Ventsi Posted September 17, 2010 Share Posted September 17, 2010 (edited) Me and a friend decided to build a small backyard furnace/foundry. We're going with the "2 bucks flower pot foundry" style. Any who , are any of you guys into this stuff? I've got a few quick questions: Green-sand, I understands its a mixture of sand, water, bentonite and sometimes powdered coal? What is the point of the coal, can AF charcoal be used? Also can you provide some formulas for green-sand? All of the websites I've looked on don't list any compositions. And last, can straight bentonite be used to get a smoother surface? Edit; I found some formulas seems that a common one is :10 100mesh Sand1 Fine Bentonite1 Water.4 Coal dust Edited September 17, 2010 by Ventsi Link to comment Share on other sites More sharing options...
dagabu Posted September 17, 2010 Share Posted September 17, 2010 (edited) Me and a friend decided to build a small backyard furnace/foundry. We're going with the "2 bucks flower pot foundry" style. Any who , are any of you guys into this stuff? I've got a few quick questions: Green-sand, I understands its a mixture of sand, water, bentonite and sometimes powdered coal? What is the point of the coal, can AF charcoal be used? Also can you provide some formulas for green-sand? All of the websites I've looked on don't list any compositions. And last, can straight bentonite be used to get a smoother surface? Edit; I found some formulas seems that a common one is :10 100mesh Sand1 Fine Bentonite1 Water.4 Coal dust You have to be careful of the type sand you use, silica sand is the standard. As far as the bentonite content, I find that it varies a lot depending on the pattern, the metal being cast so the content can vary up or down. I also add between 5-10% water to my sand before casting for finer detail. If you use more clay in your mix, you can get a reflective surface on Al if done right. I do not use any coal dust. I get my bentonite and silica from Continental Clay here in the cities. For really small pours, 1005 clay can be used but the heat makes the clay do strange things (powder and float in the surface, pop and fracture, alligator) so the silica takes up the heat and allows the clay to leave a nice surface. My dad (now 75) keeps telling me that the secret to casting is prep. Have fun! Edited September 17, 2010 by dagabu Link to comment Share on other sites More sharing options...
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