Cashew nut shell liquid is a by-product of the cashew industry. The nut has a shell of about 1/8 inch thickness inside which is a soft honeycomb structure containing a dark reddish brown viscous liquid. It is called the cashew nut shell liquid, which is the pericarp fluid of the cashew nut. Cost Effective Modern Materials In the search for the cost effective modern materials, CNSL and its products have a significant role to play. Being renewable, it offers much advantage over synthetics. Its versatility stems from its innumerable applications in many areas.