In this case I bought the Posca White fine tip not for art primarily but to mark leather which had to be stitched. I was painting a line on the reverse 'suede' side of the leather to perforate and stitch along. This was a BIG ASK for the pen as the back of leather does not take paint very well at all. At times it was hard to get it to flow and mark effectively but with re-shaking and persistence I got it across the line in the end. Full marks to a product which has performed above and beyond the call of duty!