My old sand mix vs the new pre-blended stuff at the yard

I spent my first 5 years mixing my own sand for the green sand molds. Had a system with the bentonite and water that worked okay most days. Last month the supply yard pushed me to try their pre-blended mix at $28 a bag instead of $18 separately. First mold I packed with it held shape way better and cuts came out cleaner. No more guessing if my moisture content was off or if I added enough clay. Second pour had way less inclusions in the casting surface. Has anyone else made the switch and stuck with it or went back to mixing your own?

2 comments

2 Comments

thompson.christopher1mo ago

I mean, I get why it seems easier but mixing your own gives you way more control when the weather changes or you're working with different metals. Pre-blended is fine for consistency until you hit a humidity spike and realize you can't adjust it on the fly. Maybe it's just me but I'd rather trust my own recipe than a bag that could vary batch to batch.

thompson.christopher1mo ago

I gotta push back a little on the "could vary batch to batch" thing cause that's actually the whole POINT of pre-blended. The big suppliers test every batch for moisture and clay content before it goes out, so it's way MORE consistent than what I can do at home with my garden hose and a bucket. Last summer I had three straight days where my mix felt different each morning just cause the humidity changed. Pre-blended takes that guesswork out. I've been on it for six months now and every bag I've opened feels identical. My casting surface is smoother too, less of those little gas holes I used to fight.