Triethanolamine (TEA)

Overview

Triethanolamine — universally abbreviated as TEA — is a clear, viscous liquid with a mild ammonia-like odour. It’s one of the most widely used pH adjusters and carbomer neutralizers in cosmetics, found in everything from drugstore moisturizers to professional hair gels.

Chemically, TEA is a tertiary amine: three ethanol groups attached to a nitrogen atom. This structure makes it a weak organic base that raises pH when added to acidic solutions. Its most famous job in cosmetics is neutralizing carbomer (a polyacrylic acid polymer) — when you add TEA to a carbomer dispersion, the pH rises from around 3 to 5.5-7, and the polymer swells into a clear, thick gel. This one reaction is the basis of countless gel products.

TEA has been used in cosmetics for decades and has an extensive safety record. Regulatory bodies limit it to low concentrations (typically under 5%) and recommend avoiding it in formulas containing nitrosating agents (which could theoretically form nitrosamines). At normal cosmetic usage rates, it’s well-tolerated by most skin types.

What it does in a formula

TEA plays two functional roles:

1. pH adjustment — raises the pH of acidic formulations. Commonly used to bring a finished product into the skin-friendly range of 5-7 after adding acidic ingredients.
2. Carbomer neutralization — specifically converts carbomer dispersions from thin, acidic slurries into thick, clear gels. The TEA molecule is large enough to create a slightly different gel structure than sodium hydroxide does — TEA-neutralized carbomer gels tend to be clearer but slightly less viscous than NaOH-neutralized ones.

TEA also acts as a mild surfactant and can help emulsify fatty acids (stearic acid + TEA forms a soap-like emulsifier in situ), though this use has become less common with modern emulsifiers available.

How to use

• Carbomer neutralization: Add TEA drop by drop to a fully hydrated carbomer dispersion while stirring gently (not whipping — you’ll trap air). The gel thickens and clears within seconds. Use approximately 0.5-1 part TEA per 1 part carbomer by weight, but always adjust by pH meter. Target pH: 5.5-7.0.
• General pH adjustment: Add drop by drop until the desired pH is reached. Always measure with a calibrated pH meter or precise strips.
• In emulsions (stearic acid method): TEA at 1-2% combined with stearic acid at 3-5% forms an in-situ anionic emulsifier. This old-school technique gives lightweight, vanishing-cream textures.
• Add to: Water phase. TEA is fully water-soluble and can be added at any temperature.
• Storage: Keep the bottle sealed — TEA is hygroscopic and absorbs moisture from air. It also yellows over time with exposure to air.

Best for / Worst for

Best for: neutralizing carbomer gels, raising pH of acidic serums and toners, in-situ emulsification with stearic acid, clear gel products, hair gels, lightweight lotions.

Worst for: formulas intended for very sensitive or compromised skin (some people react to amines), leave-on products at high concentrations, formulas containing nitrosating agents, products where you need a very high pH (TEA is a weak base — NaOH is better for strong alkalinity).

Common pitfalls

Over-neutralizing. Adding too much TEA pushes pH above 7, which destabilizes the carbomer gel (it thins out) and can irritate skin. Add slowly, measure after every few drops.

Air incorporation. Stirring too vigorously during neutralization whips air into the gel. Stir gently and slowly — the gel will thicken regardless of stirring speed.

Yellowing. TEA oxidizes to a yellow-brown colour over time, especially in products exposed to light or stored warm. Use opaque packaging and add an antioxidant if shelf appearance matters.

Confusing with AMP. Aminomethyl propanol (AMP) does the same job as TEA but produces clearer gels and is used at lower concentrations. Many modern formulators prefer AMP, but recipes written for TEA need adjustment if you swap — the neutralization ratios differ.

Using in nitrosamine-risk formulas. Avoid combining TEA with ingredients that release nitrites (certain preservatives, DEA, MEA in some conditions). The risk is low at cosmetic levels, but good practice is to avoid the combination.

Substitutes

• Aminomethyl Propanol (AMP) — clearer gels, lower usage rate, increasingly preferred.
• Sodium hydroxide (NaOH) — inorganic base, different gel texture, higher viscosity with carbomers.
• Potassium hydroxide (KOH) — similar to NaOH, slightly softer gel feel.
• L-Arginine — amino acid base, gentler, but weaker and more expensive.
• Sodium bicarbonate — very mild base, not suitable for carbomer neutralization.