[Bruce]

Thanks all for this wealth of suggestions.....I've both spirit based dye and standard gloss black enamel in the workshop so will have a play with both.......dye for resin sounds interesting too and last time I looked these dyes were available in quite small bottles. I still have a small bottle of orange resin dye (fibreglass kayak repairs) that I've been using for something like 40 years and many many often quite substantial repairs - it goes a very long way.

I'll report back when the job is complete......

Bruce