This ought to be such a piece of cake, that vendors should flock to you with offers to do this. However, if they do not, Florescene dye should do the job quite nicely. As a matter of fact, contact any major dye distributor, and describe the problem, and they will likely be able to give you many possibles. It may be as simple as going to the yellow pages, and looking up dyes, or chemicals. If I can help, call, fax, e-mail Rudy Sedlak RD Chemical Co Mt View CA fax 415-962-0370