Have you ever wondered why the skin on a bald man’s head is shiny but skin everywhere else on the body isn’t? The following five explanations from the internet should answer your question.
Your head secretes an oil called sebum and it still does so even after you lose your hair. Not washing your hair for a few days will make it oily, the same oil makes your bald head shiny without the hair.
All skin does this, but the top of the head does it more. Fun fact: the reason you get acne around puberty is because we used to have way more hair on our bodies but the sebum oil glands never quite got the memo that the hair is far less prominent. The glands are producing excess oil which can clog pores and traps dirt/dead skin/dust (blackheads) or harmful bacteria (white heads).
On top of the oil from your skin not being absorbed into the hair, some bald men also wax/buff their head. I had a teacher in high school who was bald, and he waxed his head before directing band concerts.
When hair stops growing in men, it also means that the follicles (the pores where the hair normally grows out from) shrink in time. This makes the skin smooth. And then, add the oils (sebum) which makes it look polished/shiny.
Add to that that the scalp is usually tight on the skull.
A combination of oil secreted and the fact that the skin is often pulled more taut over the skull than over other parts of the body. This is the reason people’s noses get shiny.
Additionally, there’s more light getting reflected from an overhead source. For example, bare shoulders are usually shinier than bare arms.
1st case : going bald – your hair follicles die, causing your pores to close and make you skin smoother, effectively making it more reflective (was the case with my late grandfather).
2nd case: shaving – shaving exfoliates, removing dead skin and making your skin smoother but not to the same degree as in case 1. However once the skin secretes the oil called sebum as usual, it makes the surface effectively smoother, reflecting light more.