Fibrous Materials:

Utilized to prevent scabbing, develop collapsibility, and expansion defects. The commonly utilized materials are straw, asbestos, wood flour, dried glass , sawdust and manure.

Dextrin:

This is a binder that increases air setting strength, collapsibility and toughness and prevents sand from rapidly drying. Throughout pouring it gasifies generating voids among sand grains and allowing their expansion without distortion. Commonly Dextrin is utilized with core sand to enhance dry strength and like a binder for mould and core washes.

Sulphite Lye:

This is a by-product of cellulose industry and is utilized for imparting better, hot strength, dry strength and collapsibility to moulds. Its utilization is more favoured in the production of big and heavy iron castings.