I have yet to try this out but here is the ‘formula’:

Put white vinegar and some lemon peels in a jar.

I guess we’d have to be very careful what we used it on until we understood it’s power and also it’s ability to mark or remove stains.

Another cleaning fluid J. reminded me of is putting the little bits of left-over soap in a jar with some water. They soften and become a soapy fluid that is great for things like pre-cleaning shirt collars before they go in the washing machine.