As of 2015, you can buy hydrated lime from home centers, such as Lowe's and The Home Depot, in large quantities and at low prices. Hydrated lime is also available from numerous online retailers, though it typically has a high shipping cost due to its considerable weight. Food-grade hydrated lime, usually called pickling lime or slaked lime, is available from canning stores and the canning sections of many supermarkets.
Hydrated lime, slaked lime, slack lime and pickling lime are all the same chemical, calcium hydroxide. The name hydrated lime typically applies to calcium hydroxide used for mixing plaster or mortar, and these products often contain impurities and harmful chemicals. Food-grade calcium hydroxide is a much purer product but is also much more expensive than construction-grade products. Food-grade hydrated lime is used in pickling eggs, cucumbers and peppers, and it used in turning corn into hominy for grits and masa for tortillas.
Do not confuse hydrated lime with regular lime, also called quicklime. Quicklime is the common name of calcium oxide, and this chemical is actually the precursor material for hydrated lime. When mixed with water, quicklime molecules bond with hydrogen atoms from the water, forming calcium hydroxide. This reaction is highly exothermic, meaning that it gives off heat. Products containing quicklime are often used as hand and seat warmers for this reason.