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