Self amalgamating tape vs silicone tape comparison
Self Amalgamating tape is typically made from EPR rubber, EPDM rubber, butyl rubber or PIB (polyisobutylene). Silicone Tapes are made from a silicone elastomer, which although is referred to as "silicone rubber" contains no actual rubber. When "amalgamating" is used as a description to mean "uniting as one" then of course you could call either rubber or silicone tapes "amalgamating" tapes. But the industry term for amalgamating specifically refers to rubber amalgamating tapes, and not silicone tapes.
Rubber self amalgamating tape is usually heat resistant to 130C, while silicone tape is heat resistant to 260C. Silicone tape also has a greater resistance in cold; while rubber tapes become inflexible and even brittle at cold temperatures, silicone tape is flexible to -60C with a cold brittle point of -65C. Silicone tape also has a greater elasticity and greater elastic memory than rubber tape. Silicone tape also has a much higher tensile strength, typically 450PSI to 950PSI compared to the 150psi to 300PSI tensile strength of self amalgamating rubber tape. Silicone also has the advantage of being easier to color, so it is more common to find silicone tape offered in a wide variety of colors compared to only black and white rubber tapes. Finally, the most significant advantage of silicone tape is the fusibility, or the bond strength. The high quality brands of silicone tape fuse together in just minutes or seconds, while the lower quality silicone tape fuses in about 24 hours which matches the performance of rubber amalgamating tape.
So which should you use? Self amalgmating rubber tape or silicone tape? That depends on your application. For underground or automotive use, self amalgamating tape is ideal and cost effective, but is not as suitable for hose and pipe leak repair. Silicone tape, however, performs much better as a leak repair tape, with greater strength and fusion with the higher quality brands. Of course there is a difference in price between silicone and rubber tapes, and also a significant difference between brands as well. But overall, you pay for what you get.