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Foundry Sand CORE KIT, Sodium Silicate & 70 MESH Silica (10LB)

Foundry Sand CORE KIT, Sodium Silicate & 70 MESH Silica (10LB)

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This kit allows small scale production of cores used in sand casting metals. The kit contains both sand and foundry-grade sodium silicate binder. A CO2 source is required (but not included) in order to harden the sand. This CO2 source is ideally a high-pressure cylinder and regulator but can also be as simple as a small amount of baking soda and vinnegar mixed in a container.
Super-Silicate is non-toxic.
Steps for use are as follows: 1.Mix the super-silicate and 70 Mesh sand together at a ratio of approximately 4oz Super Silicate to 10lb sand. Mixing should be complete but not excessive (for small batches a metal spoon or even kitchen stand mixer can be used)
2. Put the mixture in a core box or other form of your choosing. Pack down mixture moderately to remove air spaces and voids (but not too tight as there typically must be room for the gasses evolved upon casting to exit).
3. Apply CO2 in the form of injection, bagging, or flow-through. For injection, a needle connected to a CO2 source is used to apply the CO2. Bagging uses a poly bag along with a CO2 source (we have even used a small amount of vinegar/baking soda). For flow through, CO2 gas is applied to one side of the mold and allowed to exit on the far side. Generally, bagging and flow-through give the best results due to more even gas distribution.
4. Assemble molds and pour metal. Always verify that sand cores are completely cured (not wet) prior to pouring molten metal.
Notes: It is possible to keep the mixed sand for a few days in an airtight container. Exposure to CO2 in the air is sufficient to harden the sand within a couple of days (depends on temperature and humidity)
Using excessive CO2 is not helpful. In fact it may make the cores brittle if severely overdone. Generally, using the smallest amount of CO2 necessary to harden the sand is preferred.