Aminomethyl Propanol (AMP)

Overview

Aminomethyl propanol — commonly called AMP or AMP-95 (the 95% active concentration most suppliers sell) — is a clear, low-viscosity liquid with a mild amine odour. It’s the modern workhorse for pH adjustment and carbomer neutralization in cosmetics, increasingly replacing the older triethanolamine (TEA) in professional formulations.

Chemically, it’s 2-amino-2-methyl-1-propanol — a small, branched amino alcohol. Its compact molecular structure is what gives it an edge over TEA: AMP-neutralized carbomer gels are noticeably clearer, more transparent, and often have better long-term stability than TEA-neutralized ones. The gels also tend to feel lighter and less tacky on skin.

AMP is used across the industry in hair gels, clear serums, moisturizers, sunscreens, and any product that uses a carbomer or acrylate polymer as its thickening system. Its low required concentration (roughly half that of TEA for the same job) makes it economical despite a higher per-gram cost.

What it does in a formula

AMP serves two roles, both related to its basicity:

1. Carbomer/acrylate neutralization — converts acidic carbomer dispersions into thick, clear gels by raising pH into the 5.5-7 range where the polymer chains repel each other and swell. The resulting gels are clearer and more elegant than those made with TEA or NaOH.
2. General pH adjustment — raises the pH of any acidic formula. Useful for bringing vitamin C serums, AHA formulas, or other acidic products up to a target pH without the cloudiness that inorganic bases sometimes introduce.

Because of its small molecular size, AMP integrates quickly and evenly into formulas without localized over-neutralization (the lumps you sometimes get when adding NaOH too fast).

How to use

• Carbomer neutralization: Fully hydrate your carbomer in water first. Then add AMP drop by drop while stirring gently. Use approximately 0.3-0.5% AMP per 0.5% carbomer (varies by carbomer grade). Stop when pH reaches 5.5-6.5 and the gel is clear and thick.
• AMP-95 vs. AMP-100: Most suppliers sell AMP-95 (95% active in 5% water). If a recipe calls for “AMP,” assume AMP-95 unless stated otherwise.
• pH adjustment: Dilute AMP-95 to a 10% solution in water for easier drop-by-drop control. Pure AMP-95 is very concentrated — one drop can jump pH significantly.
• Phase: Add to the water phase at any temperature. Stable up to 80 C.
• Ratio rule of thumb: For every 1g of carbomer, you’ll need roughly 0.6-1g of AMP-95 to neutralize. Always verify with a pH meter.

Best for / Worst for

Best for: neutralizing carbomer and acrylate polymers (Carbopol, Aristoflex AVC, Sepimax ZEN), clear gel serums, lightweight moisturizers, sunscreen gels, hair styling gels, any formula where gel clarity matters.

Worst for: formulas that need pH below 5 (AMP will fight you), products marketed as “amine-free” (niche clean-beauty concern), anhydrous products (no water to dissolve in), formulas where you need very high pH (AMP is still a weak base — use NaOH for pH >9).

Common pitfalls

Adding too much. AMP is potent — a few drops overshoot can push pH to 8+ and thin out your carbomer gel. Always add gradually with a pH meter running. You can’t easily undo over-neutralization.

Confusing usage rates with TEA. Recipes designed for TEA use 2-3 times more neutralizer by weight. If you’re substituting AMP for TEA, use roughly half the amount (or just go by pH).

Not accounting for AMP-95 vs. pure AMP. AMP-95 is 95% active. If a recipe calls for “0.5% AMP,” they almost always mean AMP-95 as-is. Don’t overthink the math unless precision formulating.

Amine odour in light formulas. In very light products (mists, toners) at higher usage rates, you might detect a faint amine smell. Keep usage minimal and ensure fragrance or essential oils mask it if needed.

Assuming all polymers neutralize the same way. Different carbomer grades (940, 980, Ultrez 10, ETD 2020) have different neutralization curves. Two drops of AMP in Carbopol 940 gives a different result than in Ultrez 10. Always test.

Substitutes

• Triethanolamine (TEA) — older alternative, slightly less clear gels, higher usage rate needed.
• Sodium hydroxide (NaOH) — inorganic base, higher viscosity gels but less clear, risk of localized over-neutralization.
• L-Arginine — amino acid base, very gentle, but weak and expensive.
• Tromethamine (TRIS) — another organic base, similar clarity to AMP, sometimes used in pharmaceutical gels.
• Potassium hydroxide (KOH) — inorganic, similar profile to NaOH, softer gel feel.