TECHNOLOGY FOCUS - POLYMERS - Preferred Components: The alkyl substituents of the lower MW phenylalkylsiloxane have from 1 to 6 carbon atoms (preferably methyl groups). The lower MW phenylalkylsiloxane has an average MW of 200-1000 (preferably 400-800, especially 600-700, particularly 650-750). The lower MW phenylalkylsiloxane is linear (preferably -OH terminated). The alkali is selected from alkali metal compounds (preferably alkali metal hydroxides, especially potassium hydroxide). The sealant composition comprises plasticizer selected from mineral oil, phthalate or lower MW polysiloxane; an inorganic filler selected from calcium carbonate, silica, aluminum oxide, mica or kaolin. The crosslinker comprises alkyltrialkoxysilane or a disilaalkane. The adhesion promoter comprises ethylenediaminepropyltrimethoxysilane. The catalyst comprises a tin, titanium, aluminum, zirconium, or bismuth compound. Preferred Process: The method proceeds initially under vacuum and prior to stopping the polymerization is conducted for a period at around atmospheric pressure. The polymerization reaction is stopped using a neutralizing agent. The neutralizing agent comprises acetic acid or a silylphosphate. EXAMPLE - Polymerization (test) of lower molecular weight (MW) phenylmethylsiloxane in the absence of dimethylsiloxane fluid using potassium hydroxide catalyst was conducted as follows: OH-Terminated phenylmethylsiloxane (average MW 560) (1 kg) was loaded into mixer and heated up to 90 degrees C and degassed. KOH (1N) (6 g) was added and a vacuum applied, 30 minutes later the viscosity was increased rapidly and high bubbling was occurred. 10 minutes later the alkali catalyst was neutralized with of acetic acid (1N) (6 g). The viscosity measured at 23 degrees C was 100000 cP (mPa.s), and the molecular weight was 30000. Similarly a comparative polymerization of lower MW phenylmethylsiloxane using dodecylbenzylsulfonic acid (DBSA) catalyst was conducted where no increase in the viscosity was observed over time.