Tool Tip #1: Block Tenderizing

Did you ever rubberize a raw egg back in elementary school science by soaking it in vinegar?  Vinegar works well to rubberize rubber too.  So if you have some quarter-sheet sanding blocks with stiff upper lips that refuse to open enough to admit and latch the paper easily onto the nails, try this:  completely immerse the block(s) in fresh vinegar for ten days or so.  Unless the block is really more plastic than rubber it should emerge fresh and flexible as the day you bought it.  The bottom now might even flex to concave during paper installation, insuring a nice taut sanding surface.