Knight appears human in normal circumstances, although he rarely perspires and when he does, he does not perspire sweat, but rather blood and his skin is cold to the touch.
en.wikipedia.org He became ill whenever he perspired, and suffered from phobias about water, wind, cold, light, and noise.
en.wikipedia.org Perspiring slightly, we listened with rapt attention, taking a swig of wine for good measure.
observer.com People perspire; and so foams used for the construction of matrasses or furniture will, over time, tend to feel softer and give less support.
en.wikipedia.org