Slashing At High Hydration

I've just been baking a sifted whole wheat miche (70% hydration) with excellent gluten development and fairly short proofing times (4 hours bulk, 1 hour after shaping)...but I can't for the life of me understand how you are supposed to slash this dough. As soon as I turned out the boule onto a baking sheet to transfer to the oven, the dough flattened out considerably.

Plenty of oven spring prevented it from looking like a complete pancake but I'm still puzzled how it would be at all possible to slash this loaf - and if so - when and how should I do it?

I've seen pictures here of 82% hydration slashed loaves and I can't figure out how you'd do that? It's simply not possible as far as I can tell. There was no way I had time to slash the loaf after it started flattening...literally I had about 10 seconds to get it from the baking sheet to the oven.

Please can someone tell me how to defy physics!

Thanks

Defying physics is easy! You just can't change it. A couple of my bread books recommend using scissors to "slash" slack doughs. I think it also helps to make sure you have fully developed the gluten in your dough and shaped your loaves with a good "skin" of gluten, without weak areas. That said, I have sometimes gotten good oven spring but not a really good bloom on slack dough breads. I do fine with hydration up to about 72%. Beyond that ... Well, my last blog entry on Leader's "Baguettes a l'ancienne" is a fair example. <sigh>
David