Well, The FBI were fingerprinting me so I could be a regulatory enforcement officer at the bank....nothing dodgy! Bigmamma, They took my fingerprints by making me touch a pad of very thick, sticky black ink before pressing my hand on paper. So you definitely need the thickest mix you can get. Their stuff was oil based. Maybe touching an ink pad for rubber stamps would work? I used to have Reynauds syndrome when I was young and sometimes had what you could possibly describe as "crazy red polka dots" on hands, arms or legs during attacks when the blood flow was interrupted. If you can post a photo, I'll see if it looks like the same thing.