Generally speaking, the material of leather strap can be divided into crocodile skin, lizard skin, shark skin, ostrich skin, calf skin and so on. However, no matter what kind of strap is worn close to the body for a long time, it will react with sweat stains and produce a sticky smell or hardening phenomenon. This is a normal phenomenon and will not cause harm to the body. You can wear it safely.
If the strap of a newly bought watch smells of glue, it means that the quality of the strap of the watch is not high, although it will not cause great harm to the body, but the image will be reduced. It is recommended not to buy inferior watches cheaply.