Re: Can PUL be fixed once damaged?
I don't think it would work at all. Lanolizing wool replaces the natural oils that wash out with use. Lanolized wool is water resistant, but not waterproof, and can also absorb moisture without feeling wet. This is a natural function of the wool when it is still on the animal, and is created by the microscopic structure of the hairs.
PUL fabric, on the other hand, is mean to be a waterproof barrier. When it gets damaged, it has small cracks or other perforations. Lanolizing it with the oils from a sheep's skin (lanolin) would make it a little oily, but wouldn't be effective to close the perforations. I'm guessing the spray forms a chemical film/skin that can cover the tiny perforations, restoring the waterproof quality of the PUL until it breaks down/washes out.