Tried a new green sand mix at the Tacoma plant and got a nasty surprise

Robin Clark · 2026-03-22T08:45:06.281301+00:00

We swapped to a different bentonite supplier last month to save a few bucks, using a 50/50 mix with the old stuff. The first pour on a big gear pattern came out with major scabbing and gas holes, something we haven't seen in years. Turns out the new clay had way less bonding strength than the spec sheet said. Anyone else run into bad bentonite lately, and how did you test it?

simons286mo ago

Remember when cheap sand glue made our whole batch crumble like dry cake?

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jordan776mo ago

Ugh, that's the worst. We got burned the same way. Now we run a quick green compression test on a sample before we even unload the truck.

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uma6686mo ago

Yeah, that "way less bonding strength" is a killer. We do a simple methylene blue test now on every new batch before it even hits the mixer.

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