I have several boiled out and dried trophies, is it too late to bleach them or do they need to be bleached when still wet?
It's better to not let them dry out but you will still have some success. I had a Muntjac almost gold medal which had been left outside for the maggots rather than boiled and had gone quite brown. I then boiled it briefly and bleached it whilst still wet and it was perfect.
However, don't use bleach!!
You need Hydrogen Peroxide which you can get from hair stylist supplyers in a pretty strong solution, or most chemists have it in a very weak solution as a mouthwash. If you use a weak solution, just leave it in for longer.
I use a peroxide bought from a hair stylists suppliers in 1L for about £3 - strong as possible and it does the trick wet or dry...
I got some peroxide from the hairdresser that comes to our house. Pasted on, cover and left it for a couple of hours. The skull was dry and it came out ok.