Silicon is well known for its chemical inertness, (i.e. it tends not to react with many other chemicals). Depending on what type of silicon you are dealing with, this may or may not be easy to solve. If the silicon is from a lubricant, it is probably the graphitic form, which is soluble in a strong combination of nitric, and hydrofluoric acids, neither of which I would recommend for you to use...nor hydrofluoric acid is not easy to come by. If it is silicon from an acidic form (probably any other form other than a lubricant), you should try ammonia. In either case, leave your acetone at home...it will NEVER work! UPDATE: An ammonia solution worked very well in this case   _{Your Comment}