Buckram or linen cardboard was often used in period as support, though the buckram of the 16th century would have been very different to what we know now. We know starch would have been used to set ruffs, and it's likely animal glue, as it was in use in bookbindings, would have been used to make linen cardboard. However, animal glue is likely to crack and shrink as it ages, and given my curves, something that would crack as it conforms to a shape other than a books spine would not be ideal, so I've decided to test a variety of substances, such as a polymer, starch and cellulose. In other words PVA glue, aka white glue, home made clothing starch made with cornstarch and wallpaper paste.
All three can be used as stiffening agents, though all three have the drawback of dissolving if they become wet. It's a risk, but sure let's try it.
I made up small samples of all three solutions. For the PVA, I used roughly a 1:1 ratio of glue to water, the starch recipe came from Janet Arnolds Patterns of Fashion, which is to use one cup of starch to 100 mls of water, mix, then add 250mls hot water, and I made up 100mls of wallpaper paste following the packs instructions for the strongest solution. I brushed three approximately equally sized pieces of linen with each solution, and I've now left them to dry. As the starch is only really activated when it's ironed, I'll be pressing all three when they dry, to keep the playing field even.
And if these don't work, the other option is to try cording. Cording involves sewing cotton cord or twice into narrow channels along the bodice. It's a technique I've tried before on the sewing machine, and it gives a very comfortable support, though I'm not sure about trying it by hand. There are only two months lefts to the competition after all.