Yeah, plain old Sharpies don't last long in high moister area, esp when rooting... I marked all the cuttings I got form Jon with black sharpie, then happily mixed them together in the same rooting bin. 2 weeks later, I could only still read about 2 out of 13. I was only able to sort them out because I know I only had 5 varieties, how many of each I had and able to make partial identifications of some of the names and deduce the rest.
I definitely need to get one of the acrylic pens above. Thanks!