When I did redwork , bluework, or blackwork embroidery, I used the Sakura Pigma Micron pens 01 size using the color to match the thread I was going to use, red, blue, black. These pens mark with an extremely fine line and are acid free and archival safe. So washing out was not an issue with me. The lines also stay on and do not rub off while you are working.
Love the kit and if I was still able to do hand embroidery, would jump on that one.
here is a google search showing where the pens are available.......
https://www.google.com/search?source...31.-n-k-YWLK-E