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BASIC VIOLET 4.

Avoid CAS 2390-59-2 / HAIR DYEING

A synthetic triarylmethane dye primarily utilized as a cationic colorant in temporary hair treatments and histological staining. Due to its significant regulatory restrictions and lack of functional benefits for the skin, it is rarely encountered in modern, high-performance skincare.

colorant

Science

Functions through ionic attraction, where the positively charged (cationic) molecules adhere to negatively charged surfaces like hair keratin. Its quaternary ammonium structure inhibits deep epidermal penetration, causing it to remain primarily on the surface of the substrate.


Research

Low confidence
Effective range 0.2–0.4%
Optimal

0.4%

Key findings

  1. 01 Health Canada assessments identify 0.4% as the standard effective concentration for hair dyeing while noting slow dermal absorption.
  2. 02 Toxicological modeling in animal subjects indicates an oral LD50 of 0.33 g/kg, though carcinogenic evidence remains limited for this specific triarylmethane.

Transparency

Not commonly dusted
Min. effective
0.1%
Red flag below
0.4%

As a colorant with known safety concerns and zero therapeutic benefit, any presence in skincare is typically for aesthetic purposes rather than skin health.


The Formula

Solubility
Water
Optimal pH 3 – 5
0 7 14

Stability

Highly stable in acidic environments but prone to precipitation when exposed to strong bases or high pH shifts.

Conflicts

  • Anionic surfactants (causes complexation)
  • Strong oxidizing agents
  • Sodium Hydroxide

Safety

CIR Status
Insufficient data
Max tested
0.4%
Sensitization risk Moderate

Explicitly banned for use in hair dyes in the EU (Annex II). Strictly regulated in Canada and California, with maximum limits of 0.2% in rinse-off products.


Your Skin

No Normal
No Dry
No Oily
No Sensitive
Irritancy Moderate
Comedogenicity Low

Our Assessment

Avoid

Basic Violet 4 offers no biological benefit to the skin and is subject to international bans, making it inappropriate for precision skincare.


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