Funnels are used to direct liquids into containers that have small openings. In scientific laboratories, funnels are sometimes used to filter materials, often with the addition of a sieve or filter paper. Cooks use funnels in the kitchen to transfer liquids, powders, herbs or other items made of fine particles into containers with a minimal amount of spillage or waste.
Specialty funnels exist for use in scientific laboratories. Some funnels contain stopcocks, which slow down the rate at which a fluid runs through a funnel. Some scientific funnels are designed to channel powder rather than fluids. Filter papers are often used to filter fine particles out of a liquid being transferred. Scientific funnels can also be designed to separate two liquids flowing through the funnel together.
Funnels used in cooking come in different sizes and shapes that depend on their intended use. Narrow funnels are usually used to transfer liquid while wide ones are better at transferring dry food such as flour.
Funnels made from varying materials are used to transfer different types of liquid. The funnel must be made from a substance that does not react with the liquid being transferred. Aluminum, glass, plastic and stainless steel are often used to make funnels.