I have tried this out and it works well (note from Joel)

From Semperfli:

This wax has been specially formulated to use with Nano Silk and EVERY GSP thread in the market. Some waxes are too harsh for the fine but extremely strong fibres of GSP threads. Semperfli GSP Wax will glide across your GSP threads and colour them black and create a tacky, waxed surface for you to add dubbing, to tie on or tie off your GSP threads