When Ed Okie and I were developing alternative ways to make Pain a
l'Ancienne, using hydrations of 85-90% we had marvellous crusts, lovely,
big-holed structure and crumb that had the texture of a wet sponge. The
extreme moisture levels in the baked bread softened the crisp crust to the
texture of damp shoe leather on cooling.
We solved the problem by extended baking times, Ed from cold start and
myself, in less iconoclastic fashion, from 250C, reducing oven temperature
by 20C after 5 minutes then 10C steps every 5 minutes until the internal
temperature of the loaf was 100C (that is not a typo). For a ficelle
weighing 110 grams, which is a very small loaf, reaching this internal
temperature took over 30 minutes, this for a loaf that, made with "normal"
(whatever that means) baguette dough at 60% hydration, would take 10-12
minutes to bake.
So, initially, make small, thin, loaves, bake them for, a long time at
reducing temperatures and, if you don't have a probe thermometer, buy one
and keep baking to 100C internal temperatures.
I would appreciate feedback on your experiences with this baking regime,
hard information about very high hydration doughs is dificult to come by.