CO2 – Sodium silicate core:
Here Silica sand, which is prepared in a separate mixer using sand, and Sodium Silicate is added 5 to 6 % of sand quantity 100 kg, with a Dry core break down agent added in it.

While sand and break down agent are mixed first then Sodium Silicate in added and mixed for 2 minutes or so ensuring proper mixing.

Than CO2 gas is passed through the holes made in pattern or cores. And gas is passed at a uniform pressure tight, the sand mould is hardened. And then core is stripped out of the pattern by ramming smoothly.