People have also (me included) used Rit fabric dye available in super markets. It's also water based etc. and easily available. I used some reciently on a Greenlan paddle. I was able to control the line/edge by not having one. I sprayed with an airbrush and did a fade. I usually don't use stain or dye and wanted to cover some black paddling glove rubbings on a natural oiled paddle.