For the first time, polyols derived only from castor oil can be used to produce tough coatings, flexible adhesives, soft sealants and elastomers. The Polycin GR Series is the latest polyol line from Vertellus Performance Materials Inc. (Indianapolis, Ind.; edlinks.chemengonline.com/6519-543). Polycin GR polyols have a hydroxyl number from 340 down to 35 with functionality from 2.9 to 2, which means polyurethanes made from the “natural” polyols have a hardness from 75 Shore D (equivalent to a hard hat) to 10 Shore A (softer than a rubber band) and tensile strengths from more than 6,000 to below 50 psi. The ricinoleic (C18) backbone contained in the GR Series yields a finish that is insensitive to moisture, absorbing six times less water than that absorbed by comparable polyether polyols, says the company.