A good question, reader Suzy. Clabber is/was nothing more or less than sour milk. Rural American housewives made it either by leaving milk out at room temperature (where it would be slowly soured by lactic acid-producing bacteria), or by combining milk with vinegar or even rennet. Depending on how clabber was made and how it was treated it could assume any one of several textures. It could be thick and spoonable, it could be a soupy, lumpy consistency, or it could be firm and dry, almost like a cheese. Mostly, clabber was a way to turn something that would otherwise go to waste (excess milk) into something useful.
Clabber came to America by way of the Scots-Irish: back-country Scottish lowland folk who were relocated to Northern Ireland (Ulster), but ultimately emigrated to the New World. The poorest of the poor of our early forebears, they could afford to waste nothing. Indeed, while the English slopped their hogs with the clumpy, curdled milk that remained after their cream was skimmed off, their Northern cousins would just as soon eat it. And so, just as clabber was synonymous with poverty in the old country, so it was in America, common among Appalachian hill folk and Southern farmers. They — and especially their children — would slather it over corn bread or just eat it by the spoonful.
When American housewives began experimenting with chemical leaveners in the late 18th and early 19th centuries, clabber became useful in another way: as an acid food to combine with saleratus, soda or pearlash to make bubbles in batters and doughs.The problem was that homemade clabber could be highly variable in its acidity, and that caused problems for reasons I’ve discussed below. No wonder then that so many home bakers were so relieved to have a consistent leavener like baking powder replace the old soda-and-clabber or saleratus-and-clabber combos. No wonder also why one of the most widely marketed baking powders was (and is) named Clabber Girl.
And with that Paul Harvey-esque finale I’ll bring this post to an end.