Good news for us quilters or embroiderers ! Prym just launched a new pencil for marking fabrics with lines thinner than a millimeter, and yet very perceptible. It is in fact a cartridge pencil, with an integrated eraser for the little corrections, while the lines disappear completely with water. It is writing really fine, and comes in black, white, yellow or pink; so it is useful on any fabric. The pencil is coming with white cartridges, while the other colours can be bought as separate fillings.
I wrote with the white one on the samples here below, and, believe me, I'm already addicted because it went really easy!!! I love it when manufacturers give us such wonderful material to simplify our creative moments.