Tallow and lard are not the same fat

Both jars look like pale fat on a counter, so the labels get used as if they were the same word. They are not. Tallow is rendered fat from beef or sheep. Lard is rendered fat from a pig. Suet is the hard beef fat before it is rendered, the kind from around the kidneys. Leaf lard is the pork fat from that same place, and it is the quietest lard for pastry. Once either fat is melted, strained, and cooled, it is tallow or lard. Before that, it is just fat and scrap.

How they behave

Tallow is firmer at room temperature. You can cut it into pieces that hold an edge. Lard yields to a spoon. That is the fat itself, not a trick of the jar. Tallow carries more of the harder fatty acids. Lard is softer, which is why a pie crust made with leaf lard flakes, and why a bar of soap made with a lot of lard is softer than a bar made with tallow.

In the skillet they part ways again. Clean, dry tallow takes a high heat and is what this house uses when a recipe is fried in beef fat. Lard is the better fat when you want layers in a crust. The biscuits on this site use cold butter, not either jar. Butter is a third thing, water and milk solids included. Do not swap them one for one and expect the same flake or the same smoke.

How to tell a clean jar

Well-rendered tallow is ivory and nearly quiet in smell. If it smells strongly of roast, it still has meat and water in it, and it will not keep or make a mild soap. Lard should not smell like bacon unless you rendered smoked scraps on purpose. Bacon grease is delicious and it is not pastry lard. Strain either fat through a fine cloth while it is warm, and do not jar it until the bubbling of water has stopped. Water left in the fat is what makes a jar sour.

• Firm, ivory, almost no smell: tallow, for frying, soap, and a plain balm.
• Softer, spoonable, neutral: lard, especially leaf lard, for crusts.
• Smoky and brown bits in the bottom: bacon grease. Use it where you want that taste. Do not call it leaf lard.
• A jar that smells stale or paint-like: it is rancid. Soap and pastry will not fix that.

This house keeps tallow for the pan, the skin, and the soap. That is a use, not a cure. The longer note on those uses is the tallow essay. Lard can live in the same kitchen. It should live in its own jar, with its own job.