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FWIW, I've successfully used this sodium silicate, https://psh.ca/collections/sodium-silicate/products/sodium-silicate-n-water-glass. It's a 3.22 SiO2:Na2O ratio, which isn't considered optimal for foundry sand. My first attempt with it was at a 5% by weight sand/silicate ratio, that attempt was unsuccessful, I upped the ratio to 6% and that produced a usable core. This is one of the cores I made using this silicate.
