Abstract: An ultrahigh molecular weight polymer, such as ultrahigh molecular weight polyisobutylene, is used as an additive to enhance the coating properties of a solvent. The polyisobutylene has a molecular weight of at least 2.5-3.0 million daltons, preferably greater than about 6 daltons, and is provided in a preferred concentration of 0.05 to 0.3%. The solvent can be a medicinal grade mineral oil. Other suitable solvents include hydrocarbon oil and low viscosity, synthetic compositions. In all cases, the coating properties of the solvent are greatly enhanced by the addition of ultrahigh molecular weight polyisobutylene. In another aspect of the invention, ultrahigh molecular weight polyisobutylene is used as an additive to enhance the viscoelasticity of a mineral oil based sunscreen formulation. In still another aspect of the invention, the fibers of a fabric material are coated with an ultrahigh molecular weight polymer to greatly strengthen the fabric.