Hi so i have been shopping around and looked into trying to find mylar backing half back/full back boards that were cheap. I have found something on this page here:

http://www.forbidden-planet.co.uk/acatalog/Boxes__Bags___Boards.html

Scroll down to the "50 Calcium Buffered Comic Boards" by the company Collectorline.

But i am not sure if they are half/full back boards as such. I fee they may be just slightly more expensive, ordinary comic boards, but the name sounds to me like they are something a bit more. What size are they too, i think by the size they would be silver age? Any help?