Response by: JP, December 23rd 2014 2:32:39 pm
In case this thread might help someone else...
Is it possible the surface of the latex has something on it that's preventing the glue from adhering properly? Contaminants could be release compounds from manufacturing of the sheet, any sort of polish or shine, oil from your fingers, anything other than a fresh, bare rubber surface.
This is often an issue when patching something that's been worn, you really need to get the surface clean. Industrially, tire shops use a "liquid buffer" for that sort of cleaning.
Sometimes, the surface simply isn't gluable, for example, if it's been chlorinated. Then you need to physically buff the surface with very fine sandpaper to expose gluable latex. Otherwise, even the best cements won't chemically bond, and will peel when stretched.