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Calcium hydroxide

Calcium hydroxide suppliers and sourcing guide

Calcium hydroxide is an alkaline inorganic compound made by adding water to quicklime (calcium oxide), which is itself made by heating limestone. The result is a fine white powder that dissolves only slightly in water. Food brands buy it for nixtamalizing corn for masa and tortillas, firming pickles, adjusting pH and as a calcium source, and it is also used in sugar refining and water treatment.

See suppliersWhat to ask for on the COA
Also known as
Slaked lime · Hydrated lime · Pickling lime · Cal · E526
Facts checked
November 2026

Forms and grades of calcium hydroxide

Suppliers sell different products under the same name. Specify the one you need.

  • Food grade powder (FCC)

    Fine powder tested to the Food Chemicals Codex, the usual form for food processors.

  • Pharmaceutical grade (USP)

    Material tested to the USP monograph, used in some supplements and drug products.

  • Technical grade

    Lime for water treatment and construction, not suitable for food.

  • Lime water or slurry

    Calcium hydroxide suspended in water, prepared on site or bought for continuous dosing.

What to check on the COA

Compare each result with your own specification when the lot arrives.

Assay (titration)
Calcium hydroxide content, usually 95 percent or more.
Carbonate
Calcium carbonate formed by reaction with air, a check on how fresh the lot is.
Acid-insoluble substances
Sand and other insoluble matter from the limestone.
Magnesium and alkali salts
Impurities from the limestone source.
Fluoride
A Food Chemicals Codex limit for food-grade lime.
Heavy metals
Lead, arsenic and other metals by ICP-MS or ICP-OES against the supplier's specification or the Food Chemicals Codex (FCC) limits.

Storage, lots and expiry

Storage and shelf life

Store calcium hydroxide in sealed bags in a dry area, because it reacts with carbon dioxide in air and slowly turns into calcium carbonate. Keep it away from acids, and handle with eye and skin protection because it is caustic. Shelf life follows the supplier's specification, and older stock is retested for assay and carbonate.

Lots and expiry dates

Record the grade and assay for each lot, and keep the limestone source and heavy-metal results on file, since metals vary with the quarry. Use open bags quickly and rotate stock first-in, first-out.

Regulatory status

Facts from regulators and standards bodies, each linked to its source.

This is general information, not regulatory advice. Status differs by country and by how the ingredient is used, so check the rules for your product and market.

Calcium hydroxide suppliers

Manufacturers and distributors whose own websites say they sell it.

We are checking calcium hydroxide suppliers now

Every listing is checked against the supplier’s own website before it goes live, so this list fills in over the coming weeks. The specs and COA checklist above are ready today.

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Frequently asked questions

What forms of calcium hydroxide can brands buy?

Common forms include food grade powder (FCC), pharmaceutical grade (USP), technical grade and lime water or slurry. Ask each supplier for the specification sheet of the exact grade they quote.

What should the COA for calcium hydroxide include?

Expect assay (titration), carbonate, acid-insoluble substances, magnesium and alkali salts, fluoride and heavy metals, each with its method, specification and result for that lot.

How should calcium hydroxide be stored?

Store calcium hydroxide in sealed bags in a dry area, because it reacts with carbon dioxide in air and slowly turns into calcium carbonate. Keep it away from acids, and handle with eye and skin protection because it is caustic. Shelf life follows the supplier's specification, and older stock is retested for assay and carbonate.

What is the regulatory status of calcium hydroxide?

21 CFR 184.1205 affirms calcium hydroxide as GRAS for use in food with no limitation other than current good manufacturing practice. 7 CFR 205.605(b) lists calcium hydroxide among the synthetic substances allowed in or on processed products labeled organic. Health Canada's List of Permitted Acidity Regulators and Acid-Reacting Materials includes calcium hydroxide.

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