Paint Additives: 15 Types, What Each Does, Dosage and How to Choose

Paint additives are the minor ingredients that a paint formulator adds to a liquid paint to control its flow, pigment dispersion, foam, drying, film formation, preservation, gloss and durability, and this reference sorts them into 15 families. They decide whether a latex paint (emulsion paint in British usage) stays stable in the can, whether an alkyd dries overnight, and whether the film resists mould, flash rust and UV light. Leveling, written levelling in British texts, is one of the properties they control. Add-ins that painters stir into a can of finished retail paint are a separate product category and stay outside this reference.

Six families act in the wet paint, three during drying and film formation, and six in the dry film. Together they make up about 1.8 % of the total formula in one published EU Ecolabel indoor white guide formulation. This page compares all 15 in one table, with an example level and its basis for each, matches them to 10 paint types, shows the five stages at which they enter the batch and the five bases in which their levels are written, and sets out the EU and US rules (VOC limits by jurisdiction, CLP thresholds such as 36 ppm for the EUH208 label of BIT), the anchor test of each family and the six fields a supplier request names.

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 Paint Additives?#

A paint additive is a substance added in small amounts to a paint's binder, pigment and solvent to give it a property the base formula lacks, such as stable viscosity, wetted pigment, fast drying or protection against microbes. The additive does not form the film, color it or carry it; it changes how the materials that do behave during storage, application and service.

Additives act in three phases of a paint's life. In the wet paint, rheology modifiers set viscosity and dispersing agents stabilize the ground pigment against flocculation. During drying, driers catalyze the oxidative drying of alkyds, and coalescents soften latex particles so they fuse into a film. In the dry film, biocides protect against microbes: EU law sorts them into in-can (PT6), film (PT7), wood (PT8) and antifouling (PT21) product types.

This reference covers additives for liquid paints: architectural and decorative paints, wood stains and varnishes, primers, industrial liquid paints, and road-marking and antifouling paints, both waterborne and solventborne. The phrase "paint and coating additives" means the same 15 families here, in their use in paint. Pigments, binders, extenders and solvents are raw materials, not additives, and appear only as the context in which an additive works.

What Share of a Liquid Paint Do Additives Make Up?#

Additives make up about 1.8 % of the total formula in the PCC EU Ecolabel indoor white guide formulation and 1.35 to 3.45 % of the total batch in a Raykem distributor guide for an interior mid-sheen emulsion paint. These two values are formulation examples, not a rule for every paint.

In the mid-sheen guide, the coalescent takes 0.5 to 1.5 % and the ASE/HASE thickener 0.3 to 0.8 % of the batch, so these two families supply more than half of the additive sum at both ends of the range (calculated). Both guides keep every single additive at or below 1.5 % of the batch, and everything else, from binder and pigment to extender and water, fills the remaining 96.55 to 98.2 % (calculated). A level in one guide is therefore a starting point for that binder and pigment set, and a different paint type moves it.

Where Do Additives Sit Among Binders, Pigments and Solvents?#

A paint has four groups of paint raw materials, binders, pigments, extenders and solvents, and additives are the fifth group that adjusts how the other four behave. Binders form the film, pigments give color and hiding, extenders fill volume, and water or solvent carries the mixture to the substrate. Each additive family targets one group or one interface: dispersants act on the pigment surface, coalescents and driers on the binder, and wetting agents and defoamers on the liquid surface.

The borders between the groups are narrow. A polyacrylate dispersant has a structure similar to a binder and affects the dried film less than a polyphosphate does (BYK wetting and dispersing guide). How the four other groups are chosen, and in which proportions, is set out under paint raw materials.

The 15 Types of Paint Additives Compared#

The 15 types of paint additives are rheology modifiers, dispersing agents, wetting agents, leveling agents, defoamers, neutralizers, driers, anti-skinning agents, coalescents, biocides, matting agents, corrosion inhibitors, light stabilizers, adhesion promoters and functional additives. The table compares their function, main chemistries, an example level with its basis and source, the paint carrier and the defect each prevents.

Catalysts and moisture scavengers sit under functional additives on this site, never as a 16th family. Moisture scavengers exist as a product category for two-component and moisture-cured one-component polyurethane paints, for example as a monofunctional isocyanate that removes water before it reacts with the hardener. Each example level in the table belongs to the named product, patent or label, and each family page gives the range of its products with their bases.

Which Additives Act in the Wet Paint?#

Six families act in the wet paint: rheology modifiers set viscosity, dispersing and wetting agents prepare pigment and substrate, leveling agents smooth the surface, defoamers remove air and neutralizers set the pH. Rheology modifiers control three shear regions: low shear in the can and on the wall (settling, sag and leveling, measured with a Brookfield viscometer), mid shear in stirring and loading (Krebs units, KU) and high shear under the brush, roller or spray gun (ICI cone and plate). Pigment dispersion runs in three steps, wetting, mechanical breakdown and stabilization; dispersing additives stabilize, wetting additives speed the first step, and no additive helps the mechanical breakdown, which is the work of the mill.

Wetting agents lower static and dynamic surface tension, so the paint spreads over the substrate instead of crawling back from it, and polyether-modified siloxanes serve as a fluorine-free alternative to fluorosurfactants. Leveling agents split into polyacrylates, which give long-wave leveling and anti-crater action in solventborne paint, and polyether-modified siloxanes, which reduce picture framing and fish eyes. Water-soluble surfactants carry a side effect: they can migrate to the surface of a fresh latex film, and ASTM D7190-10(2023) evaluates that leaching.

A defoamer works only if it enters the foam lamella and spreads on it, and both steps depend on the surface tension of the paint, the surface tension of the defoamer and their interfacial tension (Adams, JCT, 1998). Mineral-oil defoamers suit flat to medium-gloss acrylic, styrene-acrylic and vinyl emulsions but can cut gloss definition in medium to high gloss paints. Neutralizers raise the pH of waterborne paint and activate alkali-swellable thickeners. Their volatility decides what stays behind: ammonia boils at -33 °C (-27.4 °F), AMP at 165 °C (329 °F) and triethanolamine at 335 °C (635 °F), and amines with a high boiling point and a high pKa stay in the film and cause early water sensitivity and blocking. Residual dimethylethanolamine and triethylamine salts yellowed after 30 min at 120 °C (248 °F) in a PCI 2018 study by C. Li.

Which Additives Act During Drying and Film Formation?#

Driers catalyze the oxidative drying of alkyds, anti-skinning agents stop that reaction in the can, and coalescents lower the film formation temperature of latex so its particles fuse at the temperature of application. Driers are metal carboxylates of 2-ethylhexanoic (C8), neodecanoic (C10), isononanoic (C9) or natural acids, and the metal does the catalysis, so their level is written as % metal on resin solids. In waterborne paint, driers face incompatibility with the resin, hydrolysis or seeding, discoloration, poor initial dry and loss of dry with time. A zinc drier is claimed against wrinkling and orange peel in alkyds: Octa-Soligen Zinc 10 (Borchers product page) at 0.03-0.50 % Zn metal on binder solids.

Volatile ketoximes form temporary complexes with the drier metal, block its catalysis in the can and evaporate on application, while non-volatile antioxidants absorb radicals instead. The Danish EPA (2004) put methyl ethyl ketoxime (MEKO) at 0.3-0.7 % w/w of the total product in solventborne air-drying paint. Coalescing aids temporarily plasticize the emulsion polymer: they lower its glass transition temperature (Tg) and with it the hardness of the film until they evaporate. Permanent, or nonvolatile, coalescents remain in the dry film, and plasticizers serve the same purpose. A latex paint applied at or below its minimum film formation temperature shows poor coating integrity and appearance.

Which Additives Give the Dry Film Its Properties?#

Six families shape the dry film: biocides, matting agents, corrosion inhibitors, light stabilizers, adhesion promoters and functional additives preserve it, set its gloss, protect the metal beneath, resist UV, bond it and add missing properties. In-can preservatives protect the wet paint, including its cellulose ethers, which cellulase enzymes break down. Dry-film biocides such as IPBC, OIT, zinc pyrithione and terbutryn protect the applied film against mold and algae, and antifouling paints carry copper compounds with boosters such as copper pyrithione and zineb.

Matting agents lower gloss through fine particles at the film surface, from untreated and treated silicas and silica gels to micronized polyester and polymethylurea powder. Corrosion inhibitors work in four ways: flash-rust inhibitors protect bare steel under waterborne paint, inhibitive pigments such as zinc phosphate, molybdates and ion-exchanged silica passivate the metal, zinc dust protects it sacrificially, and micaceous iron oxide forms a barrier. Sodium nitrite, a flash-rust inhibitor, can form N-nitrosamines with secondary amines, so paints neutralized with amines take nitrite-free inhibitors.

Each dry-film family answers one group of paint defects, from mold and rust to gloss loss and delamination. Every defect, with the additive that prevents it, is listed under paint defects. A UV absorber filters the light before it reaches binder or wood, HALS trap the radicals that UV light creates in the film, and durable exterior wood protection needs HALS together with a UV absorber (PCI 2002 article). Silanes bond strongly to silica, glass and aluminum, slightly to steel and zinc and poorly to calcium carbonate, while a chlorinated polyolefin gives its best adhesion as a separate primer rather than as an additive.

How to Choose Paint Additives by Paint Type#

Choose paint additives by the paint's film-formation route first: latex paints need coalescents, neutralizers and an in-can preservative, air-drying alkyds need driers and an anti-skinning agent, and 2K epoxy and polyurethane guides add structure builders and anticorrosive pigment. The table matches 10 paint types to the families that define their package and one published guide value with its basis.

The guide values in the table share a pattern. The two-component epoxy and polyurethane primers use the same dispersant, organoclay and fumed silica, and the polyurethane adds a catalyst at let-down. The waterborne direct-to-metal primer replaces the zinc phosphate pigment with liquid corrosion inhibitors and thickens with two HEUR solutions (50 %) at 4 % and 0.1 % on total formula.

One guide value per paint type shows the defining family, while full paint formulations by paint type list every additive line with its stage. All ten packages are compared on paint formulations by paint type. A guide formulation fits its own binder and pigment set, so a formulator ladders its levels up and down before adopting them.

Waterborne Versus Solventborne: Which Families Change?#

Three families belong to one carrier: coalescents and neutralizers to waterborne paint, anti-skinning agents to solventborne paint; the other twelve change chemistry with the carrier. Coalescents exist for latex film formation and neutralizers set the pH of water-based systems, while the Danish EPA (2004) describes anti-skinning agents as additions to solventborne systems because waterborne systems are less prone to skinning.

The other families switch chemistry with the carrier. Cellulose ethers, HEUR and ASE/HASE thicken waterborne paint, while organoclays and organic thixotropes build structure in solventborne paint. Electrostatic stabilization of pigment works essentially only in water, while steric stabilization works in aqueous and non-aqueous paints, so solventborne dispersants rely on polymeric anchor-and-chain designs. Driers for waterborne alkyds are separate grades, shown in the enamel row of the table. Light stabilizers follow the same rule: an aqueous hydroxyphenyl triazine UV absorber dispersion, Tinuvin 479-DW ECO (BASF one-pager), carries about 20 % active.

Which Additives Does an Exterior Paint Need?#

An exterior paint adds a dry-film biocide, UV protection and water repellency to the interior package, for example IPBC at 1,600-4,800 ppm active outdoors (0.4-1.2 % of a 40 % product, EPA Reg. No. 5383-205). The same label sets 400-1,600 ppm active for interior paint in humid rooms (0.1-0.4 % of the product). The EU Ecolabel caps dry-film (PT7) actives at 0.50 % w/w of the final product for outdoor paint and 0.10 % w/w for indoor paint marketed for high-humidity rooms (Decision (EU) 2025/2607).

UV protection for exterior wood finishes takes the UV absorber and HALS levels given in the comparison table, on resin solids. Water repellency comes from functional hydrophobes, such as a polysiloxane emulsion added to silicone resin and silicate emulsion paints during or after production. Exterior here means the formulation of paint for outdoor exposure.

At Which Stage Is Each Additive Added?#

Each additive enters the batch at one of five stages, premix, grind, let-down, post-add or the second component, and a published US patent lists one latex semi-gloss sequence. US 8,293,002 B2 orders water, hydroxyethyl cellulose (HEC), biocide, propylene glycol, polyacrylate dispersant, pentapotassium triphosphate (KTPP), surfactant, defoamer and amine before the pigments titanium dioxide and kaolin, then latex, water, HEUR and defoamer.

The five stages are listed below, each with one published placement.

1. Premix: Disperse structure builders before the pigment; the Heubach 299-03 alkyd primer guide puts its self-activating organoclay (BENTONE SD-3, 0.40 pbw) and a calcium drier (0.10 pbw) into the premix.
2. Grind: Add defoamers as 100 % active compounds, which withstand high shear, because emulsion defoamers lose their power in a bead mill (Adams, JCT, 1998).
3. Let-down: Add the binder and the remaining liquid additives; in the same Heubach primer guide, the combination drier (1.20 pbw) and the anti-skinning agent (0.25 pbw) go in separately while stirring.
4. Post-add: Add preservatives at the end, as their labels instruct: a bronopol label (EPA Reg. No. 464-675) adds the product as the final step before packing, after any heating stage and below 40 °C (104 °F), and a dry-film blend label (EPA Reg. No. 5383-109) after the final pH adjustment.
5. Second component: Pack the hardener separately; in guide formulation 687-03 for a two-component polyurethane, the isocyanate forms component B while the catalyst enters component A at let-down.

How paint is manufactured decides where shear and heat fall in the process, and those two stresses set the defoamer form and the preservative timing. Premix, grind and let-down are explained step by step under how paint is manufactured.

Why Every Additive Level Needs a Basis#

A paint additive level means nothing without its basis, because one number can be a percentage of the wet paint, binder solids, pigment or metal on resin solids, or parts per million of active substance. The five bases are listed below with the family that uses each.

• % on total formula (wet, as supplied): most families, including the rheology, wetting, leveling and defoamer levels of the comparison table.
• % as supplied on pigment: dispersants, for which organic pigments take a higher range than inorganic ones.
• % metal on resin (binder) solids: driers, computed with the paint drier calculator.
• ppm active on total paint: biocides, from the label rate and the product's active content; 0.05-0.25 % of a 19.3 % BIT product equals about 97-483 ppm active (EPA Reg. No. 6836-423).
• % on binder solids: light stabilizers and every other additive whose source states it, such as the UV levels for exterior wood.

The two calculations behind these bases are exact arithmetic. As a worked example, 0.10 % of a 19.3 % BIT product gives 193 ppm active on the total paint (0.10 × 0.193 × 10,000). Drier weight equals the resin solids fraction times the % metal required times the batch weight, divided by the % metal of the drier solution, so a worked example of 1,000 kg of paint at 40 % resin solids, a 0.05 % cobalt target and a 12 % cobalt solution needs 0.40 × 0.05 × 1,000 / 12 = 1.67 kg of drier solution.

Paint additive dosage starts from such a level and moves by ladder studies, and US levels printed in lb per 100 US gal convert to g/L at 1 lb/gal = 119.8264 g/L. Starting levels by family, and how to ladder them, are collected under paint additive dosage.

How Are Paint Additives Regulated in the EU and US?#

Paint additives are regulated through the paint that contains them: VOC limits cap coalescents and glycols, CLP thresholds label preservatives and 2-ethylhexanoate driers, the EU Biocidal Products Regulation approves preservative actives, and REACH restricts siloxane residues and microparticles. The table lists the instruments, what each requires and the additives it reaches.

VOC limits never travel between jurisdictions, because their bases differ: Decopaint counts g/L of the ready-to-use paint with water included, while the US federal rule and SCAQMD count g/L less water and exempt compounds. The EU Ecolabel adds a second class: a compound boiling above 250 °C and below 370 °C (698 °F) at 101.3 kPa counts as a semi-volatile organic compound (SVOC), so Texanol, at 254 °C (489 °F), escapes the Decopaint VOC count but counts toward the Ecolabel SVOC limit of 25-30 g/L for category a, beside its VOC limit of 10 g/L. AMP shows the reverse case: it is exempt from the US federal VOC definition, yet it counts as a VOC under SCAQMD rules and the CARB 2019 suggested control measure.

Among paint additive regulations, CLP acts on sums: the entry for 2-ethylhexanoic acid and its salts (Annex VI 607-230-00-6, Repr. 1B H360D, set by ATP18, Delegated Regulation (EU) 2022/692, applicable since 2023-11-23) carries Note 12, added by ATP20 (Delegated Regulation (EU) 2023/1435) from 2025-02-01, so a paint is classified Repr. 1B when all 2-ethylhexanoates plus free acid add up to 0.3 % or more. Every label, biocide and restriction rule for the 15 families is detailed under paint additive regulations. REACH Annex XVII entry 30, Appendix 6, restricts such paints to professional users from 2023-12-01 (Regulation (EU) 2023/1132). Cobalt carboxylates are not substances of very high concern; the Candidate List names cobalt dichloride (since 2008-10-28) and cobalt sulfate, dinitrate, carbonate and di(acetate) (since 2010-12-15).

Legacy substances appear here only with their status and their replacement. Nonylphenol ethoxylates (NPE) sit on REACH Annex XIV as entry 43, sunset date 2021-01-04, and APEO-free surfactants replace them. UV-328 is listed in Annex I of the EU POPs Regulation by Delegated Regulation (EU) 2025/843, in force since 2025-08-04, so other UV absorbers take its place in EU paint. Lead driers meet the US limit of 16 CFR 1303.1 and the EU EUH201 label, and lead-free drier combinations replace them.

Which Tests Measure Additive Performance?#

Additive performance is measured with one anchor test per family, from Krebs-unit viscosity for rheology modifiers to salt spray for corrosion inhibitors, and the table gives the current ASTM or ISO edition of each test.

Paint test methods report in their own units: a Hegman reading of 0 equals 100 µm (4 mils) and 8 equals 0 µm, and no general conversion turns KU into mPa·s for a non-Newtonian paint. Each test, with its procedure and units, is described under paint test methods. Drying time, the anchor test for driers, follows ASTM D1640/D1640M-14(2022).

Sourcing Paint Additives: What a Specification Names#

A request for a paint additive names the family or substance, the grade or a performance target, the paint type, the annual volume, the packaging and the delivery country, the six fields of the quote form on this site. Prices depend on grade, pack size, volume and delivery country, and this site states none.

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 0.3 % HEC on total formula needs 3 t of HEC (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)).

Grand View Research estimates the paint additives market at USD 10.1 billion in 2025. Its estimate covers rheology modifiers, biocides, anti-foamers, wetting and dispersion agents and other additives, the segments that paint additive suppliers and manufacturers sell into. Producers and distributors, and how to source from them, are 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 Additive Families Interact in One Formula#

Additive families interact in one formula, so a change in one family shifts the dose of another, and four documented interactions are listed below.

• Neutralizer and dispersant: 0.1 % AMP with 30 % less dispersant allowed 25 % less sodium nitrite at equal flash-rust resistance (Advancion industrial coatings brochure).
• Surfactant and defoamer: surfactants stabilize foam lamellae, and zero-VOC paints need more surfactant, so defoamers that worked before no longer suffice.
• Thickener and preservative: liquid HEUR, HASE and ASE thickener grades contain in-can preservatives that count toward the paint's EUH208 calculation.
• Defoamer and leveling agent: a defoamer must be distinctly incompatible to reach the air interface, but incompatible substances cause fish eyes, craters and crawling.

Which Additive Terms Mean the Same Thing?#

The field uses eight synonym pairs for the 15 families, such as siccative for drier, flatting agent for matting agent and coalescing aid for coalescent. The other five pairs are thickener for rheology modifier, deflocculant for dispersing agent, anti-rust agent for corrosion inhibitor, pH adjuster for neutralizer and coupling agent for adhesion promoter.

Abbreviations clash as well: TEA stands for both triethanolamine and triethylamine, so a paint additive glossary writes each in full at first use. The remaining terms and abbreviations are listed in the paint additive glossary.