The human body and brain knows and understands the laws of physics better than we consciously know and realize. Many unconscious and spontaneous body processes have proved it again and again, and the new revelation about how we hold glass makes it even prominent.
Adaptation to holding a glass surface
The human skin takes almost 20 seconds to adapt to a glass surface to hold any glass object better with a strong and secure grip.
This has been revealed in a study about how the human skin balances the skin surface area to increase friction, and make the grip secure in case of smooth and hard objected surfaces like glass.
The skin on hands has grooves and patches, which makes for the finger prints of human. This shows that the skin is not a flat surface, and is undulating on close view.
Thus the surface area of actual contact while holding a hard surface may be small other than holding a soft surface. Soft surfaces get a better grip because the pliable folds of skin soon spread over the surface.
What is the mechanism behind holding of glass
The mechanism that leads to holding the glass is supported by the process of sweating. The human skin changes its surface area of contact while holding the glass object. Otherwise the glass surface feels too smooth and may slip off the hand.
But little amounts of sweat is expelled by the sweat glands on the skin, to moisten the exterior sin layer enough to make is soft and pliable for flattening the ridges in contact of the glass surface.
As a result, whether you hold a glass cup or tumbler, or a showpiece etc, your skin flattens under the influence of sweat to increase friction, and keep the smooth and hard glass surface secured in grip.
The formation of the sweat happens at a different speed for different people. Some people get their hands sweaty in just 2 seconds of holding a glass item, and some may take 20 seconds to get their finger skin seasoned in sweat for the best grip.
Again age, and individuality matters. Not all men and women have the same amount of sweat glands and production speed, all of which contributes to the total timing while making it an estimated 20 seconds process in average to grip a glass surface securely while changing skin surface area.
The whole process depends on the law of friction in physics and shows how the human brain applies this even before you started reading physics.