|This article is about an older version of DF.|
Tallow is the rendered form of animal fat. Tallow is made from fat by the 'render fat' job in a kitchen; fat is obtained from butchering animals. Tallow is used to make soap, and can also be used as a low-value "solid" ingredient for cooking prepared meals. Since tallow does not have quality levels, rendering fat is a good, but slow, way to train a cook. However, this also means that forbidding tallow from the kitchen menu is a must for players looking to create expensive Lavish Meals to trade or to help keep dwarves happy.
The standing orders workshop menu includes "Auto-Kitchen" (enabled by default), which will automatically schedule 'render fat' jobs on any available kitchen. Once your dwarves have produced enough tallow to last for years you may want to disable the "Auto-Kitchen" task to keep your cooks focused on more important jobs.
Note that although fat will be created as a stack, the 'render fat' job will only render one piece of fat at a time, effectively splitting the stack into a bunch of single pieces of tallow.
It is stored in food stockpiles and found under fat. Tallow can be stored without a container, but if barrels are available dwarves will fill up to 50 units of random tallow in one barrel.
Currently tallow will never rot, even if not stored on a stockpile.
For real-life information on tallow, view the Wikipedia page.