To a 164 gram sample of the formulation of Example 1 there was added 3 grams of the silicone cluster compound M<OSiR{OSi(OR')3 }2 >a, wherein R is a methyl group, R' is a secondary butyl group, a is 2 and M is --CH2 C(CH3)2 CH2 --, with mixing prior to curing with 1% by weight of benzoyl peroxide for fifteen minutes at 70??? C. followed by five minutes at 150??? C. In the adhesion test on aluminum