for conventional rubber to metal adhesion promoters such as cobalt materials which are conventionally used in wire coat stocks to attain and maintain needed rubber to wire adhesion properties in fact wire coat stocks that contain lignin provide more that adequate rubber to metal adhesion characteristics for typical applications such as in tires and maintain needed levels of adhesion over long periods of product service for instance high levels of rubber to metal adhesion are maintained under harsh conditions such as exposure to elevated temperatures and high levels of humidity the utilization of lignin in wire coat stock formulations in accordance with this invention is also economically advantageous since lignin is a low cost alternative to most conventional adhesion promoting agents lignin is also environmentally friendly and does not present any known health hazards lignin is derived from wood and constitutes about 25 percent to 33 percent of the dry mass of wood accordingly lignin is an abundant naturally occurring organic polymer which is a renewable resource since it is derived from trees accordingly lignin represents a low cost abundant environmentally friendly and highly effective alternative to conventional rubber to metal adhesion promoters the present invention more specifically discloses a wire coat stock composition which is comprised of a rubbery polymer about 40 phr to about 80 phr of carbon black and about 2 phr to about 30 phr of lignin application_number US 89220410 A description the materials to which this invention is directed rubbers reinforced with metals are within the general class of materials known as composites a composite is a complex material containing two or more distinct and structurally complimentary substances in this case rubber and metal.