fiona_kim•1mo ago

PSA: I was wrong about skimping on molding sand

I thought it was a waste of money. A perfect casting proved me wrong.

4 comments

4 Comments

caseyf321mo ago

Grit size matters in molding sand. What number gave you that perfect cast?

paulw531mo ago

I saw in an old foundry manual that 80-grit silica sand is a good middle ground. It said that finer grits, like 100, can give a smoother surface but might not let gases escape as well. For larger casts, coarser sand around 60-grit helps with venting but can leave a rougher finish. The manual suggested mixing different grits for complex shapes, which I found interesting. Have you tried blending sands to see if it improves your results?

jessej231mo ago

Actually, my buddy mixed 80 and 100 grit for a detailed cast last week. Said it vented way better and still came out smooth. He's gonna stick with blends from now on.

morgan_king369d ago

Wait, are we still talking about sand or did I just walk into a coffee shop? I tried 70 grit once and my cast looked like it was made of oatmeal. Then I went to 100 and it was so smooth the metal wouldn't even stick to it. Now I just use whatever's left in the bag from my kid's sandbox, which is probably a blend of sand, cat litter, and old cheerios. It works about as well as my other plans.