I decided on the Stiga Syncro BTG water based glue - it was described as being easy to remove but still providing excellent bonding. It was also available in a larger 150ml bottle which would be convenient for me, seeing as I do a fair bit of rubber gluing, what with changing my own rubbers fairly frequently, and testing the occasional new rubber as well. As it turned out, this glue does quite a decent job, although my first attempt at using the glue was pretty disastrous. I have since worked out what went wrong (and yes, it was me, not the glue) and I am now using this glue without any more problems.
InstructionsUsing Syncro BTG is pretty much the same as for other water based glues - put an even layer on the sponge and blade, wait for the white glue to turn transparent (this is supposed to take 4-8 minutes), then attach the two together, and clamp for a little while to get a good bonding. Simple, you would think - and it is, unless something goes wrong, as it did for me!
First ImpressionsI had a rubber that I needed to reattach (it was coming off all around the edge of the blade), and I had used the rubber on a couple of different blades (using the last of my partner's speed glue to attach it - don't worry, for testing purposes only!), so there was already a thin layer of glue on the sponge. In hindsight, this was my first mistake - I should have taken the time to remove the layer of glue on the sponge. In my defense, I've never really bothered to do so in the past, and it never seemed to make much difference with the old style glues, so I didn't realize that water based glues would be different. My use of water based glues has really been just to attach new rubbers onto blades, not to reattach rubbers, so I'd never really used water based glue on top of the old style glue.
This proved to be a bit of a disaster, as it was very difficult to get even coverage of the glue over the sponge, and the water based glue took forever to dry as well. I had to keep spreading it out with my fingers to try to even out the coverage. Fifteeen minutes later and it was more or less ready.
While that was happening, I had also spread a layer of glue on the blade. If anything, this was worse. As soon as the glue hit the blade, it shifted into little pools of liquid, like water droplets on a window, refusing to stay spread out. What the heck was going on? Again, I spent plenty of time spreading the liquid around with my fingers, trying to get an even coverage. This also took much longer than 8 minutes to dry, because it kept reverting back into little clumps of glue. So I was basically going back and forth between the sponge and rubber, cursing to myself and feverishly trying to smooth out the glue.
Eventually, the glue dried enough so that I could put the sponge and rubber together, so I clamped it and left it overnight, figuring that by the next morning all should be well. And it was fine until the second day or so of using the rubber, when I realized that the sponge was coming away from the blade - of all places, in the middle of the bat! Plus the edges were starting to lift up a bit as well. Yikes!
TroubleshootingI thought about this for a while, trying to work out what might have gone wrong. It was easy enough to guess that I should have removed the thin layer of glue on the sponge of the rubber to begin with, but I needed to think a bit harder about what went wrong with the blade. Finally I remembered that I had sealed this particular blade with a thin layer of polyurethane, while my other two Timo Boll Spirit blades were sealed with sanding sealer. Aha! It must be the polyurethane making the glue clump up into little pools. Five minutes work with some sandpaper to remove the polyurethane layer, and my second attempt to spread the glue on the blade went much better - it spread out as normal, and dried much faster. Phew! So if you have sealed your blade with polyurethane, watch out when using water based glue - you may need to sand the layer of polyurethane back.
I also spent some time removing the layers of glue from the sponge, bringing it back to its original condition. Without the layer of glue, the Syncro BTG spread out quite easily and dried quickly, although I did have to keep moving the rubber around since the curve of the rubber makes the glue run down the slope, and pool in the middle. An extra set of hands to hold the rubber down flat would make this easier, but within 5 minutes or so the glue had dried with good coverage this time. So if you are using rubbers that tend to be curved when coming out of the package, I'd suggest a few paperweights that you can use to hold the rubber flat, although you'll probably still need to use your fingers to help out as well.
Success!This time, confident of success, I only clamped the rubber and blade together for half an hour. This seemed to work just fine, and I didn't have any further problems with the rubber lifting off.
Since then, I've used the Syncro BTG to glue on a number of new rubbers onto my blades. I didn't have any trouble with the sponge of new rubbers, and the blades that I sealed with sanding sealer seemed to work just fine with the glue. So overall this glue works OK, and the problems were really my own fault, part carelessness and part bad luck. Which is just as well, seeing as I've still got tons of it left!