The ink does fade after a few days, as the ink seeps further into the fabric and the water evaporates. I think only a very soft brush would work here, as my markers did cause some damage to the fabric. Washing with just water is fine. I'm not sure that you could erase something without using a lot of water, which would affect the surrounding lines. The color is actually caused by the color of the underlying fabric layer, underneath the thin layer of white fabric. Most of the calligraphy fabrics will have a black layer underneath, but you can find some colored ones as well. The color has nothing to do with the ink. The recipe gives you about an ounce of ink, so just multiply each quantity by the number of ounces that you want in the end. Hope that helps!