Cosmetics grade 99% Calcium thioglycolate CAS 814-71-1

What is calcium thioglycolate? How does it work? What are all the cosmetic applications?

1. What is Calcium Thioglycolate? How does it work?

Calcium thioglycolate, also known as calcium mercaptoacetate or calcium 2-mercaptoacetate, is the calcium salt of thioglycolic acid (CAS 68-11-1). It is one of the most classic active ingredients in cosmetic hair removal and perming products. Its molecular formula is:

C4H6CaO4S2 (Ca(OOCCH2SH)2, molecular weight approximately 222.30; CAS No.: 814-71-1; CAS No. for trihydrate: 14237-47-9)

It is a white or off-white crystalline powder at room temperature, with the characteristic pungent odor of thiols (mercaptoyl groups) (similar to rotten eggs/hydrogen sulfide). It is soluble in water (in appropriate amounts), and its aqueous solution is strongly alkaline (pH approximately 11-12). It is highly reactive and easily oxidized and deteriorated in air (the thiol group is oxidized to disulfide and becomes ineffective). It must be stored in a sealed, moisture-proof, and light-protected environment. In the cosmetics industry, it is refined by reacting thioglycolic acid with calcium hydroxide to form a salt.

Structurally, calcium thioacetate consists of two thioacetate groups (-SCH2COO-) and one calcium ion (Ca2+). Each thioacetate group carries both a reducing thiol group (-SH) and a carboxylate group (-COO-): the thiol group acts as "scissors" to break keratin disulfide bonds, the carboxylate group is responsible for forming salts with the calcium ion to form a stable paste base, and the calcium ion provides a mild alkaline environment to the formula. This is the structural basis for its use as an active ingredient in hair removal and perming.

Chemically, the most crucial property of calcium thioglycolate is the strong reducing power of its thiol groups: it can reduce and break the disulfide bonds (-SS-) in keratin, such as those in hair and nails, into two thiol groups (-SH), causing the keratin structure to disintegrate and the hair to soften and fall out. This reducing power is significantly enhanced under alkaline conditions (pH 10-12). Simultaneously, the thiol groups are easily oxidized by air to disulfide bonds (becoming ineffective), therefore, the product requires the addition of antioxidants and must be stored in a sealed container. Storage should be airtight, moisture-proof, protected from light, and away from oxidants.

From the perspective of its mechanism of action, calcium mercaptoacetate exerts its effects through the unique properties of "disulfide bond reduction + alkaline softening + calcium salt support + oxidative regeneration," and its mechanisms of action in different applications are as follows:

1.Disulfide bond reduction mechanism (core mechanism)

The strength and toughness of hair keratin come from a large number of disulfide bonds (-SS-) crosslinking; the thiol group (-SH) of calcium thioglycolate can reduce and break the disulfide bonds in hair keratin into two thiol groups (-SH), causing the originally hard and tight keratin structure to disintegrate and the mechanical strength to drop sharply. As a result, the hair becomes soft and fragile and breaks easily when rubbed. This is the common chemical basis of hair removal and perming (discovered by David Goddard in the 1930s).

2.Alkaline softening mechanism (keratin swelling)

Calcium thioglycolate aqueous solution is strongly alkaline (pH 11-12). The alkaline environment causes hair keratin to swell, hair cuticles to open, and the structure to loosen. At the same time, it significantly enhances the reducing activity of thiol groups, thus accelerating hair softening and breakage through a two-pronged approach. This is why hair removal creams need to maintain a high pH (regulations limit pH ≤ 12.7).

3.Calcium salt carrier mechanism (paste form and mildness)

The calcium salt form allows thioglycolic acid to exist in a stable solid state, making it easy to formulate into creams. Calcium ions also participate in maintaining the alkaline buffer system of the formula. Compared with ammonium salts (such as ammonium thioglycolic acid), calcium salts have relatively controllable irritation and good cream stability, making them one of the preferred salt types for hair removal creams.

4.Oxidative regeneration mechanism (perming and styling)

During the perming process, calcium thioglycolate first reduces and breaks the disulfide bonds in the hair keratin, softening the hair before curling and shaping it. Then, an oxidizing agent (such as hydrogen peroxide or bromate) is used to re-oxidize adjacent thiol groups into new disulfide bonds, "locking" the curl shape and achieving a long-lasting perm/straight hair style.

In summary, calcium thioglycolate is a "dual-purpose" thioglycolate-reduced cosmetic ingredient: as a hair removal active ingredient, it softens and removes hair by breaking keratin disulfide bonds; as a perming reducing agent, it reshapes hair through a reduction-oxidation cycle. It is one of the most classic thioglycolate salts used in cosmetic hair removal and perming products.

II. What are all the uses of cosmetic-grade Calcium thioglycolate?

1.Active ingredient for hair removal products (core application for standard hair removal)

Application Field: Personal care, hair removal

Corresponding Products: Hair removal creams, hair removal mousses/sprays, hair removal products for sensitive areas including face and bikini line, men’s body hair management products

Applicability Principle: After applying these hair removal products, the thiol groups of calcium thioglycolate penetrate the hair shaft, reducing and breaking keratin disulphide bonds, softening and embrittling hair from the root. After several minutes, hair can be easily scraped off to realise “root softening and painless hair removal”. It is the classic active ingredient in depilatory creams, in use since the 1940s. Different formulations (creams/solutions/mousses/sprays) only differ in carrier base, while the core reduction mechanism remains identical. Formulators adjust concentration, pH and add soothing ingredients to control irritation for sensitive-area formulas and men’s products. It also acts as an alkaline component in formulations, forming a buffer system with calcium hydroxide to maintain hair removal pH (regulatory limits: concentration ≤5%, pH ≤12.7) and enhance thiol reduction activity.

2.Reducing agent for hair perming agents (cold perm solution) (hair industry)

Application Field: Hair styling, perming

Corresponding Products: Cold perm lotion, perm solution, curl styling products

Applicability Principle: In the first stage of cold perming, a reducing agent breaks disulphide bonds inside the hair shaft to soften hair and make it malleable. Thioglycolate (calcium/ammonium salt) acts as the active reducing agent in this step. Once hair is softened and curled, an oxidising agent rebonds and sets the curls, delivering a long-lasting curly effect.

3.Hair straightening and styling agent ingredient (hair care industry)

Application Field: Hair styling, hair straightening

Corresponding Products: Straightening cream, straightening agent, straightening treatment

Applicability Principle: The underlying principle of hair straightening is similar to perming. Calcium thioglycolate reduces and breaks disulphide bonds to relax frizzy and curly hair. After straightening, oxidants re-crosslink keratin and fix the shape, “locking” straight hair, reducing frizz and achieving long-lasting straightness. This is the fundamental principle of chemical hair straightening products.

4.Nail softening agent (hand and foot care area)

Application Field: Hand and foot care, nail care

Corresponding Products: Nail softeners, ingrown toenail correction and care products

Applicability Principle: Nails are also composed of keratin. Thioglycolic acid and its salts can soften thickened or deformed nail plates (such as ingrown toenails) to facilitate correction and shaping.

To summarise, calcium thioglycolate (CAS 814-71-1) is the classic thioglycolate reducing active ingredient for cosmetic hair removal and hair care industries. It features four core mechanisms: disulphide bond reduction, alkaline softening, calcium salt carrier, and oxidative regeneration. It has mature applications across hair removal (hair removal cream / hair removal mousse / hair removal spray, sensitive-area depilation, men’s body hair management), hair care (cold perm lotion, hair straightening agent), and hand & foot care (nail softening). Its basic function of breaking disulphide bonds and softening keratin makes it one of the most widely used thioglycolates in depilatory products and has been applied since the 1940s.