Calcium Hydroxide

Calcium Hydroxide

AKA “1305-62-0, Slaked lime, Hydrated lime, Lime hydrate, Calcium hydrate, Lime water, Calcium hydroxide (Ca(OH)2), Hydralime, Slaked-lime”

Ingredient

Ingredient Facts

Calcium hydroxide

AKA: 1305-62-0, Slaked lime, Hydrated lime, Lime hydrate, Calcium hydrate, Lime water, Calcium hydroxide (Ca(OH)2), Hydralime, Slaked-lime

Ingredient · Buffering · EWG: 4

Synthetic

Not Clean

The CIR Expert Panel concluded that ... Calcium Hydroxide is safe in hair straighteners and depilatories under conditions of recommended use; users should minimize skin contact. These ingredients are safe for all other present practices of use and concentration described in this safety assessment when formulated to be nonirritating.

Solubility 0.2 % at 32 °F (NIOSH, 2024)

Formula

CaH2O2

Mol. Weight

74.09

CAS #

1305-62-0

Form

Powder

State

Calcium hydroxide is an odorless white granules. Sinks in water. (USCG, 1999)

See origin →

Functions

Buffering

Antioxidant

Anti-Inflammatory

Boosts Collagen

Maintains optimal pH

Traditional Use

Used historically as slaked lime in traditional cosmetics and body preparations, particularly in South Asian and Middle Eastern beauty rituals. Also employed in traditional Chinese medicine; modern cosmetics use it as a pH buffer and neutralizer.

Skin Types

●all-skin-types

Best For

General

Pregnancy & Breastfeeding Safe

Yes

EWG

CIR

Safe as used

Pregnancy

Yes

CIR Safety Findings

Not a Sensitizer

ewg-4

medical-approval

all-shades-safe

Concentration Guide

7%

0%10%

Reg. Limit

EU regulatory limit: 7%. (a) Contains alkali Avoid contact with eyes Keep out of reach of children Can cause blindness (b) Contains alkali Keep out of reach of children Avoid contact with eyes Source: EU Cosmetics Regulation (EC) 1223/2009, Annex III (Restricted Substances), Entry 15c.