Rubber Problem

Hello, I got a new bat around 3 months ago, I use red to my Forehand. I just recently discovered the bottom centre part of the rubber has a black shadow almost like a smudge, I figured it was caused by playing red to your Forehand and holding your thumb on the centre-bottom part of your bat, is there any solution? As in a way to restore the rubber to its natural colour?    

 I Use:
FH: Butterfly Sriver L 2.2mm
BH: Butterfly Sriver EL 2.1mm

Any help would be appreciated.                                                                                                                       Regards, Harry

Hi Harry,

Yes I have seen this as well on some rubbers.  I haven't found a solution.  I am sure our readers will be able to help.