HouRman9

Let me clarify that the glue is not exposed at all. Rubber cement is the glue that attaches the surface rubber to the wooden paddle so this glue does not come into contact with the ball. Speed gluing is simply RE-gluing your paddle every time you play so the fresh solvent fumes from the "wet" glue soak into the sponge and add 30% more speed and spin. Right now speed gluing is perfectly legal, though there is a "BAN" coming soon next year. Perhaps due to the toxic fumes from harmful glues people are using.

What makes the Loud Speed Glue "TOCK" noise? In table tennis there are ping pong rubbers that involve a thin 1-2mm membrane of closed cell foam (Like Neoprene). Well this foam is between the wood paddle (blade), and the rubber outer layer(topsheet). Well there's this practice called "Speed gluing", which involves applying fresh coat of rubber cement on the foam immediately before playing with the paddle. This is done to increase the spin and speed and is done by many professionals as well as by club level players. Chemicals in the glue are believed to be the cause and include solvents such as toulene, heptane, and trichloroethylene (The chemical found in REMA tip top vulcanizing fluid). These chemicals soak into the foam and increase elasticity, causing the foam to "expand". Chemical vapors appear to be temporarily soaked up by the tiny closed cells of the sponge after a fresh coat of glue. What happens when you hit a ball at a certain velocity with a glued rubber is there is a distinct LOUD "TOCK" noise that isn't normally there. Some people say the sound derives from the solvent vapors (under pressure) converting into a fluid state, back into a gaseous state, thus making this loud noise. I've also heard the term "Cavitation" being used in other online research i've conducted. After a day or so when the glue solvents have evaporated, the rubber loses the "speed glue effect", and the "TOCK" sound is gone. So far I have not found a complete description of what exactly is going on in regards to the "speed glue noise". I am hoping somebody with a good physics or chemistry background could perhaps enlighten me with an easy to understand explanation. Is it feasable for a gas-fluid-gas conversion to be taking place by hitting a ping pong ball, and would that make the "TOCK" noise? Thanks