A coffee filter is a utensil used during coffee brewing, for filtering coffee grounds from the brewed liquid. It is usually made of disposable paper with filaments approximately 20 micrometres wide. The fine paper screen only allows to pass through particles less than approximately 15 micrometres. This enables it to trap the coffee grounds that are bigger. The small water particles and the fines can flow through, resulting in clear coffee.
The paper filter is the most popular filtering method in coffee brewing. It was invented in Germany by Melitta Benz, in 1908. The coffee brewed with a paper filter is clear, with a light body, and almost no coffee oils.
A metallic mesh filter is appreciated by coffee lovers who want a coffee with more body. The metallic mesh only retains the coffee grounds, and allows coffee oils and soluble solids in coffee to pass through. In contrast, a paper filter will retain most of the oil in coffee. For this reason a paper filter will reduce the amount of cafestol and kahweol, the substances responsible for stimulating cholesterol production in our body.
A stainless steel filter is used to prepare Indian filter coffee, the form of coffee common in India. A golden tone filter is said to improve the taste of coffee, though many coffee lovers admit it might be just a suggestion.
Coffee filters are mostly used for making drip coffee and employed with both automatic and manual drip coffee makers.