Was gonna suggest Birchwood Casey Gun Scrubber as it is safe to use on most plastics used in guns. Tried it on some carpet fibers I had on hand and they didn't dissolve. Most likely it WOULD remove Prussian Blue... but if nail polish remover worked, then it worked. Zippo lighter fluid removes most inks and oil-based paints as well, dunno how it would work on carpeting though.Wife tried nail polish remover (I think it is acetone based??). It worked fine.