oldnewprobs Posted February 18, 2023 Share Posted February 18, 2023 So I'm using c w Amen 's casting book as a reference, and he suggests a few green sand ratios in it. Most are close to a lot of what I see online, but his recipes for aluminum calls for nearly twice as much clay,19%, 8% moisture, which implies 19:73 clay to very fine sand ratio. His light brass suggestion is 13% clay and 8% moisture, which is more like most recipes I see. Heavy brass is 9 and 7. Most recipes I see online are more like that, generally 1:9 clay to sand. This is close to double and I'm struggling to manually combine this stuff evenly. I'm tempted to cut it with some sand to ease mixing, or should I stay the course? Quote Link to comment Share on other sites More sharing options...
George N. M. Posted February 18, 2023 Share Posted February 18, 2023 I'll just point out that moisture should not, IMO, be added into the clay/sand ratio. The water just occupies the pore spaces between the clay and sand particles and is not part of the basic mix. It only allows the particles to adhere to each other and not just be loose dust and sand. So, your Amen recipie would be 19% clay and 81% sand. The water/moisture is apples to the clay and sand's oranges. The damp clay is the binder which helps the sand particles bind to each other. I'm not sure how you would measure the moisture persentage without some sort of a hydrometer. 100% moisture would be the maximum which could be taken up in the pore spaces with no liquid left over. This would vary with the size of the sand grains and the type of clay used. It is possible that a foundry reference may use weight of water compared with the weight of the dry ingredients as a proxy for actual percentage of water by volume in the mix. I should say that I am not a casting guy, just an old geologist who has worked with sand/clay ratios in sedimentary analysis and in drilling muds. "By hammer and hand all arts do stand." " Quote Link to comment Share on other sites More sharing options...
oldnewprobs Posted February 19, 2023 Author Share Posted February 19, 2023 Haha a kindred spirit. I couldn't for the life of me decide which way to interpret these charts. I know final moisture is not too hard to establish empirically so I'm not like planning on weighing it out, but it lets me know that my starting moisture is about 4x what I need, since I started with chips and needed to get them in solution to be able to combine them with the sand, which I dried thoroughly to have a decent starting reference. Actually here's the relevant section, I'm curious about anyone on here's opinion Quote Link to comment Share on other sites More sharing options...
George N. M. Posted February 19, 2023 Share Posted February 19, 2023 I beleive the "fineness" is US mesh sizes which is how many holes per inch. The approximate conversion from mesh to microns for the sizes given in the reference is as follows: Mesh Microns (approx) 175 85 111 135 73 200 108 130 218 70 232 62 Size in fractions of an inch or millimeter can be found on line. "By hammer and hand all arts do stand." Quote Link to comment Share on other sites More sharing options...
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