Colour of PVC and how it effects everything else

[Alggys]

I'm going in circles on how much the colour of the material used in a record is related to its properties.
In particular the stitching, the only times I'm getting it is when I use black PVC, there was never stitching on any coloured record that I've made(splatters, marbles, solid colours).

Additionally can stitching occur from a bad batch of PVC, as doing all of the recommended changes to the cycle and press does not help?

Cheers,

[trendkiller]

Stitching is usually either from pvc being too cold or a physical movement of the record during pressing (i.e.-the disc arm moving when the press closes). Check those out.