Blotter paper

Blotting paper, sometimes called bibulous paper, is a highly absorbent type of paper or other material. It is used to absorb an excess of liquid substances (such as ink or oil) from the surface of writing paper or objects. Blotting paper referred to as bibulous paper is mainly used in microscopy to remove excess liquids from the slide before viewing. Blotting paper has also been sold as a cosmetic to aid in the removal of skin oils and makeup.

Blotting paper is made from different materials of varying thickness, softness, etc. depending on the application. It is often made of cotton and manufactured on special paper machines. Blotting paper is reputed to be first referred to in the English language in the 15th century but there is a tradition in Norfolk, England that it was invented by accident at Lyng Mill on the River Wensum.

It is reported that a Berkshire (England) paper mill worker failed to add sizing to a batch of paper that was being produced. The batch was discarded. Subsequently, someone tried to write on a piece of this discarded "scrap" paper and found that it rapidly absorbed any ink applied, making it unusable for writing. Its marked absorbency having been noted, however, led to its subsequently being produced and used as blotting paper, replacing sand, which was the material that had been used for absorbing superficial wet ink. In a time when most paper was produced from "rags", red/pink rags, from which it was difficult to remove all color and had generally been discarded, were now directed to the production of blotters, hence the historically characteristic pink color of blotters.

A form of blotter paper commonly known as watercolor paper is produced for its absorbent qualities, allowing much better absorption of water and pigments than standard art or drawing papers. Although usually categorized as separate from blotting paper, differences in the constituents and thickness of blotting paper and watercolor paper are subtle, and making a distinction between the two is unnecessary as the production process is nearly identical.

Blotting paper is used in chemical analyses as stationary phase in thin-layer chromatography. Blotting paper is also used in pool/spa maintenance to measure pH balance. Small squares of blotting paper attached to disposable plastic strips are impregnated with pH sensitive compounds usually extracted from lichens, especially Roccella tinctoria. These strips are used similarly to litmus strips, however filter paper is usually used for litmus strips, generally to allow for the property of diffusion.

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