Guanidine Carbonate

What is Guanidine Carbonate?

Guanidine carbonate is a white, crystalline inorganic salt formed from guanidine, a strong organic base, and carbonic acid. In cosmetics, it belongs to the category of hair treatment agents and formulation aids. Primarily, it functions in hair waving and straightening products by reacting with water and other alkalis like calcium hydroxide to generate guanidine hydroxide in situ. This mild alkali breaks disulfide bonds in hair keratin fibers, allowing permanent reshaping during reducing steps of chemical services. It also acts as a pH adjuster to fine-tune acidity levels for optimal ingredient activity and comfort, a buffering agent to resist pH changes from external factors, and a skin conditioning agent that helps maintain moisture and suppleness on scalp or skin surfaces.

Comedogenic Rating 0/5 Low risk of clogging pores
EWG Safety Rating 1 View on EWG →
PubChem View on PubChem →

Roles in Formulation

This ingredient serves the following purposes in cosmetic formulations:

Hair waving or straightening
Reshapes hair by breaking and reforming bonds in the fiber (often via reducing/oxidizing steps), enabling permanent waves or straightening services/products.
PH adjuster
Raises or lowers pH to the target range, supporting ingredient performance, preservative efficacy, stability, and user comfort.
Buffering agent
Maintains the pH stability of a formulation.
Skin conditioning agent
Maintains skin softness, smoothness, and flexibility.

Benefits

Facilitates permanent hair reshaping by altering keratin structure.

Stabilizes product pH for consistent performance and efficacy.

Promotes skin and scalp softness through conditioning effects.

Who It's For

A quick guide for who this ingredient may suit (and who should be cautious).

Who May Benefit Who Should Avoid
Individuals seeking chemical hair straightening or waving services.
People with scalp abrasions or open wounds.
Users of pH-sensitive formulations needing stability.
Individuals prone to alkaline sensitivities.
Those desiring smoother skin feel from conditioning products.
Users of no-lye hair relaxers with misuse history.

Safety Notes

  • Regarded as safe for cosmetic use in established concentrations.
  • Rinse thoroughly after hair treatments to minimize residue.

Frequently Asked Questions about Guanidine Carbonate

What does guanidine carbonate do in hair products?

It generates alkali to break hair bonds for straightening or waving, while adjusting pH.

Is it safe for skin contact?

Yes, as a conditioning agent in low concentrations, supporting skin softness.

Can it buffer formulations?

Yes, it maintains pH stability against changes for product reliability.