When I paint on fabric I use Delta Ceramcoat acrylic paint and use a brush to paint it on. Once it dries it is permanent. I am an artist and I get paint on my clothes sometimes and it won't come off! Using plane ink on fabric the ink will bleed. Using a medium is the same as using acrylic paint or using oil paint with a medium. Oils take time to dry for quite some time. Think about it artist canvas is painting on fabric when they paint.