Glass funnels are pipes with a wide mouth and smaller end that are typically used in laboratory settings. Common sizes are 40 millimeters to 100 millimeters, with varying lengths.
The narrow bottoms of funnels allow liquids to be added to chemical mixtures at a slow pace. Some funnels are used with filter paper to sift fine particles from a liquid. Glass is typically used in funnels for lab use rather than metal or plastic because it does not react with chemicals. Solvents can deteriorate plastic or metal funnels. As of 2014, glass laboratory funnels may be purchased from specialty lab ware stores as well as from general retailers, including eBay and Amazon.