Yes, in theory.
You can add a small amount of titanium oxide powder (which you should be able to get from your local hardware store) to your mix.
Please note the following
- ST100 base colour is grey, which would be the starting point, so generally making it darker with some colourant is possible (some of our customers add some black to make it darker)
- Pipe Repair (ST182) is a slightly lighter grey when setting, so that would be the starting point for colourising.