I'm reading through some old (early 1900's) cookbooks and something that keeps coming up is beating dough "until it blisters" - here's an example.
VIRGINIA BEATEN BISCUIT. One quart flour. One teaspoonful of salt. One tablespoon of lard. Work lard lightly into the flour and salt, mix with iced water and then beat dough with rolling pin until it blisters. Cut into biscuits and bake in quick oven.
It's clearly not referring to the kinds of blisters you get on sourdough or pizza after baking it, for example. This is during the beating process.
My thoughts are either this refers to the dough kind of ripping apart when you knead it (sign of adequate hydration?) or maybe something to do with the bits of shortening in it. Any thoughts?