Hi....I've been trying to pour 1oz sterling bars with not a great deal of success. The pic is the best to date. The silver melts really well and is very liquid but the problem occurs when I pour into the graphite mould. Even after heating the mould I don't seam to be able to get the silver into all four corners. Any help, wisdom, thoughts, winning lotto numbers would be gratefully received. Thanks very much GF
My usual solution is to cover everything in render to hide the blemishes, in this case I would grind everything back until you got the shape you were after. I think it is a case of more heat is needed. You don't seem to have any ripples in the bar so it looks like the silver is hot enough. Probably needs more heat on the mould. I will let someone with real life pouring experience give you some proper advice though... Are you melting down old pre dec coins or scrap silver? I keep thinking I should have a go one day but it looks a bit harder than I thought.
Thanks Fellas...its .925 scrap (xrf test .940) Big Steve..currently using a map torch at 5000 degrees to heat the mould. I might need to rethink the whole process..
I cast lead a lot, ingots, bullets. Your bars are exhibiting signs the mould is too cold. You need to pre heat and apply post heat to allow the molten metal to cool slowly. Without out the heat you get poor fill out and shrinkage. Having never used graphite I don't know how much heat the will take. If you have a gas ring place the mould on a piece of steel plate on a bbq burner and apply lots of heat to the mould. Also looks like there is slag in there. do you flux? Is the crucible clean?
Thanks Russ. There is no slag, its just a crap picture. Seems heating the mould more efficiently is the key. Will work out a solution and post the results. Thanks again everyone
just as an idea, it will end up costing a bit in gas but buy a second mapp gas burner and have it heating the mold at the same time using the second one to melt the silver - apart from that making a furnace and having the mold sitting in that
agree with SAbogan 2 torches 1 flame over mold hotter the better and soot your mold! as its sterling u need flux BORAX or borax mix soda ash works just fine pour quickly keep flame on the silver till it start to harden you should get a good result takes a bit of practice to get right see some of my previous threads for pics have FUN look forward to seeing some of your work feel free to PM me if you got any Questions i will help if i can humbolt
Not yet Humbolt. I'm still having issues getting the silver into all corners of the mold. I have a plan....will post when I get it right.
If you want to get it in all corners there is 2 things you need to do. One is the mold isn't getting hot enough so the silver is cooling too quick and not filling the gaps. Second have the mold sideways like how the bar is sitting in your photo and pour it in the middle. Hope this helps
Yep, More heat. Cold mold=poor fillout cold metal=poor fillout wrinkles on the metal =too cold (mold or metal) Russ
