rtv silicones are classified as either one or two part systems the one part systems require no mixing by the end user and rely upon moisture vapor from the air to achieve an end cure one part rtv silicones are preferred for the coating composition used in the roofing system herein described the one part rtv silicones are commonly classified according to the byproduct which is evolved during the cure the four most common byproducts are acidic acid oxime alcohol and acetamide two component rtv silicone systems include a polymer and a catalyst moisture is not required to cure a two part rtv system the two component systems are commonly classified as either condensation or addition based upon the reaction mechanism of the catalyst a one part acidic rtv silicone is the preferred material for use in the roofing system of the present invention 50 by weight 99 pure sio 2 s g 2 5 2 8 pigmentas desired for coloring is added to the total composition usually in a quantity of 1 2 by weight of the total the solid silicone is dissolved in the naphtha with proper mixing and sio 2 and pigment are added gradually while continuing to mix it is to be understood that the term silicone rubber 34 solution 34 as used herein is intended to encompass 34 suspensions 34 where some of the silicone along with the sio 2 is not actually in solution in the true sense of the word while the silicone rubber solutions herein described may be applied by brushing doctor blade or other conventional means spraying is the preferred application technique referring now to fig3 of the drawing a typical substrate for application of.