Used a Zymol product for years for rubber parts. But unfortunately the company has dropped the product though it continues to make available a similar one that likely produces similar affects. Current product is Zymöl Treat. Kind of expensive but you don't need much and if its like the other product it has worked well for me. For small stuff I clean the rubber, work some into the surface leaving a light coat, then place it in a plastic bag, burp it and leave it. Ever week or so I rub the product around on the surface through the plastic bag until it's where I like it. Have also applied and wrapped original tires with the stuff them cling wrapped the tire and left it in storage to try and block our ozone and hopefully restore the rubber a bit.
Agreed you would be best served just to make another from fresh new material
As for board measurements. Measured one out in the garage (so no note of where or when its from ) Measured out at 16" x 12"
