What are oil absorbing sheets made of

Oil absorbing sheets are typically made of a thin, absorbent material such as paper or synthetic fibers. They may also contain additional ingredients such as charcoal or clay to enhance their oil-absorbing properties. 

Some brands may use natural materials like hemp or bamboo in their products.

Why do oil absorbing sheets turn clear?

Oil absorbing sheets turn clear because they are designed to absorb excess oil and sebum from the skin. When these sheets come into contact with the skin, the absorbent material in the sheet pulls the oil away from the skin's surface and into the sheet. 

As the sheet absorbs more oil, it becomes more transparent or clear.

The absorbent material in the sheet works by using capillary action. Capillary action is the ability of a liquid to flow in narrow spaces without the assistance of, or against, external forces like gravity. 

When the oil comes into contact with the absorbent material, it is drawn up into the tiny spaces between the fibers in the sheet. This process continues until the sheet has absorbed as much oil as it can hold.

As the sheet absorbs more oil, it becomes more transparent because the oil is no longer visible on the surface of the sheet. Instead, it is trapped within the fibers of the sheet. 

This is why oil absorbing sheets are often referred to as "blotting" sheets - they literally blot the excess oil from the skin's surface.

In summary, oil absorbing sheets turn clear because they are designed to absorb excess oil from the skin's surface using an absorbent material that uses capillary action to draw the oil into the sheet's fibers. 

As the sheet absorbs more oil, it becomes more transparent because the oil is no longer visible on the surface of the sheet.