A process for preparing a composition comprising the step of selecting a composition for preparing a moldable, test plaque having (1) a MDR ts1 at 150 degrees Celsius of at least about 20, (2) a MDR ts1 at 140 degrees Celsius of at least about 50, (3) a retention of tensile strength of at least about 75% after two weeks of aging at 150 degrees Celsius, (4) a retention of elongation of at least about 75% after two weeks of aging at 150 degrees Celsius, (5) water tree resistance less than about 45%, and (6) sweatout of less than about 100 ppm of the thiobis phenolic antioxidant and (b) imparting water tree resistance to the insulation of cables, the composition comprising (i) polyethylene, and based on 100 parts by weight of component (i), (ii) about 0.3 to about 0.6 part by weight of a thiobis phenolic antioxidant selected from the group consisting of 4,4′-thiobis(2-methyl-6-t-butylphenol); 4,4′-thiobis(2-t-butyl-5-methylphenol); 2,2′-thiobis(6-t-butyl-4-methylphenol); or a mixture of said compounds; and (iv) about 0.4 to about 1 part by weight of a polyethylene glycol having a molecular weight in the range of about 1000 to about 100,000.