US Patent 9410059 Wax treated article and method of making

Water swellable articles are treated with wax by applying a molten wax to the article, the wax having a kinematic viscosity of between about 0.1 cSt to 20 cSt at 100° C., wherein the temperature of the article at the time of applying is about 40° C. to 200° C., with the proviso that the temperature is not less than 30° C. below the melting point of the wax. Using this method of treatment, swelling of the article in water is reduced by at least 25% compared to the same article treated with molten wax wherein the article is at ambient temperature at the time the wax is applied.