Dispersing agents are the paint additives that keep wetted pigment particles apart after the mill has broken them down, and paint formulators choose them from 5 classes. Without them, a pigment dispersion flocculates again: color drifts, gloss falls and viscosity rises. The same additives appear as dispersants, wetting and dispersing additives or deflocculants, and British texts write their job as pigment stabilisation and colour stability.
The 5 classes are inorganic polyphosphates, polyacrylate dispersants, low-molecular-weight wetting and dispersing additives, polymeric dispersants and controlled-flocculating additives. Dispersing agents are one of the 15 families of paint additives, and this page covers how they work, one sourced level with its basis for each class (levels on pigment run from 0.3 % for polyacrylates to 150 % for carbon black with one polymeric grade), selection by paint type, the 3 substances with a page on this site, the 3 defects they prevent, the CLP, Ecolabel and VOC rules, the 4 test groups and how to request a grade.
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 Is a Dispersing Agent in Paint and Why Does Every Pigmented Paint Need One?#
A dispersing agent is a paint additive that stabilizes a pigment dispersion against flocculation, while a wetting additive speeds up the wetting of pigment agglomerates. One product can do both jobs, but no additive helps the mechanical breakdown of agglomerates, which is the work of the mill. Dispersant, deflocculant and wetting and dispersing additive are the three working names for the same family.
Every pigmented paint needs this stabilization because separated pigment particles re-associate into flocculates once nothing holds them apart. Flocculation shows in the finished paint as color drift, gloss loss and a rise in viscosity. The same loss of stability lies behind floating, flooding and settling, the other pigment defects of the wet film and the can.
The function is also a declared category in EU law. The EU Ecolabel criteria for paints, Decision (EU) 2025/2607, list "dispersing agent" among the ingredient functions that an applicant declares for each ingoing substance. Dispersing agents act on the pigments, one of the four other groups of paint raw materials beside binders, extenders and solvents or water. The share and role of each group are set out on paint raw materials.
Dispersant vs Surfactant: What Is the Difference?#
A dispersant is a surfactant or a polymer that anchors on a pigment and holds it apart from its neighbors, while a surfactant in the wider sense is any surface-active molecule, whether it wets, emulsifies or disperses. Low-molecular-weight dispersants are surfactants with one anchor group, and polymeric dispersants are polymers with many anchor groups and solvated chains.
All three surfactant roles share one side effect in paint. Emulsifiers, wetting agents and dispersants migrate to interfaces and stabilize foam through a surfactant-lined lamella, as Adams described in the Journal of Coatings Technology in 1998.
Substrate wetting is a different task: the paint must spread over the surface it is applied to, and that is a matter of surface tension rather than pigment stabilization. Substrate wetting, surface tension and the surfactant types used for them belong to wetting agents in paint, the sibling family of this page.
How Do Dispersants Work? Wetting, Breakdown and Stabilization#
Dispersants work on 2 of the 3 dispersion steps: wetting, where binder solution replaces air and moisture on the pigment, and stabilization against flocculation, while the mill alone performs mechanical breakdown by impact and shear.
The adsorbed molecule has two parts. Anchor groups adsorb on the pigment surface, and solvated chains that are compatible with the binder solution extend outward and keep the particles at a distance. Polymeric additives carry many anchor groups for adsorption on non-polar organic pigment surfaces.
Each pigment needs a definite amount of dispersant to reach this state. In the method of patent application US 2014/0316019 A1, dispersant is added stepwise to a pigment and extender slurry of about 70 wt % solids, viscosity is read with a Rotothinner ball rotor at 562 rpm, and the demand is the smallest amount that reaches the viscosity minimum, as wt % non-volatile dispersant on pigment plus extender. The demand curve and the grinding step are explained under pigment dispersion: wetting, grinding, stabilization and dispersant demand.
Electrostatic vs Steric Stabilization: Which Works Where?#
Electrostatic stabilization works essentially only in water and fails with multivalent ions or a high ion concentration, while steric stabilization works in waterborne and solventborne paint. Electrostatic dispersants charge the pigment surface and build an electrical double layer, described by DLVO theory, so that like-charged particles repel each other. Potassium, sodium and ammonium salts of polyacrylic acid are the standard electrostatic dispersants, and polyphosphate anions work the same way by raising the negative surface charge of pigments and extenders.
Steric stabilization does not depend on charge. The adsorbed, solvated polymer envelope physically prevents particles from approaching each other, in aqueous and non-aqueous systems alike, which is why solventborne paints rely on adsorbing additives. Electrosteric products combine both mechanisms, such as DISPERBYK-199, an aqueous modified styrene-maleic anhydride copolymer at 40 % non-volatile, and DISPERBYK-2010, described as steric plus electrostatic.
5 Types of Dispersing Agents for Paint Compared#
The 5 types of dispersing agents for paint are inorganic polyphosphates, polyacrylate dispersants, low-molecular-weight wetting and dispersing additives, polymeric dispersants and controlled-flocculating additives. The first two stabilize electrostatically in waterborne paint, the next two adsorb on the pigment, and the last deliberately bridges pigments into a loose network.
The table compares the 5 classes by chemistry, paint types, one sourced product level with its basis, strengths and limits.
| Class | Chemistry and members | Paint types | Example level (product, basis, source) | Strengths | Limits |
|---|---|---|---|---|---|
| Inorganic polyphosphates | Tetrapotassium pyrophosphate (TKPP), pentapotassium triphosphate (KTPP), sodium hexametaphosphate | Waterborne latex paint, distemper | KTPP in a 24 PVC acrylic semi-gloss (US 8,293,002 B2, Example 3): 0.60 % on pigment (0.14 % on total formula) | Sequester calcium and magnesium; prevent zinc oxide gelling | Electrostatic, aqueous only; virtually no wetting effect; affect dried films more than polyacrylates |
| Polyacrylate dispersants | Sodium, potassium or ammonium salts of polyacrylic acid and acid copolymers; hydrophobic copolymers | Latex paints, low-sheen to flat high-PVC latex | OROTAN 1620 (Dow product page): 0.3-1.0 % on pigment; TAMOL 165A (Dow product page): 0.6-1.0 % on pigment | Structure close to the binder, less effect on the dried film | No wetting properties; combined with a wetting agent |
| Low-molecular-weight wetting and dispersing additives | Fatty-acid based single-anchor surfactants (anionic, cationic, nonionic), phosphoric acid esters, alkylol ammonium salts, salts of polyamine amides, lecithin | Paints pigmented with inorganic pigments and TiO2 | DISPERBYK-111 (BYK product page): TiO2 1-3 %, inorganic 2.5-5 % as supplied on pigment, may accelerate acid-catalyzed baking systems; ANTI-TERRA-U (BYK product page): TiO2 0.5-1 %, inorganic 1-2 %, organic 1-5 % as supplied on pigment | Good on inorganic pigments | Weak on organic pigments and fine carbon black; high doses can harm hardness and water resistance |
| Polymeric dispersants | Polyether-modified styrene-maleic anhydride copolymers, other multi-anchor polymers, hyperdispersants (Solsperse 20000, 100 % active) | Waterborne and solventborne paints with organic pigments and carbon black | BYK guidance for polymeric additives: 1-10 % (inorganic) and 10-30 % (organic) as supplied on pigment; DISPERBYK-190 (BYK TDS): TiO2 10-12 %, organic 30-75 %, carbon black 130-150 % as supplied on pigment | Steric, works in both carriers, high doses tolerated | High dose on pigment |
| Controlled-flocculating additives | Low-molecular-weight additives with two to three or more separated anchor groups | Primer surfacers, fillers, intermediate coats | BYK-P 104 S (BYK product page): 0.5-2.5 % on TiO2, 3-10 % on inorganic and 10-20 % on organic pigment, as supplied on pigment | Anti-floating, anti-settling, anti-sag | Lower gloss; not for high-gloss topcoats |
Two classes have their own page, and three are sections of this hub. A polymeric dispersant is a wetting and dispersing additive with many anchor groups for adsorption on organic pigment surfaces and solvated chains for steric stabilization; hyperdispersants such as Solsperse 20000, a 100 % active polymeric dispersant, belong to this class. Polyacrylate dispersants are the polyacid salts of the electrostatic route, and their structure, close to that of the binder, explains why they affect the dried film less than polyphosphates do. Controlled-flocculating additives form a network of pigment bridges that low shear breaks, which gives pseudoplasticity, thixotropy and resistance to settling and sagging.
Why Do Single-Anchor and Multi-Anchor Additives Behave Differently?#
Single-anchor additives, which are fatty-acid based in many products and anionic, cationic or nonionic, stabilize inorganic pigments well but organic pigments and fine carbon black poorly, while multi-anchor polymeric additives adsorb on non-polar organic surfaces. Organic pigments and fine carbon black therefore take a polymeric wetting and dispersing agent, which also stabilizes them sterically in waterborne and solventborne paint alike.
Dose tolerance separates the two groups as well. High doses of low-molecular-weight additives can harm the hardness and water resistance of the film, while high doses of polymeric additives are better tolerated because they resemble the binder. The two BYK product pages show how far apart the doses lie: DISPERBYK-190, a polymeric grade, runs at 10-12 % as supplied on TiO2, while DISPERBYK-111, a low-molecular-weight phosphoric acid ester with an acid value of 129 mg KOH/g, runs at 1-3 % on TiO2.
How to Choose a Dispersing Agent by Paint Type#
Choose a dispersing agent by the paint's carrier first and its pigment second: a polyacrylate or polyphosphate for waterborne latex paint, an adsorbing low-molecular-weight or polymeric additive for solventborne paint, and a polymeric dispersant for organic pigments in either carrier.
The table matches 4 paint types to their carrier and main class, a published level with its basis, and the point to watch.
| Paint type | Carrier and main class | Example level (formulation, basis, source) | Watch-out |
|---|---|---|---|
| Emulsion (latex) paint formulation | Waterborne; polyacrylate plus polyphosphate | PCC EU Ecolabel indoor white guide formulation: EXOdis PC540i 0.6 + EXOdis PC185 0.2 % wt in the grind (designed against Decision 2014/312/EU, now repealed by Decision (EU) 2025/2607); US 8,293,002 B2 semi-gloss: TAMOL 731A 0.70 % active on pigment (0.67 % as supplied on total) with KTPP 0.60 % on pigment; distributor guide formulation (Raykem): 0.3-0.5 % of total batch | Zinc oxide needs a polyphosphate; HASE can displace an acid-copolymer dispersant |
| Distemper paint formulation | Waterborne; polyphosphates | See the distemper page | Sodium hexametaphosphate acts as dispersant and deflocculant for pigments and extenders |
| Epoxy paint formulation | Solventborne 2K, waterborne 2K and 1K epoxy ester | Heubach guide formulation 132-01 (solventborne 2K): ANTI-TERRA-204 0.50 pbw per 100 (% on total wet paint); Heubach waterborne 2K guide WB02_007: DISPERBYK-190 0.65 pbw per 100; Heubach epoxy-ester primer guide SB05_003: soya lecithin 0.25 + ANTI-TERRA-U 0.45 pbw per 100 | Electrostatic classes do not work in the solventborne systems |
| Polyurethane paint formulation | Solventborne 2K | Heubach guide formulation 687-03 (high-solids): ANTI-TERRA-204 0.15 pbw per 100 in the premix; Heubach guide formulation 732-11: ANTI-TERRA-204 0.55 pbw per 100 | Electrostatic classes do not work in the solventborne systems |
The published examples follow the carrier rule. Two of the three latex examples combine two dispersants, and the waterborne 2K epoxy uses a polymeric grade, while the solventborne 2K epoxy and polyurethane guide formulations dose one dispersant at 0.15 to 0.55 pbw per 100 parts of paint. The dispersant is one line of a full additive package, and each package is laid out on paint formulations by paint type.
Latex paint with zinc oxide as a mildewcide needs a polyphosphate to prevent gelling (Phosphate Forum of the Americas). Tetrapotassium pyrophosphate serves this purpose in interior and exterior latex paint, where it also deflocculates the pigment and gives stable viscosities, but it has virtually no wetting effect and is combined with a wetting agent.
When to Add a Dispersing Agent: Mill Base First, Late Addition Second#
In 2 published examples, the dispersant enters the liquid before the pigment. The PCC EU Ecolabel indoor white guide formulation starts with water, dispersants and defoamer, then adds pigments and fillers slowly, grinds and lets down. US 8,293,002 B2 lists water, hydroxyethyl cellulose, biocide, propylene glycol, polyacrylate dispersant, KTPP, surfactant, defoamer and amine before titanium dioxide and kaolin, then latex, water, HEUR and defoamer.
Both examples therefore put the dispersant and a defoamer into the liquid before the pigment, and both add the latex or binder and the thickener after it. Paint making as a whole runs from premix through dispersion to let-down and adjustment, and the stage where each additive goes in is explained under how paint is manufactured.
Complete Table of Dispersing Agent Substances Used in Paint#
The table lists all 3 dispersing agent substances with a page on this site, with CAS number, class, function in paint, an example level with basis and its source, and the CLP hazard line.
| Substance | CAS | Class | Function in paint | Example level (product, basis, source) | CLP hazard line |
|---|---|---|---|---|---|
| Tetrapotassium pyrophosphate (TKPP) in paint | 7320-34-5 (EC 230-785-7) | Inorganic polyphosphate | Dispersant for interior and exterior latex paint and tinting colorants; sequesters calcium and magnesium; prevents zinc oxide gelling | See the TKPP page; KTPP section (CAS 13845-36-8, EC 237-574-9): 0.60 % on pigment (0.14 % on total formula), US 8,293,002 B2, Example 3 | No Annex VI entry; ECHA C&L notified classification: H319 (Eye Irrit. 2, REACH joint submission, 92.16 %); KTPP: No Annex VI entry; ECHA C&L notified classification: not classified (REACH joint submission, 73.83 %) |
| Sodium hexametaphosphate (SHMP) in paint | 68915-31-1 (EC 272-808-3); also 10124-56-8 (EC 233-343-1) | Inorganic polyphosphate | Dispersant and deflocculant for pigments and extenders in emulsion paints and distempers; sequesters calcium and magnesium | See the sodium hexametaphosphate page | No Annex VI entry; majority of ECHA C&L notifications: not classified (91.25 %) |
| Lecithin (soya lecithin) in paint | 8002-43-5 (EC 232-307-2) | Low-molecular-weight wetting and dispersing aid | Natural amphiphilic wetting and dispersing aid; acetylated grade improves oil-stain cleanability of flat latex | Flat latex patent application US 2007/0212554 A1 (abandoned): 0.1-10 % on total paint composition, preferred 1.0-2.0 %; Heubach epoxy-ester primer guide SB05_003: 0.25 pbw per 100 | No Annex VI entry; ECHA C&L notified classification: not classified (99.75 %) |
| All other paint additive substances |
Pentapotassium triphosphate (KTPP, K5P3O10) has no page of its own and is covered on the TKPP page, while polyacrylates, phosphate esters and styrene-maleic anhydride copolymers are product chemistries of the class rows above rather than substance pages. TKPP has the formula K4P2O7 and a molar mass of 330.34 g/mol, and sodium hexametaphosphate carries two CAS numbers, 68915-31-1 for the polyphosphate and 10124-56-8 for the cyclic hexamer. Outside paint, sodium hexametaphosphate also serves as a sequestrant in water treatment and lecithin as a food ingredient.
Which Defects Do Dispersing Agents Prevent?#
Dispersing agents prevent 3 pigment-related paint defects: flocculation, floating and flooding, and settling, each by keeping pigment particles separated and equally mobile in the wet film.
The table links each defect to what the reader sees and the dispersant fix.
| Defect | What the reader sees | Dispersant fix |
|---|---|---|
| Pigment flocculation in paint | Color drift, gloss loss, viscosity rise; a color difference (delta E) between rubbed and unrubbed areas of the wet film | Dose at the ladder optimum; polymeric additives for organic pigments and carbon black |
| Floating and flooding | Benard cells and color separation in the drying film | Controlled-flocculating additives (some gloss loss) or polymeric deflocculation of all pigments, TiO2 included |
| Pigment settling in paint | Sediment in the can | Controlled flocculation gives a loose network that low shear breaks; the anti-settling class belongs to the rheology modifier family |
Floating and flooding start when solvent evaporation sets up density, temperature and surface-tension gradients and Benard-cell eddies that carry pigments of different mobility apart. This page uses the US terms: flooding is a uniform surface color, with a pigment concentration uniform on the surface but not through the film thickness (Journal of Coatings Technology and Research, 2004), and floating is the mottled Benard-cell pattern. Titanium dioxide must be stabilized as well as the colored pigments, or it separates from them.
The rub-up test diagnoses both flocculation and floating: the still-wet film is rubbed, and the color difference between the rubbed and the unrubbed area is the criterion. Dispersion covers 3 defects; all other defects and the additive families that prevent them are collected under paint defects.
How Are Dispersing Agents Regulated? CLP, REACH, Ecolabel and US Rules#
No dispersing agent substance in the table above carries a harmonized CLP classification: tetrapotassium pyrophosphate is notified as Eye Irrit. 2 H319, and sodium hexametaphosphate, KTPP and lecithin are notified by the majority as not classified. Polyacrylic acid and sodium polyacrylate (CAS 9003-01-4) have no Annex VI entry, and their classification is product-specific, so the supplier SDS decides. The regulatory load of the family sits in the EU Ecolabel ingredient rules and in the legacy status of APEO surfactants.
The table lists the instruments that reach dispersing agents, with their dates.
| Instrument and date | What it requires | Dispersing agents affected |
|---|---|---|
| CLP Regulation (EC) No 1272/2008, Annex VI | No Annex VI entry for any substance in the table; notified lines as in the substance table | TKPP, KTPP, sodium hexametaphosphate, lecithin; polyacrylates: see the supplier SDS |
| REACH registration (ECHA CHEM, read 2026-11-03) | Registration of substances placed on the EU market | TKPP and KTPP registered; no lecithin registration listed in ECHA CHEM |
| APEO-free surfactants and dispersants: REACH Candidate List and Annex XIV | Nonylphenol ethoxylates on the Candidate List since 2013-06-20; Annex XIV entry 43 (Regulation (EU) 2017/999), latest application date 2019-07-04, sunset date 2021-01-04 | Legacy APEO wetting and co-dispersing surfactants; OROTAN 165 (Dow product page) is made without intentionally added APEO; Dispex AA 4140 (BASF information sheet) is declared free of alkylphenol and APEO |
| EU Ecolabel for paints: Decision (EU) 2025/2607 of 2025-12-17, valid until 2032-12-31 | "Dispersing agent" declared as ingredient function; APEO and PFAS excluded regardless of amount (criterion 4.3(e), (f)); ingoing substances with Table 6 hazards restricted at 0.010 % w/w or more of the final product unless derogated | Every dispersant in an Ecolabel paint; surfactant derogation in the paragraph below |
| VOC in paint: Directive 2004/42/EC Art. 2(5); 40 CFR 51.100(s) | EU: organic compound with an initial boiling point of 250 °C (482 °F) or less at 101.3 kPa; US: federal definition with its exempt list | TKPP and sodium hexametaphosphate non-volatile, not VOC; lecithin non-volatile, fluid grades follow their carrier |
A dispersant grade counts toward a paint's VOC through its carrier, not its active part. TKPP is not a VOC under Directive 2004/42/EC or 40 CFR 51.100(s), and a solvent carrier counts in the EU when its initial boiling point is 250 °C or lower, and in the US unless it is on the federal exempt list.
The EU Ecolabel derogates surfactants classified H411, H412 or H413 up to 1.0 % w/w in transparent, semi-transparent, white or light-colored paints and up to 3.0 % w/w in other colors (Decision (EU) 2025/2607, Table 7), while H317 has no surfactant derogation. VOC, biocide, CLP label and restricted-substance rules across all families are collected on paint additive regulations.
Under the US Federal Insecticide, Fungicide, and Rodenticide Act, sodium hexametaphosphate is not a pesticide (EPA, 2016). For each further status of a grade, the supplier's safety data sheet is the document to read.
How Is Dispersant Performance Tested? Hegman Grind, Gloss, Viscosity and Scrub#
Dispersant performance is measured with 4 test groups: fineness of grind, gloss, viscosity of the mill base and the paint, and scrub resistance. Each group has a current ASTM or ISO designation, from ASTM D1210-05(2022) for the grind to ASTM D2486-17(2025) for scrub.
The table assigns each test group its standard and edition and what it shows for dispersants.
| Test group | Standard and edition | What it shows for dispersants |
|---|---|---|
| Fineness of grind (Hegman gauge) | ASTM D1210-05(2022); EN ISO 1524:2020 (all liquid paints except flake pigments) | Degree of dispersion after the grind; 0 Hegman = 100 µm (4 mils), 4 = 50 µm (2 mils), 8 = 0 µm |
| Gloss measurement | ASTM D523-25; ISO 2813 (20, 60 and 85 degree geometry) | Gloss development of the ladder series; haze read beside gloss |
| Paint viscosity: KU, ICI and Brookfield | ASTM D562-10(2023) for Krebs units (KU) | KU of the finished paint; the mill-base viscosity minimum marks dispersant demand |
| Scrub resistance | ASTM D2486-17(2025): Method A cycles to failure, Method B % of a reference paint in the same run | Film integrity; the dispersant dose has an optimum for scrub resistance |
BET- or oil-number-based dosage formulas are not reliable except for specific pigment types, so the optimum level comes from a ladder series judged on gloss, haze and rub-up delta E. Gloss, color and the remaining film properties each have their own method, described under paint test methods.
The Hegman scale reads in reverse to particle size: 0 Hegman stands for 100 µm (4 mils), 4 for 50 µm (2 mils) and 8 for 0 µm, so a higher number means a finer grind. Scrub resistance links the film back to the dispersant level, because the dispersant dose has an optimum for scrub resistance, as Palasz describes in Paint & Coatings Industry magazine.
Sourcing Dispersing Agents: Product Forms, Specifications and Quote Requests#
Dispersing agents are bought as powders and granules, 60 % solutions of TKPP, aqueous polymer solutions of 21 to 40 % solids, 100 % active products and solvent solutions. A request names the class or grade, the pigment and the level on pigment, the paint type, the annual volume, the packaging and the delivery country.
Product form changes the active content behind a level: DISPERBYK-180 and Solsperse 20000 are supplied at 100 % active, while ANTI-TERRA-U comes at 50 % non-volatile in xylene and isobutanol 8/1. 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 the PCC Ecolabel indoor white paint at 0.8 % dispersant (0.6 + 0.2 % wt) needs 8 t of dispersant products (calculated). A quote then depends on grade, pack size, volume and delivery country.
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, with wetting and dispersion agents among its segments. Producers and distributors, and how to qualify 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 Dispersing Agents Interact With Other Additive Families#
Dispersing agents interact with 4 other paint additive families: neutralizers, thickeners, defoamers and corrosion inhibitors. The 4 interactions are listed below.
- Neutralizers: AMP (2-amino-2-methyl-1-propanol) acts as a co-dispersant in the grind of waterborne paint; see neutralizing agents for waterborne paint.
- Thickeners: HASE can displace an acid-copolymer dispersant from the pigment surface and flocculate the paint, and HEUR with a polyacid dispersant can destabilize as well; see paint thickeners and rheology modifiers.
- Defoamers: dispersants belong to the surfactants that stabilize foam lamellae, which defoamers break; see paint defoamers.
- Corrosion inhibitors: 0.1 % AMP with 30 % less dispersant allowed 25 % less sodium nitrite at equal flash-rust resistance (Advancion industrial coatings brochure); see corrosion inhibitors for paint.
How Much Dispersant Does a Paint Contain?#
Dispersant levels depend on class, pigment and product, and no single level covers the family. BYK guidance for polymeric wetting and dispersing additives gives 1-10 % on inorganic and 10-30 % on organic pigments as supplied on pigment, the OROTAN 1620 product page (Dow) gives 0.3-1.0 % on pigment, and a distributor guide formulation from Raykem for an interior mid-sheen paint uses 0.3-0.5 % of total batch.
The basis changes the number for one and the same dose. In the US 8,293,002 B2 semi-gloss, 7.00 parts of a 25 % active polyacrylate dispersant on 250 parts pigment equal 0.70 % active on pigment, 2.80 % as supplied on pigment (calculated) and 0.67 % as supplied on total formula. Starting levels by additive type and the ladder method that refines them are explained under paint additive dosage.