uncleof6
Active member
Well, not quite accurate. There is a great deal of difference between the consumer grade sealants, and the industrial grade adhesives, that are being discussed. Also, RTV is an acronym for Room Temperature Vulcanizing, which has absoluting nothing to do with what a particular product would be used for. To conclude, a co-polymer of silicone and acrylic will NOT clean up with water; there is no such thing as acrylic silicone.
case 1: "You are talking about the same thing, silicone is an adhesive. adhesive silicone is 100% silicone and so is silicone. It doesn't matter how they market it."
A rather oblique, redundant, circular comment....marketing has nothing to do with this.
Silicone composition, varies greatly from product category to product category. Simply looking at the physical properties of a consumer grade sealants, and industrial grade adhesive silicones, shows this very plainly.
Of interest to this thread, is the adhesive strength of the material. While the adhesive strength of "sealants" is so low, it is not listed in product data sheets (not speaking of the MSDS,) with products suitable as "adhesives," the adhesive strength, though the weakest property of silicone—is far higher. Momentive RTV100 and SCS1200 are pretty much the ones with the highest adhesive strengths. (at or above 40 lbs/in) Silicone I has such a low adhesive strength, it is not published—as the product is not intended as an adhesive: not supposed to be used to hold stuff together and it does a poor job of it, by comparison to industrial grade adhesives. With aquariums, it makes the difference between a tank holding water, and the water all over your floor. This is a complex topic, but that is far as it need go for this thread. The bottom line is that not all silicones are suitable for our purposes.
case 2: "unless you mean acrylic silicone which is water cleanup so it would not work under water."
This is what would be referred to as "not 100% silicone." It is actualy a co-polymer of polysiloxanes and polyacrylates. Since the solubility of silicone is ambiguous, (though non-polar organic compounds are not water soluble, such as methane, ethane, etc.) suffice to say, you won't be cleaning up a co-polymer with water, more likely MEK or other organic solvent. However, a co-polymer silicone will not hold glass together worth a toot.
case 3: "I would not use RTV, it is for gasket making in engines."
Not true. Every compound that does not require HEAT to cure is room temperature vulcanizing. That includes every single polysiloxane on the market, that I can think of. They are all RTV. High Temp silicones are used for gaskets in engines, in some cases, however they are still room temperature vulcanizing; merely formulated for high temp use. They are not, however, recommended for aquarium use: the adhesive strength is lower by around 50% or more.
In the end, what seems like comparing apples and apples, is actually trying to compare apples and oranges.
