FORMVAR(R);FORMVAR(R)15/95E;Vinylacetalpolymers,formal;FORMVAR(R) SOLUTION, FOR MICROSCOPY,0.25 % IN ETHYLENE C;FORMVAR(R) SOLUTION, FOR MICROSCOPY,1% I N ETHYLENE CHL.;FORMVAR(R) SOLUTION, FOR MICROSCOPY,0.5% IN ETHYLENE CH;FORMVAR 15/95E;Polyvinyl formal resins