Who went to school without ever getting stuck in the hand - it's hard to clean every time, why?

Let's go find the reason why when they get stuck in the ink, they wash it a little bit clean, while the other solution is not so hard.

When going to school, the squid caused both hands to smudge. By the time I got home, I used soap to wash forever and forever, not clean. Why is that?

Cleansing off sticky ink on hands is always more difficult than other stains on the skin. This can be explained by the interaction between the composition of the ink and the structure of the skin.

These "ink particles" can get down to the surface of the skin because of their microscopic size.

Writing ink contains a solvent like propyl alcohol. This solvent usually dissolves quickly and penetrates deep into the horny layer of the skin. When you look at the stain, you may think that the ink only clings to the surface of the skin.

But in fact, a small amount has penetrated the surface and moved into the skin. These "ink particles" can get down to the surface of the skin because of their microscopic size . They are much smaller than the blood cells in our body.

Therefore, when you wash the sticky ink on your hand, you actually only erase the "ink particles" located on the surface of the skin. And the "ink particles" absorbed under the horn layer of the skin are not soluble in water, so they are still very stubborn and must be washed several times with soap to remove.

Compare with other stains, such as blood stains. The composition of blood is completely different from the ink so the interaction of blood with the skin is also different. In fresh blood is mainly water but the skin is not waterproof. Furthermore, blood cells are large in size, so they cannot be passed through cells on the surface of the skin. So fresh blood stains on the skin easily washed away.

Blood does not penetrate through the skin, so it washes away faster.

However, if the blood stains are left dry, the washing will be a little more difficult. Because blood will undergo a chemical reaction, freeze on the spot. This is its inherent coagulation mechanism to prevent blood loss in cases of injury.

A tip for you to quickly fly dry blood on skin or clothing is to use cold water instead of hot water.