Natural Rubber (NR) is produced from the crop harvested from rubber plantations both in the latex form as well as in the field coagulam form. Latex is a milky white dispersion of rubber in water and field coagulam is the auto coagulated latex on the tapping panel (tree lace) and the collection cups (shell scrap and cuplumps). Both the latex and field coagulam harvested from rubber plantations being highly susceptable to degradation by contamination on keeping, have to be processed into marketable forms that will allow safe storage and marketing.

The most important forms in which NR is processed and marketed are the following:
 
• Sheets
• Crepes
• Block rubber, technically specified
• Preserved latex concentrates
 
Among these 4 forms/types, the first three are in the dry form and almost 90% of the total NR produced in the world are at present marketed in these 3 forms. In the international market, these 3 broad types of dry NR, are available as over 40 grades consisting of ribbed smoked sheets and air dried sheets, crepes, which includes latex based and field coagulam derived estate brown crepes, remilled crepes etc. and Technically Specified Rubber in block form. In addition, there are a small number of speciality natural rubbers including chemically modified products and blends/composites.

Among the 3 types, crepes are now of minor significance in the world market, probably less than 75,000 tonnes per year since field coagulam grade block rubbers have virtually replaced brown crepes excepting in India and only SriLanka and India continues to produce latex crepes. This would mean that sheet rubber and block rubber are the dominant types of dry NR available in the world market and this dominance reduced the number of grades used in any volume to the 10-15 within these types. However, an attempt is made to give the details of each type of NR with the grade descriptor both for the benefit of producers, marketers and consumers of NR in India as well as in the world.