Some random patent info I had on a file when I was researching sodium silicate years ago. Don't know if any applies. I went with epoxy binder instead so I never got around to testing any of these chemicals. --- "The Water glass casting technology is from Russia. Now it is one of the most common investments casting processes in China. About 75% of foundries focus their business on water glass casting. the rest are silica sol casting factories" -- "Sodium silicate react with ammonium chloride and water to produce orthosilicic acid, sodium chloride and ammonia. " "Ammonia is un-ionized, and has the formula NH3. Ammonium is ionized, and has the formula NH4+ "...placed in a bath water mixed with a ammonium chloride solution." ...transition zone hardening bath is 24% ammonium chloride solution, the transition zone firm time is 30 min, dry 100 min after the transition zone sclerosis; -- Alternative hardening agent (no ammonia fumes) Reaction pool: water: 70 ~ 80 parts Sodium chloride powder : 15 ~ 25 parts, allow sodium chloride fully dissolve... ...calcium carbonate: 5 ~ 12 parts, calcium carbonate is slightly soluble in water, stirs and forms turbid solution; ...hydrochloric acid "concentration 36 parts and water" : 1 ~ 3 part, in turbid solution, slowly inject the hydrochloric acid of 1 ~ 3 part again, and fully stir; ...finally casting shell molds is put in sclerosis pond for 3-5 minute, remove, drain, allow to dry.
His funnel is much like the top half of my furnace.. Chem bond would have been handy to use when it was made.... The fumed silica seems like a good idea and held up under a small iron pour.. After 2 days the co2 in the air hardened my lid.... My success with it led me to do the wax skulls with 2 coats of dry wall mud, and a layer of SS and fiber blanket.. Got every thing laid out to start again, the mold is outside warming to day time ambient temp..
