bending plywood for the scutum

[Marcus Mummius]

Salve omnes,

I've got a problem with the wood I want to use to make a couple of scuta... It's birch triplex, very nice and strong wood but very difficult to bend! Can anyone please offer me some advice on how to make the bending of the wood easier?

We're using a simple press like the one you can see over here (the one at the top of the page):
http://www.larp.com/legioxx/scupress.html

Soaking it in water? Or water and glue? Something else?

Thanks in advance for the help,
Kind regards,
Jef