains sea coal and not dextrin but wood flour, which seems to last longer and have a similar effect from what I can tell. Jeff
Ah yes. My memory's coming back to me. That was quite an adventure. I'll have to revisit the thread. I have some bronze pours coming up but I have to clean up my sandy ingots first! Pete
I was having brazing problems until I stopped pouring ingots so hot. You just need the metal to be melted, not all the way up to pouring temperature. Richard
