containing 0 1 by weight of sulfuric acid is added dropwise thereto with stirring reaction is continued for another 3 hours at this temperature the reacted product is then heated to 180 u00b0 c while the distillate ethanol and unreacted silane produced is distilled away through a distillation column thus in an actual instance an alkoxy group containing organopolysiloxane was obtained in a yield of 1 198 g which had a viscosity of 128 centistokes at 25 u00b0 c a content of ethoxy groups of 30 2 and a refractive index of 1 442 the resulting product is an organopolysiloxane represented by the following average compositional formula the compositions containing the components shown in table 1 were provided with a brush on the surfaces of beer bottles parts of which were whitened by scuffs the coating being controlled to form coat films of about 3 u03bcm thickness the coated bottles were allowed to stand for 3 days at room temperature to cure the coat films the properties of the resulting films were measured whereupon the results shown in table 1 were obtained various scuff masking agents were provided on the surfaces of beer bottles parts of which were whitened by scuffs the properties of the resulting films were measured whereupon the results shown in table 2 were obtained the properties of the coat films were measured in the following manner the coated sample was immersed in water at 25 u00b0 c and the immersion time until a part of the coat film was removed was determined the sample was judged to be 34 good 34 when the immersion time was one week or longer and judged to be 34 poor 34 when the immersion time was shorter than one week this was measured by a cross cut pressure sensitive cellophane.