Effulgence-515 polymerization inhibitor is used to increase the shelf life of olefinic resins. It is a yellow to brown solution of an inhibitor in a monomer, and tends to darken with age. Because it is typically used at low concentrations in formulated systems, this discoloration does not affect performance and should not affect the final product quality. Effulgence-515 polymerization inhibitor may be used in coatings, adhesives, photoresist, printing inks and printing plates as well as unsaturated polyester resins, vinyl monomers and acrylated oligomers. It typically is used in concentrations ranging from 0.1% to 1% by weight.