Everyone please remember that oxalic acid and glycerin on shop towels is not an approved (legal) method to control Varroa mites in your bee colonies. As far as I know, the formulations you can find here and there online are tested by individuals, often on very few hives – sometimes as few as 1 or 2 during one season. Efforts like this in the past have often resulted in poor/no mite control or dead colonies from overdosing. As we all know, a lot of the stuff you see online is often advanced by people who have little experimental experience and often poor experimental design. Following those formulations makes your bees part of those weak experiments. My suggestion is to wait for controlled studies run by recognizable research folks so you’re sure you can get good mite control and not brood, queen, or colony damage.