What about ordinary nail varnish?  Coloured to suit your sheep!
Cathy

At 8:44 AM +1000 2/8/01, Dalefield, Rosalind wrote:
>Can anyone suggest something that will permanently stain keratin?
>
>This is actually for keratin in the living animal; I want to mark the (light
>colored) hooves of Merino sheep so I can track rate of hoof growth. But I
>figured Histonetters would have some good ideas...what stains just won't
>come off your fingernails!?
>
>Thanks in advance,
>
>
>Rosalind Dalefield BVSc PhD DABVT DABT
>Senior Research Scientist, Toxicology
>Plant Toxins Unit
>CSIRO
>5 Portarlington Rd
>Private Bag 24
>Geelong
>VIC 3220
>Australia
>
>Phone 61 3 5227 5730
>Fax     61 3 5227 55