What solution did u go with in the end and did it work?
Incidentally, I sprayed some lambs over a week ago using a can from the Net-tex goodie bag and another ritchey one that I already had.  The Ritchey spray mark was pretty much gone after a couple of days, the net-tex one is still going strong!!!!  Just a shame they sent me red and blue, I don't think blue will show up on black, but I might give it a whirl. 
 
 Thanks Net-Tex/Rumenco 
