Fat separators are specially designed measuring cups that make it easy to de-fat stock for gravies and sauces. They can also be called gravy strainers or soup strainers. By separating the broth and fat from your pan drippings, you are able to produce a flavorful, lean broth and retain the fat for other purposes.
There are three basic styles of fat separators: pitcher-style measuring cups – like our pick, the OXO Fat Separator, ladles with slots around the perimeter and fat mops (brushes with long, soft bristles). All of these styles work because of the basic molecular makeup of the drippings – the fat and water in them can’t mix, and the fat will always rise to the top because it is less dense than water.
Cooks Illustrated has an extensive review of the different styles of fat separators, or you can take our word for it and stick with the more traditional spout-style fat separator. Our pick for a fat separator is the OXO Fat Separator with a 4-cup capacity (it’s better to have extra space when working with stocks!).