Hello again; The only reason Tony's sundial discolored is because he covered it with plastic while the silicon was drying. If silicon is used as I mentioned in my last message, with good air circulation, then there is no discoloring of the visible brass since all the silicon is underneath the brass.
By the way, after you apply the silicon and place the brass in its cavity, you can press the brass down so that it is flush and level with the surface of the stone. This causes excess gooey silicon to squeeze up around the edges. (If you use masking tape on the stone you can prevent the excess silicon from getting on the stone) This excess wet silicon should be immediately removed using a spatula. The remaining unwanted silicon residue should then be completely removed using a rag and paint thinner. Let dry eight hours. John Carmichael Tucson Arizona> > >"Is it ammonia that silicone gives off when it is curing?" > >There are many types of silicones and each has its own curing by-products: > >Many one part types give off acetic acid (Highly corrosive to sensitive >metals like copper). Some types give off both alcohol and ammonia! which it >sounds like you used. These are not as corrosive but will discolor copper >based metals. It is best to search out the non-corrosive, pure alcohol >byproduct types if you must avoid these consequences. Some of these >specific GE products are: RTV 6700, 5810 and 6800. Most all one part types >require moisture (humidity) to cure, which is great in England but may be >quite slow in Arizona/New Mexico! > >For hi-tech applications we use 2 part types, which can cure deep sections >in a closed environment, give off only a little alcohol, and are completely >non-corrosive. They, however, are not practical for general use as they >require many hi tech steps for proper mixing, curing and adhesion. > >Good luck with these magical silicones but beware of the after affects! >Especially on brass and plastics. Check with your local industrial supply >house for details. > >
