This subject arose on another blog. As an initial blog post, I offer these photos as illustrations of my idea of a translucent crumb. I hope that the photos adequately show this characteristic.
I am not a science guy. I can't tell you how it happened. I can say that these breads, a 100% whole wheat sourdough and a basic sourdough boule, were roughly 70% hydration, mixed by machine, bulk fermented for about 4 hours at about 80 degrees and proofed overnight, formed, in the refrigerator. They were baked on preheated stones, with steam but no cover. The white flour is KA AP; the whole wheat, Bob's Red Mill.
I find that the stretch and fold breads that I've been making lately, baked covered but without steam, produce a somewhat cake-ier crust and, of course, the beautiful open structure. Guests and gift recipients are more impressed with the stretched and folded breads, but I think the former ones taste better and are more fun to eat.
Comment and criticism invited.