I would expect the opposite - urea is a keratolytic, so it should break down thickened skin, and make the hands less tough. That said, urine is 1-2% urea, and t

I would expect the opposite - urea is a keratolytic, so it should break down thickened skin, and make the hands less tough. That said, urine is 1-2% urea, and typical medical urea solutions are 5% or more, so i wouldn't expect much of an effect.