Neutralizing agents are the bases a formulator adds to a waterborne paint to set and hold its pH, in 5 types from ammonia and 2-amino-2-methyl-1-propanol (AMP) to dimethylethanolamine (DMEA), triethanolamine (TEA) and potassium or sodium hydroxide. They turn the acid groups of latex, dispersants and alkali-swellable thickeners into salts, so the thickener swells and the pigment stays dispersed. In British usage the additive is a neutraliser; the surface washes applied to walls before painting share the name but are not paint additives.
Neutralizers are one of the 15 families of paint additives, dosed at 0.1 to 2 % of the total formulation according to C. Li (PCI, 2018). This page compares the 5 types by boiling point and pKa, matches them to 4 paint types, and covers all 4 substances with a page here, the 4 defects they touch, EU and US rules, tests and sourcing.
How we check: regulations and classifications are read at the body that issues them, standards at the standards body, and every additive level names its basis and its source; the full method is in methodology and fact-checking.
What Are Neutralizing Agents in Paint and Why Does Waterborne Paint Need Them?#
A neutralizing agent is a paint additive that raises and buffers the pH of a waterborne paint, so the carboxyl groups of latex, dispersants and alkali-swellable thickeners are neutralized, the thickener swells and the pigment stays dispersed. AMP also co-disperses pigment and improves flash-rust resistance at low odor.
Waterborne paint needs a set pH because its raw materials arrive below the pH its additives work at. Palasz (PCI) lists acrylic latex binders at pH 6.5 to 8.5 and vinyl acetate latexes at pH 4.5 to 8.0 as supplied. Alkali-swellable thickeners stay insoluble until a base neutralizes their acid groups.
The family carries 3 working names. "pH adjuster" names the task, while "amine neutralizer" and "neutralizing amine" name the organic bases; ammonia and the inorganic hydroxides are neutralizers without being amines.
Which pH Values Do Published Waterborne Formulations Use?#
Published waterborne formulations end at pH 9.2 to 9.3 in the Advancion water-based acrylic direct-to-metal guide formulation, set with 15 % ammonia in the let-down and without a fixed ammonia level.
The additives in the paint set the lower edge of that window. Rheovis AS 1126 (BASF TDS), an alkali-swellable thickener, is kept at pH 7.5 or above, and BENTONE EW (Elementis TDS), a beneficiated smectite clay, is dispersed in water at pH 7.0 to 8.0 and stays stable from pH 6 to 11.
How Do Neutralizing Agents Work? Salt Formation, Volatility and Base Strength#
Neutralizing agents work by turning the acid groups of binders, dispersants and thickeners into salts; base strength (pKa) then sets how much base reaches the target pH, and boiling point sets whether it leaves the film.
Volatility splits neutralizers into fugitive and non-fugitive bases: ammonia is a weak base (pKa 9.25) that boils at -33.3 °C (-27.9 °F), evaporates as the film dries and leaves no amine behind. Triethanolamine sits at the other end: with a pKa of 7.74 and a boiling point of 335.4 °C (635.7 °F), at which it decomposes, it stays in the dry film. C. Li (PCI, 2018) reports that amines with a high boiling point, a high pKa and strong binding remain in the film and cause early water sensitivity and blocking. Pigment adsorption adds a third effect: in Advancion tests on titanium dioxide, 85 % of the added AMP adsorbed at 0.12 %, 34 % at 0.50 % and 21 % at 1.00 %.
5 Types of Neutralizing Agents for Paint Compared#
The 5 types of neutralizing agents for paint are ammonia, AMP, volatile tertiary amines such as DMEA, non-volatile alkanolamines such as triethanolamine, and the hydroxides KOH and NaOH; the first three leave the film, the last two stay.
The table compares the 5 types by boiling point and pKa from C. Li (PCI, 2018), paint types, one sourced example level with its basis, strengths and limits.
| Type | Members (bp °C / pKa, Li Table 10) | Paint types | Example level (product or formulation, basis, source) | Strengths | Limits |
|---|---|---|---|---|---|
| Ammonia | Aqueous ammonia, ammonium hydroxide (-33 / 9.25) | Latex wall paint, styrene-acrylic industrial latex, direct-to-metal let-down | Li Formula A (styrene-acrylic latex): about 0.21 % ammonia 28 % as supplied on total formula (wet), in the grind | Leaves the film; early water resistance and adhesion | Strong odor; poorer aged pH and viscosity stability than organic amines |
| Aminomethyl propanol (AMP) | 2-amino-2-methyl-1-propanol (165 / 9.8) | Latex and direct-to-metal paints | Advancion direct-to-metal guide formulation: 0.10-0.15 % on total formulation weight in the grind, with 30-50 % less primary dispersant | Co-disperses pigment; low odor; helps flash-rust resistance | EU VOC |
| Volatile tertiary amines | DMEA (135 / 9.31), triethylamine (89 / 10.7), DMAMP (160 / 10.2), etheramine DMMOPA (122 / 9.35) | Water-reducible acrylic, polyester and alkyd baking enamels | Li baking enamel: about 0.8 % active DMEA on total formula (wet), in the grind | Solubilize the resin; leave during baking; DMEA also blocks p-TSA acid catalysts | Heat yellowing of DMEA and triethylamine salts; slower low-temperature cure |
| Non-volatile alkanolamines | Triethanolamine (335 / 7.74) | General waterborne paint | See the triethanolamine page | Raises and buffers pH; not an EU VOC | Stays in the film (water sensitivity, blocking); Ecolabel SVOC; can degel a beneficiated smectite clay |
| Inorganic hydroxides | KOH, NaOH (non-volatile; not in Li Table 10) | CMIT/MIT-preserved latex paints | See the rheology modifiers page | Raise pH without the amine bases that speed CMIT degradation | Stay in the film; NaOH harmonized Skin Corr. 1A H314 |
The type sets two trade-offs at once. Ammonia gives early water resistance at the cost of odor and aged stability, while the amines trade odor for a VOC contribution or a film residue that grows with boiling point. DMAMP and DMMOPA appear in Li's comparison as alternatives to DMEA.
How to Choose a Neutralizing Agent by Paint Type#
Choose a neutralizing agent by how the film forms and cures: ammonia or AMP for air-drying latex and direct-to-metal paints, where the base must leave the film, and a volatile tertiary amine such as DMEA for baked water-reducible enamels.
The table matches 4 paint types to their neutralizer, a published example with its basis and the point to watch.
| Paint type | Neutralizer | Example (formulation, value, basis, source) | Watch-out |
|---|---|---|---|
| Emulsion (latex) paint formulation | Ammonia or AMP; NaOH where CMIT/MIT preserves the paint | Rheovis AS 1126 (BASF TDS): pH kept at 7.5 or above for the thickener | Amine bases speed CMIT degradation |
| Water-based direct-to-metal primer formulation | AMP in the grind, ammonia in the let-down | Advancion guide formulation: final pH 9.2-9.3 with ammonia (15 %) | Flash rust on bare steel |
| Waterborne industrial latex (styrene-acrylic) | Ammonia | Li Formula A: ammonia 28 % in the grind; 3B tape adhesion on cold-rolled steel at 7 days | Odor; aged pH and viscosity |
| Water-reducible baking enamel (polyester or acrylic polyol with melamine) | DMEA | Li: DMEA under-cures at 90-95 °C (194-203 °F) against a lower-boiling etheramine | Heat yellowing; slow low-temperature cure |
One paint can use two neutralizers, each at the stage where its job lies, as the direct-to-metal row of the table shows: AMP for co-dispersion, ammonia for the final pH. Each paint type's full additive package, with the neutralizer as one line of it, is set out in paint formulations by paint type.
Preservative and substrate narrow the choice further. CMIT/MIT degrades at high pH and faster with amine bases, so a CMIT-preserved paint takes sodium hydroxide rather than ammonia or triethanolamine. On bare steel, the neutralizer also has to suit the flash-rust inhibitor.
Where Published Formulations Add the Neutralizer: Grind or Let-Down#
Published formulations add the neutralizer in the grind (both formulations of C. Li and AMP in a direct-to-metal guide) or in the let-down (ammonia in the same guide). Each placement is that formulation's choice, not a general order of addition.
In the grind, AMP goes in before the pigments in the Advancion guide, ammonia 28 % in Li's styrene-acrylic Formula A, and DMEA in Li's baking enamel. The semi-gloss example of US 8,293,002 B2 lists an amine among the ingredients before titanium dioxide and kaolin. Premix, grind and let-down are the stages where each additive enters, and the full sequence is explained on how paint is manufactured.
Complete Table of Neutralizing Agent Substances Used in Paint#
The table lists all 4 neutralizing agent substances with a page on this site, with CAS number, type, function in paint, an example level with basis and its source, and the CLP hazard line.
| Substance | CAS | Type | Function in paint | Example level (product or formulation, basis, source) | CLP hazard line |
|---|---|---|---|---|---|
| Ammonia in paint | 1336-21-6 (aqueous solution); 7664-41-7 (anhydrous) | Ammonia | Fugitive neutralizer in the grind or let-down of latex paint | Li Formula A: about 0.21 % ammonia 28 % as supplied on total formula (wet) | Aqueous (Annex VI 007-001-01-2): Skin Corr. 1B H314, Aquatic Acute 1 H400, SCL STOT SE 3 H335 C >= 5 %, Note B; Danger |
| 2-Amino-2-methyl-1-propanol (AMP) in paint | 124-68-5 | AMP | Neutralizer and co-dispersant | Advancion direct-to-metal guide: 0.10-0.15 % on total formulation weight | Annex VI 603-070-00-6: Skin Irrit. 2 H315, Eye Irrit. 2 H319, Aquatic Chronic 3 H412; Warning |
| Dimethylethanolamine (DMEA) in paint | 108-01-0 | Volatile tertiary amine | Neutralizes and solubilizes water-reducible resins | Li baking enamel: about 0.8 % active on total formula (wet) | Annex VI 603-047-00-0: Flam. Liq. 3 H226, Acute Tox. 4* H332, Acute Tox. 4* H312, Acute Tox. 4* H302, Skin Corr. 1B H314; SCL STOT SE 3 H335 at C >= 5 %; Danger |
| Triethanolamine (TEA) in paint | 102-71-6 | Non-volatile alkanolamine | Raises and buffers pH; stays in the film | See the triethanolamine page | No Annex VI entry; ECHA C&L notified classification: not classified (majority); also notified by a minority (16.45 %): Eye Irrit. 2 H319 |
| All other paint additive substances |
The inorganic hydroxides have no page of their own. Sodium hydroxide (CAS 1310-73-2) carries Annex VI index 011-002-00-6, Skin Corr. 1A H314 at 5 % or more, with specific limits of Skin Corr. 1B from 2 % to below 5 % and Skin Irrit. 2 and Eye Irrit. 2 from 0.5 % to below 2 %; Danger. For potassium hydroxide (CAS 1310-58-3, EC 215-181-3), see the product SDS.
Which Paint Defects Do Neutralizing Agents Prevent or Cause?#
Neutralizing agents touch 4 paint defects: they prevent viscosity loss from pH drift and help against flash rust, and a wrong choice causes amine yellowing on heating or water sensitivity and blocking from base left in the film.
The table links each defect to the neutralizer's cause or role and the fix.
| Defect | Neutralizer cause or role | Fix |
|---|---|---|
| Viscosity loss in latex paint | pH drift below the activation pH of alkali-swellable (ASE and HASE) thickeners | Hold the pH with enough neutralizer |
| Amine yellowing | Residual DMEA and triethylamine salts on heating | Lower-yellowing amine, such as the etheramine DMMOPA in Li's test |
| Blocking in paint films | High-boiling, high-pKa amines left in the film; early water sensitivity | Fugitive base such as ammonia or AMP |
| Flash-rust inhibitors for waterborne paint | Advancion: 0.1 % AMP with 30 % less dispersant allowed 25 % less sodium nitrite at equal flash-rust resistance | Nitrite-free inhibitor where amine neutralizers are used |
| All paint defects and their additive fixes |
Amine yellowing comes from the salts that a residual amine forms in the film. In C. Li's comparison (PCI, 2018), the adipate salts of DMEA and triethylamine yellowed on heating while the salt of the etheramine DMMOPA stayed colorless. Triethylamine is abbreviated TEA in that article, so its result says nothing about triethanolamine, which shares the abbreviation.
A neutralizer can also break another additive. BENTONE EW (Elementis TDS), a beneficiated smectite clay, can lose its gel when triethanolamine is present.
How Are Neutralizing Agents Regulated? CLP Hazard Lines, VOC Status and US Rules#
Three of the 4 neutralizing agent substances with a page here carry a harmonized CLP Annex VI classification, AMP, aqueous ammonia and DMEA, while triethanolamine has no Annex VI entry.
The table lists the instruments that reach neutralizers, with their dates.
| Instrument and date | What it requires | Neutralizers affected |
|---|---|---|
| CLP labeling of paints: CLP Annex VI, consolidated version 2026-07-01 | Harmonized hazard lines; aqueous ammonia carries Note B (the label states the concentration) and STOT SE 3 H335 only at 5 % or more | AMP, aqueous ammonia, DMEA and NaOH; triethanolamine has no entry |
| VOC in paint: Directive 2004/42/EC Art. 2(4) and 2(5) | VOC = organic compound with an initial boiling point of 250 °C (482 °F) or less at 101.3 kPa | AMP and DMEA count; triethanolamine and ammonia do not |
| US VOC rules for paint: 40 CFR 51.100(s)(1) | Federal VOC definition with its list of excluded compounds | AMP excluded by 79 FR 17037, effective 2014-06-25; DMEA and triethanolamine not on the list |
| EU Ecolabel for paints: Decision (EU) 2025/2607, valid until 2032-12-31 | SVOC band above 250 °C and below 370 °C; cap on neutralizing agents with certain hazard classes | Triethanolamine counts as SVOC |
| REACH and US TSCA (checked 2026-10-27 to 2026-11-03) | Registration; TSCA Inventory listing | All 4 registered and on the TSCA Inventory; ammonia also on the EPCRA lists |
| California Proposition 65 (OEHHA list) | Warning for listed chemicals | Ammonia, DMEA and triethanolamine not listed (OEHHA list read 2026-11-03 and 2026-10-23) |
VOC status splits the 4 substances by jurisdiction. Ammonia contains no carbon, so it is not an organic compound under Directive 2004/42/EC Art. 2(4) and falls outside the US definition. 2-Amino-2-methyl-1-propanol (AMP) is excluded from the US federal VOC definition by 40 CFR 51.100(s), effective 2014-06-25 (79 FR 17037, published 2014-03-27), but its boiling point of 165 °C (329 °F) makes it a VOC in the EU. DMEA (134.1 °C, 273.4 °F) counts in both jurisdictions, while triethanolamine counts only under the US federal definition.
The EU Ecolabel adds its own limits. Decision (EU) 2025/2607 of 2025-12-17, which repeals Decision 2014/312/EU, treats compounds boiling above 250 °C and below 370 °C (698 °F) at 101.3 kPa as SVOCs and caps neutralizing agents classified H301, H311, H331 or for aquatic hazards at 0.50 % w/w of the final product, or 1.0 % in varnishes. VOC, biocide, CLP label and restricted-substance rules for every family are collected under paint additive regulations.
All 4 substances are REACH registered, and none is on the Candidate List, in Annex XIV, in a substance-specific Annex XVII entry or an EU POP (checked 2026-10-27 to 2026-11-03). For ammonia, NIOSH sets a REL of 25 ppm (18 mg/m3) TWA and 35 ppm (27 mg/m3) short-term, OSHA a PEL of 50 ppm (35 mg/m3) TWA, and the IDLH is 300 ppm.
How Is Neutralizer Performance Tested? pH, Viscosity, Storage and Adhesion#
Neutralizer performance is measured with 4 test groups: viscosity, package stability, tape adhesion and VOC content, because the neutralizer moves the thickener response, the aged pH, the early adhesion and the VOC figure of a paint.
The table assigns each test group its current designation and what it shows for neutralizers.
| Test group | Standard and edition | What it shows for neutralizers |
|---|---|---|
| Paint viscosity: KU, ICI and Brookfield | ASTM D562-10(2023) (KU, load to turn the paddle at 200 r/min); ASTM D2196-20(2026) (low-shear rotational) | Thickener response to pH; viscosity drift in storage |
| Paint storage stability tests | ASTM D1849-95(2019) (package stability); ASTM D869-21 (settling) | Aged pH and viscosity by neutralizer |
| Paint adhesion testing | ASTM D3359-23 (Method A X-cut, Method B lattice, ratings 5B to 0B) | Early adhesion of fugitive versus film-retained bases |
| VOC content testing of paint | EPA Method 24, the US reference method under 40 CFR 59.406 | Whether an amine adds to the VOC figure |
Viscosity tests read the neutralizer indirectly, because ASE and HASE thickeners respond to pH, so KU and Brookfield values show whether the neutralizer has brought the thickener to its working pH. Every other paint test method is described under paint test methods.
Sourcing Neutralizing Agents: Product Forms, Specifications and Quote Requests#
Neutralizing agents are bought as aqueous ammonia solutions, AMP with 5 % added water and other dilutions, and a 99 % DMEA grade. A request names the substance, its concentration, the paint type, the annual volume, the packaging and the delivery country.
Product form sets the concentration the specification names. Advancion, formerly ANGUS Chemical Company, sells AMP-95, AMP-90, AMP-75, AMP Regular and AMP Ultra PC, and lists for AMP-95 a flash point of 86 °C (187 °F), a density of 0.93 g/mL at 20 °C and a pH of 11.7 in 1 % solution. BASF sells N,N-Dimethylethanolamine S (DMEOA) as a 99 % grade.
Annual volume follows from the paint output: product mass equals paint output times level divided by 100, so a worked example of 1,000 t of paint at 0.15 % AMP on total formula needs 1.5 t of AMP (calculated). US suppliers deliver an English safety data sheet of 16 sections with the initial shipment and after an update (29 CFR 1910.1200(g)), and ammonia is also on the EPCRA Extremely Hazardous Substance and TRI lists. Sourcing and qualifying producers and distributors is covered on paint additive suppliers and manufacturers.
Two related pages cover regional sourcing and the market.
- Producers and distributors in India: paint additive manufacturers in India
- Market size, segments and leading producers: paint additives market
How Neutralizers Interact With Other Additive Families#
Neutralizers interact with 4 other paint additive families: they activate alkali-swellable thickeners, co-disperse with dispersants, limit the pH window of CMIT preservatives and decide which flash-rust inhibitor is safe. The 4 interactions are listed below.
- Rheology modifiers: ASE and HASE thickeners swell only once a base such as ammonia or AMP neutralizes their acid groups; see paint thickeners and rheology modifiers.
- Dispersants: AMP co-disperses pigment in the grind; see dispersing agents for paint.
- Biocides: amine bases speed the breakdown of CMIT at high pH; see paint biocides.
- Corrosion inhibitors: sodium nitrite can form N-nitrosamines with secondary amines, so nitrite-free inhibitors suit paints with amine neutralizers; see corrosion inhibitors for paint.
How Much Neutralizer Does a Paint Contain?#
Neutralizer levels depend on type and formulation: C. Li (PCI, 2018) puts pH neutralizers at 0.1 to 2 % of the total formulation, and the Advancion direct-to-metal guide formulation uses AMP at 0.10 to 0.15 % on total formulation weight.
The basis changes the number. Li's Formula A uses about 0.21 % ammonia 28 % as supplied, which is about 0.06 % NH3 on the total formula. Ladder studies that start from such a level and step it up and down are explained under paint additive dosage.