Coalescing agents are the paint additives that let the polymer particles of a latex (emulsion) paint fuse into a continuous film at the temperature it is applied, and formulators choose them from 6 classes. A coalescing agent, also called a coalescent or film-forming aid, lowers the minimum film formation temperature (MFFT) of the paint below the application temperature and then leaves the film or stays in it as a plasticizer. Its boiling point decides how it counts under VOC rules: TMPD-MIB boils at 254 °C (489 °F) and is no VOC under the EU Decopaint Directive, yet it is a VOC under US rules.
The 6 classes are ester alcohols, glycol ethers, low-VOC and non-fugitive coalescents, freeze-thaw glycols, open-time extenders and plasticizers. Coalescents are one of the 15 families of paint additives, and this page covers how they soften latex particles, which class suits which paint type and VOC limit, levels on 4 stated bases, all 15 coalescent substances with their EU VOC status and CLP hazard line, the 4 film defects coalescent choice decides, the VOC, CLP and REACH rules, 6 test groups and how to request quotes.
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 Coalescing Agents and Why Does Latex Paint Need Them?#
A coalescing agent is a paint additive that temporarily plasticizes the polymer particles of a latex (emulsion) paint, lowering their glass transition temperature (Tg) so the particles fuse into a continuous film at the application temperature. Patent US20210009844A1 defines coalescing aids by this temporary plasticization of emulsion polymers. The additive therefore works on the binder, not on the pigment or the water.
Latex paint needs the coalescent because its binder has a minimum film formation temperature (MFFT), the minimum temperature at which an emulsion vehicle coalesces into a continuous film in the scope of ASTM D2354-10(2023). The MFFT is directly related to Tg, and a higher coalescent level gives a lower Tg (Perera, Vanden Eynde and Borsus, Journal of Coatings Technology, 2001). In that study, a binder with an MFFT of 39 °C (102.2 °F) gave a paint MFFT of 12 °C (53.6 °F) with 6.5 % Lusolvan FBH on dry paint weight.
The paint trade uses 5 more names for the same additive: coalescent, coalescing aid, coalescing solvent, film-forming aid and temporary plasticizer. "Film forming agent" on this page means this paint additive, not the cosmetic or tablet-coating ingredient of the same name. Seven of the 15 coalescent substances below are glycol ethers that also serve as solvents, and solvents belong with binders, pigments and extenders among the paint raw materials that the additive package adjusts.
How Does a Coalescing Agent Work?#
A coalescing agent works by moving into the latex particles as water evaporates, lowering their Tg and the paint's minimum film formation temperature, and then leaving the film slowly or staying in it. The particles pack, deform and interdiffuse, and the coalescent softens them during deformation and interdiffusion.
Lowering the Tg also lowers the hardness of the film (patent US20210009844A1), so the speed at which the coalescent leaves decides how fast hardness returns. TMPD-MIB has a vapor pressure of 1.3 Pa at 20 °C, while DPnB, a P-series glycol ether, has 6 Pa at 20 °C, about 4.6 times as much, so DPnB leaves the film faster. Non-fugitive coalescents never leave: they stay in the film as plasticizer, cut VOC and need checks of dirt pick-up and block resistance (Mitchell, PCI, 2005).
In paint production, Texanol, the ester alcohol 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate (TMPD-MIB), is the hydrophobic, slow-evaporating coalescent: it partitions into the latex particles, lowers Tg and MFFT, and evaporates slowly so hardness and block resistance recover. Its solubility in water is 0.1 % at 20 °C, which keeps it in the particles rather than in the water phase. The MFFT itself is read on a temperature gradient bar, and the shift each additive causes is explained under minimum film formation temperature (MFFT).
Why Hydrophobic and Water-Miscible Coalescents Behave Differently#
Hydrophobic coalescents such as TMPD-MIB, DPnB and benzoates partition into the latex particles and lower MFFT efficiently, while water-miscible DPM, propylene glycol and butyl glycol stay in the water phase and serve open time and freeze-thaw (Mitchell, PCI, 2005). Water solubility orders the glycol ethers along this line. Propylene glycol phenyl ether (PPh) dissolves at 15.1 g/L at 20 °C and DPnB at 5 g/100 mL at 20 °C, while DPM and butyl glycol mix with water in all proportions.
The water-phase side of the package carries the larger VOC load. Glycol is present at 2 to 3 times the coalescent amount in a latex paint and is the largest VOC contributor (Mitchell, PCI, 2005). A switch from one particle-side coalescent to another therefore changes only part of a latex paint's VOC content, and the glycol share decides the rest.
6 Types of Coalescing Agents for Paint Compared#
The 6 types of coalescing agents for paint are ester alcohols, glycol ethers, low-VOC and non-fugitive coalescents, freeze-thaw glycols, open-time extenders and plasticizers. The first three lower the MFFT directly, freeze-thaw glycols and open-time extenders work in the water phase and the wet film, and plasticizers soften nitrocellulose lacquer and latex films.
The table compares the 6 classes by members, mechanism, one product or study level with its basis, strengths and limits.
| Class | Members | How it works | Example level (product or study, basis, source) | Strengths | Limits |
|---|---|---|---|---|---|
| Ester alcohols (hosted on this page) | Texanol (TMPD-MIB) | Hydrophobic; partitions into the particles; evaporates slowly | Texanol: 5.06 % on dry paint weight in an acrylic latex paint at pigment volume concentration 45 % (Perera et al., JCT, 2001) | Efficient MFFT reduction; hardness and block resistance recover | VOC under US rules; SVOC under the EU Ecolabel |
| Glycol ethers in paint | E-series: butyl glycol, butyl diglycol; P-series: PnP, PnB, DPM, DPnB, PPh | Water-miscible (butyl glycol, DPM) to partly hydrophobic (DPnB, PPh) | See the glycol ethers page | Open time, flow and wet edge; fast coalescence (PnB) | All 7 boil below 250 °C and count as EU VOCs; butyl diglycol is a US hazardous air pollutant |
| Low-VOC and zero-VOC coalescents | 2-ethylhexyl benzoate, TEG bis(2-ethylhexanoate), coalescing surfactants, reactive coalescents | Stay in the film as plasticizer or react with it | Surfynol AD01 and Dynol 360 (Evonik fact sheet): 0.1-1.0 % as supplied on total formula | Cut VOC; Velate 368 and Optifilm enhancer 400 rated High in latex (Eastman selector) | Dirt pick-up and block resistance checks; reactive types can yellow |
| Freeze-thaw stabilizers for latex paint | Propylene glycol, ethylene glycol | Depress the freezing point of the water phase; slow drying of the wet film | Glycol at 2 to 3 times the coalescent amount (Mitchell, PCI, 2005) | Freeze-thaw stability, open time | Largest VOC contributor of a latex paint |
| Open-time extenders and wet-edge additives | Wet-edge aids; butyl diglycol and propylene glycol also extend open time | Keep the wet film open for brush-in and repair | See the open-time extenders page | Brush-in and repair time | Open time is a major challenge in low- and zero-VOC paints (patent CN102652163A) |
| Plasticizers in paint and lacquer | TXIB, TEG bis(2-ethylhexanoate), polymeric azelate resins | Stay in the film and raise its flexibility | PARAPLEX RGA-2 and RGA-7 (Hallstar): 75-150 % on nitrocellulose dry weight | Lacquer flexibility; TXIB boils at 281 °C, above the EU VOC line | TXIB carries a registrant Repr. 2 H361 classification |
Dibutyl phthalate and chlorinated paraffins belong to the plasticizer class on this site only for their restrictions and replacements, and the regulation section below gives their status. TXIB, TEG bis(2-ethylhexanoate) and polymeric azelate plasticizing resins are the listed alternatives to dibutyl phthalate in nitrocellulose lacquer.
How to Choose a Coalescent for Each Paint Type#
Coalescent choice follows two limits, the VOC limit of the paint category and the MFFT of the latex: a conventional coalescent where the VOC limit leaves room for it, a low-VOC or non-fugitive one where it does not. The EU Decopaint category (a), "interior matt walls and ceilings", allows 30 g/L (0.25 lb/gal) ready to use for waterborne paint since 2010-01-01, and SCAQMD Rule 1113 (amended 2016-02-05) allows 50 g/L (0.42 lb/gal) less water and exempt compounds for flats and nonflats.
The table matches 4 paint types to their coalescent route, one sourced example and the point to watch.
| Paint type | Coalescent route | Example (basis, source) | Watch-out |
|---|---|---|---|
| Emulsion (latex) paint formulation, interior low-VOC | Ultra-low-VOC or non-fugitive coalescent in place of part or all of the conventional one | 50 g/L interior semi-gloss at equal loadings on resin solids (producer study, see below the table) | Lower hardness; dirt pick-up and block checks |
| Exterior emulsion paint on porous substrates | Hydrophobic coalescent dosed for the share the substrate absorbs | See the section on where the coalescent goes, below | Loss into fiber cement and other porous substrates |
| Water-based enamel paint formulation | Coalescent that leaves the film so hardness recovers | See the water-based enamel page | Blocking of soft films; non-fugitive types need block checks |
| Nitrocellulose lacquer formulation | Plasticizers: TXIB, TEG bis(2-ethylhexanoate), polymeric azelates | Eastman selector, lacquer efficiency: Optifilm enhancer 400 rating 3 of 3, TXIB rating 2 of 3 | Dibutyl phthalate needs an EU authorisation (Annex XIV entry 6) |
US rules leave no room for a non-VOC coalescent. TMPD-MIB is about 99.8 % volatile by EPA Method 24 (99.81 % in the test tables of patent US8106239B2), so nearly every gram counts toward the federal limits of 250 g/L (2.1 lb/gal) for flat and 380 g/L (3.2 lb/gal) for nonflat paint, less water and exempt compounds. Each paint type's full additive package, with the coalescent as one line of it, is set out in paint formulations by paint type.
In a BASF study of a 50 g/L interior semi-gloss at equal loadings on resin solids, the ultra-low-VOC coalescents gave higher gloss and in part better stain resistance but lower hardness than TMPD-MIB, while scrub resistance was unaffected. A low-VOC switch therefore trades hardness for VOC, and block resistance is the property to recheck.
How Much Coalescent Does a Latex Paint Contain?#
Coalescent levels are stated on 4 bases: % on total formula (wet), % on total solids, % on dry polymer and % on dry paint weight. Patent US8106239B2 puts coalescents at 0.1 to 10 % on total formula (wet) in its background statement and uses about 4.6 % on total solids of the paint in its Experiment 3.3. Patent US20210009844A1 claims 1 to 20 % on dry polymer, with narrower claimed ranges of 2 to 15, 3 to 10 and 2 to 8 %, and these are claim ranges, not a market norm.
In the 2001 study by Perera, Vanden Eynde and Borsus, an acrylic latex paint at a pigment volume concentration (PVC) of 45 % carries TMPD-MIB at 5.06 % on dry paint weight, the level given in the class table. The same gram of coalescent is a larger percentage of the dry paint than of the wet paint, so levels compare only on the same basis. Ladder studies that start from such a level and step it up and down are explained under paint additive dosage.
Where Does the Coalescent Go After Application?#
On fiber cement, 15.4 % of the TMPD-MIB in a test paint went into the substrate, 46.6 % evaporated and 37.9 % stayed in the film after one day (Perera, Vanden Eynde and Borsus, JCT, 2001). On glass, 53.4 % stayed in the film over the same day, so the porous substrate left the film 15.5 percentage points less coalescent (53.4 minus 37.9). All values are percentages of the coalescent in the wet paint.
Reactive coalescents take a third route: they are meant to crosslink into the film through an alkyd-like oxidative cure, which can cause yellowing, and there is little evidence of crosslinking that changes film properties (Mitchell, PCI, 2005).
Complete Table of Coalescent Substances Used in Paint#
The table lists all 15 coalescent substances with a page on this site, with CAS number, class, function in paint, EU VOC status by boiling point and the CLP hazard line.
| Substance | CAS | Class | Function in paint | EU VOC status (boiling point) | CLP hazard line |
|---|---|---|---|---|---|
| Texanol in paint | 25265-77-4 | Ester alcohol | Hydrophobic, slow-evaporating coalescent that lowers MFFT | Not a VOC, 254 °C (489 °F) | No Annex VI entry; ECHA C&L notified classification: not classified (REACH joint submission, 98.78 %, updated 2026-08-17) |
| Butyl glycol (EGBE) in paint | 111-76-2 | E-series glycol ether | Fast, water-miscible co-solvent and coalescing aid | VOC, 168.4-171 °C (335.1-339.8 °F) | Harmonized CLP Annex VI index 603-014-00-0 (ATP18, Delegated Regulation (EU) 2022/692, applicable since 2023-11-23): Acute Tox. 3 H331, Acute Tox. 4 H302, Skin Irrit. 2 H315, Eye Irrit. 2 H319 (Danger) |
| Butyl diglycol in paint | 112-34-5 | E-series glycol ether | Slow, water-miscible coalescent, flow and wet-edge aid | VOC, 230.4 °C (446.7 °F) | Harmonized CLP Annex VI index 603-096-00-8 (CLP00, applicable since 2010-12-01): Eye Irrit. 2 H319 (Warning) |
| Propylene glycol n-propyl ether (PnP) | 1569-01-3 | P-series glycol ether | Fast-evaporating co-solvent and coalescing aid | VOC, 150.2 °C (302.4 °F) | No Annex VI entry; ECHA C&L notified classification: Flam. Liq. 3 H226 (all major notifications); the REACH joint submission (23.49 %, updated 2025-10-24) adds Eye Irrit. 2 H319 |
| Propylene glycol n-butyl ether (PnB) | 5131-66-8 | P-series glycol ether | Fast-evaporating, partly hydrophobic coalescent and co-solvent | VOC, 171 °C (339.8 °F) | Harmonized CLP Annex VI index 603-052-00-8 (CLP00, applicable since 2010-12-01): Skin Irrit. 2 H315, Eye Irrit. 2 H319 (Warning) |
| Dipropylene glycol methyl ether (DPM) | 34590-94-8 | P-series glycol ether | Water-miscible co-solvent and hydrophilic coalescing aid | VOC, 188-190 °C (370.4-374 °F) | No Annex VI entry; ECHA C&L notified classification: not classified (REACH joint submission, 98.11 %) |
| Dipropylene glycol n-butyl ether (DPnB) | 29911-28-2 | P-series glycol ether | Slow-evaporating, fairly hydrophobic latex coalescent | VOC, 230 °C (446 °F) | No Annex VI entry; ECHA C&L notified classification: not classified (REACH joint submission, 79.71 %); also notified by a minority as Eye Irrit. 2 H319 (10.14 %) and Eye Dam. 1 H318 (5.84 %) |
| Propylene glycol phenyl ether (PPh) | 770-35-4 | P-series aromatic glycol ether | Slow-evaporating, efficient latex coalescent | VOC, 241.2 °C (466.2 °F) | No Annex VI entry; ECHA C&L notified classification: Eye Irrit. 2 H319 (REACH joint submission, 82.09 %) |
| 2-Ethylhexyl benzoate in paint | 5444-75-7 | Benzoate ester (low-VOC) | Low-odor, low-volatility latex coalescent | See the 2-ethylhexyl benzoate page | No Annex VI entry; ECHA C&L notified classification: Repr. 1B H360 (REACH joint submission, 36.82 %, updated 2021-09-09); also notified Aquatic Chronic 4 H413 (20 %) and not classified (20 %) by CLP notifiers |
| Triethylene glycol bis(2-ethylhexanoate) | 94-28-0 | Glycol diester (non-fugitive) | Ultra-low-VOC film-formation enhancer; lacquer plasticizer | See the TEG bis(2-ethylhexanoate) page | No Annex VI entry; ECHA C&L notified classification: not classified (REACH joint submission, 100 %, updated 2024-11-21) |
| Propylene glycol in paint | 57-55-6 | Glycol | Freeze-thaw stabilizer and open-time aid | VOC, 187.6 °C (369.7 °F) | No Annex VI entry; ECHA C&L notified classification: not classified (REACH joint submission, 98.24 %) |
| Ethylene glycol in paint | 107-21-1 | Glycol | Freeze-thaw stabilizer and open-time aid | VOC, 197 °C (386.6 °F) | Harmonized CLP Annex VI index 603-027-00-1 (CLP00, applicable since 2010-12-01): Acute Tox. 4* H302 (Warning); STOT RE 2 H373 is a REACH joint-submission self-classification (21.36 % of notifications), not harmonized |
| TXIB (TMPD diisobutyrate) in paint | 6846-50-0 | Glycol diester plasticizer | Non-VOC (EU) coalescent and lacquer plasticizer | Not a VOC, 281 °C (538 °F) | No Annex VI entry; not classified by the majority of CLP notifiers (54.12 %); the REACH joint submission classifies Repr. 2 H361 and Aquatic Chronic 3 H412 (29.77 %, updated 2025-12-18) |
| Dibutyl phthalate (DBP) in nitrocellulose lacquer | 84-74-2 | Phthalate plasticizer (legacy) | Former nitrocellulose lacquer plasticizer, replaced in the EU | See the dibutyl phthalate page | Harmonized CLP Annex VI index 607-318-00-4 (CLP00, applicable since 2010-12-01): Repr. 1B H360Df, Aquatic Acute 1 H400 (Danger) |
| Chlorinated paraffins (SCCP, MCCP, LCCP) in paint | 85535-84-8 (SCCP); 85535-85-9 (MCCP); 63449-39-8 (LCCP) | Chlorinated alkane plasticizers (legacy) | Covered for POPs, SVHC and replacement status | See the chlorinated paraffins page | MCCP: harmonized Annex VI index 602-095-00-X: Lact. H362, Aquatic Acute 1 H400, Aquatic Chronic 1 H410; SCCP: harmonized Annex VI index 602-080-00-8: Carc. 2 H351, H400, H410; LCCP: No Annex VI entry; ECHA C&L notified classification: not classified (89.7 %) |
| All other paint additive substances |
N-methyl-2-pyrrolidone (NMP, CAS 872-50-4) has no substance page here and appears among the restricted substances below. It carries the harmonized Annex VI entry 606-021-00-7 (Repr. 1B H360D, STOT SE 3 H335, Skin Irrit. 2 H315, Eye Irrit. 2 H319; ATP09, applicable since 2018-03-01), sits on the Candidate List since 2011-06-20 and is not in Annex XIV; REACH Annex XVII entry 71 (Regulation (EU) 2018/588) has barred it at 0.3 % or more since 2020-05-09 unless worker DNELs of 14.4 mg/m3 (inhalation) and 4.8 mg/kg/day (dermal) are met.
Which Film Defects Does Coalescent Choice Decide?#
Coalescent choice decides 4 film defects: poor film formation below the MFFT, short open time in low-VOC paints, blocking of soft films and surfactant leaching on fresh latex paint. The table gives the cause, the coalescent lever and the test for each.
| Defect | Cause | Coalescent lever | Test |
|---|---|---|---|
| Poor film formation below the MFFT | Paint applied below its MFFT, the minimum temperature at which it forms a continuous film | More coalescent or a more efficient one lowers Tg and MFFT | ASTM D2354-10(2023) |
| Short open time and wet edge | Reduced open time is a major challenge for low- and zero-VOC paints | Open-time extenders (class table, row 5) | ASTM D7488-11(2024) |
| Blocking in paint films | Lower Tg also lowers hardness; non-fugitive coalescents need block checks | A coalescent that leaves the film lets hardness and block resistance recover | ASTM D4946-89(2025) |
| Surfactant leaching on fresh latex paint | See the surfactant leaching page | See the surfactant leaching page | ASTM D7190-10(2023) |
Poor film formation and blocking pull the coalescent level in opposite directions. More coalescent lowers the MFFT, and the same lower Tg softens the film that must later resist blocking, so the coalescent that forms the film at the coldest application temperature also sets the block resistance of the dry paint.
Coalescent choice decides only these 4 defects. The other paint defects and the additives that prevent them are collected in one directory, from foaming and cratering to settling and yellowing.
How Are Coalescing Agents Regulated? VOC, CLP and REACH#
Coalescing agents are regulated first through VOC rules, which sort them by boiling point in the EU and by an exempt list in the US, and then through CLP classification, REACH restrictions and the US air-toxics list. Under Directive 2004/42/EC Art. 2(5), a VOC is any organic compound with an initial boiling point of 250 °C (482 °F) or less at 101.3 kPa. Under 40 CFR 51.100(s), no glycol, glycol ether, TMPD-MIB or TXIB is exempt (eCFR, 2026-10-30), and AIM compliance is calculated in g/L less water and exempt compounds.
The table lists the instruments that reach coalescents, with their dates.
| Instrument and date | What it requires | Coalescents affected |
|---|---|---|
| Decopaint Directive 2004/42/EC: Art. 2(5) and 2(6); Phase II limits from 2010-01-01 | VOC by initial boiling point at 101.3 kPa; limits in g/L of the ready-to-use paint, water included; reacting VOCs excluded | Every glycol and glycol ether in the substance table; not TMPD-MIB or TXIB |
| EU Ecolabel for paints: Decision (EU) 2025/2607, adopted 2025-12-17, valid to 2032-12-31 | SVOC band and SVOC limits; bar on ingoing H360 and H361 substances | TMPD-MIB and TXIB (SVOC); 2-ethylhexyl benzoate and TXIB (registrant classifications) |
| US VOC rules for paint: 40 CFR 51.100(s), 40 CFR 59 subpart D; SCAQMD Rule 1113, amended 2016-02-05 | VOC unless on the exempt list; limits in g/L less water and exempt compounds | Every glycol, glycol ether, TMPD-MIB and TXIB |
| CLP labeling of paints: CLP Annex VI and notified classifications; Annex I generic limits | Mixture classification from the ingredient classes and their concentration | Butyl glycol, butyl diglycol, PnB, ethylene glycol (harmonized); 2-ethylhexyl benzoate, TXIB, PPh (notified) |
| Restricted and banned substances in paint: REACH Annex XVII entries 54, 55 and 71; Annex XIV entry 6; Regulation (EU) 2019/1021 | Market restrictions, authorisation and the POPs ban | Butyl diglycol, DEGME, NMP, dibutyl phthalate, short-chain chlorinated paraffins |
| US Clean Air Act and TSCA: 40 CFR 63.62 and 63.63; TSCA Inventory | Glycol-ethers category of hazardous air pollutants; inventory listing | Butyl diglycol (HAP); all 13 glycol and ester coalescents (TSCA Inventory) |
| Calculate VOC in g/L with and without water: paint VOC content calculator; all rules: paint additive regulations |
The EU Ecolabel draws a second line at the same boiling point. Decision (EU) 2025/2607, which repeals 2014/312/EU, treats compounds boiling above 250 °C and below 370 °C (698 °F) at 101.3 kPa as SVOCs, so TMPD-MIB and TXIB count toward its SVOC limits. The same Decision bars ingoing substances classified Repr. 1A/1B H360 or Repr. 2 H361 at 0.010 % w/w or more of the final paint unless Table 7 grants a derogation. Decopaint Art. 2(6) adds the rule that reactive coalescents rely on: the mass of VOCs that react chemically during drying to form part of the coating is not part of the VOC content.
One coalescent can therefore be a VOC in one market and not in another, as TMPD-MIB shows at 254 °C. How each additive counts in each jurisdiction is set out under VOC in paint.
CLP classification of a paint follows its ingredients. Butyl glycol carries Acute Tox. 3 H331 and the signal word Danger since ATP18 applied on 2023-11-23. Registrants notify 2-ethylhexyl benzoate as Repr. 1B H360, so a paint with 0.3 % or more classifies as Repr. 1B if that classification is applied, and the REACH joint submission classifies TXIB Repr. 2 H361, which classifies a paint at 3 % or more (CLP Annex I Table 3.7.2). Eye Irrit. 2 glycol ethers such as butyl diglycol, PnB and PPh classify a paint only when the Eye Irrit. 2 ingredients add up to 10 % or more, unless Annex VI sets a specific concentration limit.
REACH restricts 3 glycol ether and solvent uses by Annex XVII entry (Regulation (EC) No 552/2009 and Regulation (EU) 2018/588). Entry 55 keeps butyl diglycol (DEGBE) at 3 % or more out of aerosol spray paints for the general public first placed on the market after 2010-06-27, and other consumer paints at 3 % or more must carry "Do not use in paint spraying equipment". Entry 54 bars a different glycol ether, DEGME (CAS 111-77-3), from general-public paints at 0.1 % or more after 2010-06-27, and entry 71 covers NMP. Dibutyl phthalate reached its Annex XIV sunset date on 2015-02-21, so an EU lacquer needs an authorisation to use it; it is on the Candidate List since 2008-10-28 and listed under California Proposition 65 since 2005-12-02. Short-chain chlorinated paraffins are listed in Stockholm Annex A by decision SC-8/11 (2017) and banned by Annex I Part A of Regulation (EU) 2019/1021, with a derogation below 1 % w/w in substances or mixtures; medium-chain chlorinated paraffins are on the Candidate List since 2021-07-08 and in Stockholm Annex A by decision SC-12/10 (2025). None of the 13 glycol and ester coalescents is on the Candidate List. In the US, butyl diglycol is a hazardous air pollutant in the glycol-ethers category (40 CFR 63.62), butyl glycol was deleted from that list in 2004 (40 CFR 63.63), and P-series glycol ethers fall outside the category.
How Is Coalescent Performance Tested?#
Coalescent performance is measured with 6 test groups: MFFT (ASTM D2354-10(2023)), freeze-thaw (ASTM D2243-20), open time (ASTM D7488-11(2024)), blocking (ASTM D4946-89(2025)), scrub (ASTM D2486-17(2025)) and VOC content (EPA Method 24 with ASTM D6886-24). The table assigns each group its current designation and what it shows for coalescents.
| Test group | Standard and edition | What it shows for coalescents |
|---|---|---|
| MFFT | ASTM D2354-10(2023) | Minimum temperature at which an emulsion vehicle forms a continuous film; scope limited to MFFT below 90 °C (194 °F); one patent reads it on a 76 µm (3 mil) drawdown over a gradient bar from -5 to 15 °C (23 to 59 °F) as the lowest temperature giving a clear, crack-free film |
| Paint storage stability and freeze-thaw tests | ASTM D2243-20 | Effect of freeze-thaw cycling on the viscosity and film of waterborne paint, the property glycols protect |
| Open time | ASTM D7488-11(2024) | How long a latex paint stays wet enough for brush-in and repair |
| Blocking | ASTM D4946-89(2025) | Blocking resistance of architectural paints, the cost of a soft film |
| Scrub resistance tests | ASTM D2486-17(2025) | Method A cycles to failure; Method B % of a reference paint in the same run; checks a coalescent change against wash resistance |
| VOC content testing of paint | EPA Method 24 (40 CFR 60 Appendix A-7); ASTM D6886-24, D2369-24, D3960-25 | Method 24 governs over formulation data (40 CFR 59.406(b)); D6886 measures individual VOCs in low-VOC paint by gas chromatography |
ASTM D6886-24 covers low-VOC air-dry coatings, is not for coatings that cure by chemical reaction, and states its precision for waterborne paint below 5 % VOC. ISO 2115 is the ISO method for the white point and MFFT of polymer dispersions. Every other paint test method is described under paint test methods.
Sourcing Coalescing Agents: Specifications and Quote Requests#
A request for a coalescing agent names the substance or class, the grade or a performance target (MFFT reduction, EU VOC status, boiling point), the paint type, the annual volume, the packaging and the delivery country. The boiling point at 101.3 kPa belongs in the specification, because it decides the EU VOC status of every substance in the table above.
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 1 % coalescent on total formula needs 10 t of coalescent (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)). Dibutyl phthalate and chlorinated paraffins are covered for replacement only, and TXIB, TEG bis(2-ethylhexanoate) and polymeric azelates are the listed alternatives for nitrocellulose lacquer. 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 Coalescents Interact With Thickeners and Surfactants#
Coalescents interact with 2 other paint additive families: thickeners, whose viscosity shifts with the coalescent, and wetting agents, to which coalescing surfactants belong. The 2 interactions are listed below.
- Thickeners: hydrophobic ester-alcohol coalescents raise the Brookfield viscosity of a HEUR paint, while propylene glycol and butyl diglycol lower it; see paint thickeners and rheology modifiers.
- Wetting agents: coalescing surfactants are surfactants that also lower the MFFT, so one additive serves both families; see wetting agents in paint.
Coalescing agents are also used in adhesives and sealants, a use this page does not cover.