Hi,

Thanks Pembroke,

You couldnt have been more helpful! unfortunately i hadnt seen this before i just went for it and essentially created a silicone coffin for the poor sparrow (which WAS dead). My attempts at sealants ultimately failed and i also didnt think to do the legs in a separate piece. 

I will set about first getting another specimen then trying out everything u suggested. i think in the end the biggest problem was the porous nature of the bird which in turn melded itself to the rubber making removing it from the cast impossible. Most annoyingly is that i have now wasted a significant part of my "kit". I clearly underestimated this project.

I have read your post a while ago and kept thinking of it, I think I found an idea you could test;