Ernest Race BA Chair restoration - tech help!  

Dear Paulanna
Considering the deep curve of the back rest, it is most unlikely that it was made of a flat plywood panel. Plywood, with the exception of more recent versions that are made to be bend, is always cross-glued. If it is only a three-ply one can bend it but even than a deep curve like that would require some help with steam or hot water. But a three-ply is only 3-4 mm thick and not suitable for a backrest. It was not unusual at the time to laminate a few layers of three-ply together on the frame but even that is doubtful.
For a moment I thought that because of the subsequrent involvement of Ernest Race in Isokon, he might have been chosen because a.o. things, his knowledge of bended wood...but the changes he mader to the bookshelf was to take out the bended wooden element...
Technically spoken I can not see how this rather elegant frame would be able to hold a plywood of thet thickness in such a deep curve, and to make that curve without cracking the plywood would be a major achievement...if at all possible. I am sure that you can find a standard curved piece that is large enough to be shaped in the original contour. I slight deformation (opening or closing the curve) in order to adapt it to the frame, is not very difficult. I do not know about the U.K. but here in north america you can buy these curved pieces off the shelf.