Additives to Moulding Sands:

Additives are mixed throughout sand preparation according to the needs of molten metal and base sand to get specific characteristics in the sand. It helps in improving certain property of the base sand as metal penetration property, high temperature plasticity, surface finish etc. The usually used additives are given below.

Iron Oxide

It is utilized for both core making and moulding sand to develop high temperature plasticity and deep metal penetration and hot strength. In core sand it prevents cracking of cores. Superior quality iron oxide must have iron oxide content not less than 93% and iron content not less than 65%.

Molasses

This is commonly utilized in moulding of iron castings. This is obtained as a by-product during sugar refining. This is added to achieve high dry strength and collapsibility. It also increases green strength. But, because of the high hygroscopicity of the mix prepared along molasses, its utilization is not much favoured for good quality casting.