I'm looking for a rubber press pad/slab in order to apply uniform pressure in a pneumatic wakeboard press where "3d top" surface composite wakeboard are pressed. We press @ 50psi, 70C and 3D relief is about 1/4" deep. What type, thikness and hardness of rubber will work for this purpose? The rubber must be soft enough to fit the 3D surface and hard enough to push out excess resin. Any idea? thanks     

A rubber pad will not apply uniform pressure. An air-filled bladder will.

Thank you for your reply Compositepro. We already use an air-filled bladder to apply pressure in our setup but the bladder do not push directly on the board (our bladder will not support 70C and the composite must be heated from both the bottom and the top). In fact, we are looking for a pad (silicone or neoprene?) to compensate for the little relief of the top side of the boards. The pad must rebond for multiple application. Another possiblity is to make a female mold (urethane shore 80-100A) but accurate positioning will be a challenge.
here is a detail of our setup (from bottom to top):
-Bottom mold
-heating element (silicone blanket)
-alu plate
-wakeboard
-Pad? female mold urethane? 1/2" thick
-alu plate
-heating element (silicone blanket)
-insulation
-bladder
-top mold