Have a peak at this....
These Pilot pens are actually meant for paper, but can be erased with friction - you use the grey tip at the end of the pen to erase it from paper.
I used the to write on fabric...
And then went over the text with a steam iron.... ONCE
I only went over the middle, I didn't go over the part that is still visible
The pink line is on my ironing board cover... the only trace of the pen is if you hold it up at just the right angle in just the right light, you can see what you wrote - much like you would be able to see an imprint of what you wrote on the sheet of paper under the one you wrote on. It is for all intent & purpose GONE!
This will be perfect for marking darts etc!