Moisture:

Clay attains its bonding action just in the presence of the requisite amount of moisture. While water is added up to clay, it penetrates the mixture and makes a microfilm that coats the surface of each of flake. The molecules of water producing this film are not in the original fluid state however in a fixed and specific position. As more water is added up, the thickness of the film enhance up to a certain restriction after that the excess water remains in the fluid state. The thickness of this water film differs with the clay mineral. The bonding quality of clay based on the maximum thickness of water film it may maintain.

While in a mould sand is rammed, the sand grains are forced together. The clay coating on each grain behaves in such a way that it not just locks the grains in location but also makes them achieved that position. If the water added up is the exact quantity needed to create the film, the bonding action is best. If the water is in excess, strength is drop off and the mould be weakened. Therefore, moisture content is one of the most significant parameters influencing mould and core characteristics and as a result, the quality of the sand produced.