The extract of Irish Moss, called carrageenan, is often used in food products as a thickening agent. In paper marbling, carrageenan is blended with water to thicken the marbling bath, allowing the colors to float on the surface. In essence, it is the foundation of marbled paper.  

Carrageenan is easy to prepare and requires no boiling or straining. Simply add 2 level tablespoons of carrageenan per gallon of water and blend for one minute. Let the mixture sit for at least 4 hours to let the air bubbles rise to the surface (ideally 8-24). One pound will make approximately 27 gallons of size. Shelf life (of dry powder) is about 4 years if kept tightly sealed. Available in ½ lb, 1 lb, and 5 lb bags.