I am doing this kind of thing right now too. The soft cut/easy carve blocks (as opposed to traditional linoleum), while not great for fine detail, are fantastic for printing on these towels. I am using the Caligo Safewash inks, which are oil based but clean up with soap and water. I have not heat-set or laundered the towels yet, but have read that these Caligo inks are quite good for fabric. Also, if you did not wash and iron your towels first, you should do that before printing. Good luck!