Alum, or alum rock, is a naturally occurring chemical compound that’s been used for centuries in various applications. In the Ozarks alum was typically used in taxidermy and dying clothes (as the alum acts as a mordant for the dye). In medicine alum has been historically used as a strong astringent specifically in the treatment of ailments like canker sores where a strong drying effect is needed. This use of alum can be seen in the below examples for thrash or thrush and for cuts. In the case of thrash the sores inside the mouth which can be very painful for the child, would need to be dried up, and in the case of a cut the alum wound help to staunch the blood flow. In curanderismo alum rocks are often used in place of eggs during a limpia then disposed of afterward by burning.
With sage, honey, and green oak leaves for thrash – “A granny-woman in the Cookson Hill country of eastern Oklahoma treated thrash simply by putting crushed green oak leaves in the child’s mouth every three hours, and the babes in her charge recovered about as quickly as those submitted to supernatural spells. If no green leaves were handy, she used sage tea, with some honey and a little alum in it, which seemed to work about as well as the oak leaves.” ~Randolph OMF 137
For cuts – “For cuts and stuff like that mama just put cookin’ alum in ‘em to stop the bleedin’…My sister cut her foot open one time real bad and dad couldn’t stop it from bleedin’. Mom had a jar of cookin’ alum and he just took that and made a pack out of it and put it right on her foot. It drawed the cut and stopped the blood.” ~Carter and Krause HRIO 14
Carter, Kay & Bonnie Krause Home Remedies of the Illinois Ozarks (HRIO)
Randolph, Vance Ozark Magic and Folklore (OMF)
Source: Ozark Encyclopedia – A – Alum