Blotting paper is a type of paper or other material which is used to absorb an excess of substance (such as ink or oil) from the surface of an object.

Examples of its use include absorbing the excess ink left on parchment after writing with a fountain pen, removal of excess lipstick or facial oils in cosmetic testing, or removal of excess dye after staining.

When used to remove ink from writings, the writing may appear in reverse on the surface of the blotting paper, a phenomenon which has been used as a plot device in a number of detective stories.

Blotting is frequently necessary when using dip pens and occasionally when using fountain pens. This was first done by sprinkling pounce over the wet ink. Blotting paper is reputed to be first referred to in the English language in the 1400s but there is a tradition in Norfolk, England that it was invented by accident at Lyng Mill on the river Wensum. This may be wrong as this was expressly a paper mill until about 1830, although it is clear that it did make paper before this time as it was referred to as Mr Hamerton's mill and there are many texts describing it as a paper mill in the 18th Century. However, the process of making blotting paper in bulk rather than by hand may be what was created at Lyng.

Certain drugs, most notably LSD, are distributed on blotting paper. A liquid solution of the drug is applied to the blotting paper, which commonly is perforated into individual doses and artfully decorated also known as blotter art.

Blotter art

Blotter Art is a term for the artwork that LSD is dropped onto. The artwork is printed onto "blotter" paper and then perforated into tiny squares which can be torn apart.