Sodium silicate recipe: The good stuff

I was able to successfully remelt the solid lumps of sodium silicate back into solution with moderate heating well below boiling point. I tried filtering with a cotton cloth which does work for a short while to yield a clear liquid but the cloth clogged and even seemed to harden a bit. Some fine woven cloth was then used to remove any solids, the rest of the cloudiness will have to settle and get poured off. It has about 20% extra water to make it less saturated and try and prevent it crystallizing again.

 

Do you think it could be bentonite ? Ie. The wrong kind of foundry kitty litter...

Jeff

 

That looks like the bentonite kitty litter and not the silica gel kind which are translucent clear-white crystals like fine gravel in appearance. The last batch I made has also had the milky, silt-like material settle out and is now a clear liquid like the commercial sodium silicate. The stuff I bought was described as "irregular silica gel crystals". I've made two batches, one with milky crystals and one with clear crystals and the clear crystals makes a clearer sodium silicate, much less cloudy.

 

That's the stuff, good luck!.

 

I have had good success using both purchase SS and catalyst, the catalyst is expensive and I have only found it in 5 gallon buckets for about 180.00, you only use about 8 ounces in a 200 lb sand mold.

When I make my own SS I use distilled water , it makes a big difference over tap water. I add the caustic soda powder into the water and let it go into solution with a little stirring with a paint stir on my drill, it provides its own heat, i have found that the right amount of water is about 150% to the soda by volume, I then add water until the soda goes into solution, I then add the cat litter silicon beads until no more will disesolve about 250% in relation to the soda. what won't dissolve is then skimmed off. I then add 30% more water and stir. This appears to pretty well stop the crystals from reforming. It has been successfully used with the commercial catalyst or Co2. I have been trying to find out what how to make a catalyst because the catalyst gives a more even reaction with out using the Co2.

I use a small cement mixer with the vanes removed and 4 or 5 large rocks to mix every thing together as a Mueller?? it gets everything coated and provides for a consistent hardening. I have used as fine a sand as 120 gr. it takes more SS then the coarser sand does but it provides high detail. I also re-use the sand by putting it into the cement mixer breaking it up and using about a 75% of the normal SS mix. I normally only cast aluminum so the combustible in the sand used for bronze, brass, or iron isn't necessary due to the lower pour temp.. I would probably use flour as the combustible from what I have read.

Art B

 

I'll save you the search. https://shop.clay-planet.com/chembond-catalyst-210.aspx

 

thanks David,Rocco

that catalyst is the really slow catalyst 75 to 85 minutes, it is the same one that I originally used, what I am trying to do is get the faster catalyst like the Chem Bond 240- 20 to 25 minute I never thought about buying a 5 gallon bucket and selling it by the quart or pint. I may end up doing that and getting back the money on it. The SS they are selling for $195.00 for 5 gallons I can buy for $50.00 My business has been providing lmaterials to the hobby market and this kind of fits in that.

Art B

 

The silicate worked great? The silicate+catalyst worked great?

This will be for casting AL?

I ask as, used for iron, the core will turn to rock if not weakened with sugar.

Denis

 

I've CO2 cured silicate cores with aluminum and had no trouble at all removing the cores, I guess it's the extreme heat of cast iron that causes the problems.