I've only done full pads at the moment, I did do a test piece by pouring some polymer into a mould sat on top of a old pad that had been cleaned up. It didn't seem to have much hold after it had set.
If recapping pads, the old pad needs to be cleaned up really well, then a special primer needs to be applied to the surface before pouring the polymer. I've got some on order from the USA,, cannot find anything similar in this country but I'm sure there will be somewhere.
I need to recap some pads and test them properly before making too many and finding there no good. Making a new pad is a lot better, but a recapped pad is a lot cheaper to make.
Im using a PMC-790 industrial liquid rubber compound .
Spray a wax based release agent in the mould and leave to dry, mix the part a and part b polymers together making sure they are above 23c, also the mould needs to be warm, once poured the polymer will start to set within 5 mins. I have a hot box for food, bought off eBay for £40, can be kept at a constant 50c for 24 hrs, will hold about 12 mounds.
Will post pics of the mounds tomorrow, easy to make, made another 2 in about 30mins the other day, I now have 10.
Cvrt pads will be very difficult to do, I've some need doing but will give it a miss!