Sewing thread is almost impossible to dye. This is because the temperatures to paint this thread are so high that you need a machine for that. Although I understand some conductive thread is made out of a combination of cotton and steel. This might be more doable, but I haven’t been able to get any of this..
I did find a way to paint little bits of thread. The result is a bit messy, but it works! It cannot be used in a sewing machine though.. Maybe later in the process i find a method that does make it possible to dye sewing thread at lower temperatures..
In this experiment I used the general conductive sewing thread, with textile paint. This is textile paint that is used to paint on textile, so not to wash & dye! When ready, the paint is fixated by ironing it.
I will try order conductive cotton thread, maybe I’m able to dye it with normal textile paint.
Kobakant’s article about dyeing conductive sewing thread (using heating chambre): https://www.kobakant.at/DIY/?p=4123