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1. Product Description

Durabak M26 is the military designation for the smooth-finish grade of Durabak, a single-component, moisture-cured polyurethane protective coating. It is the product referenced against MIL-PRF-32171B and is documented in a U.S. Navy ASTM F-718 application and test dossier, dated 2016-10-21. The M26 grade is supplied smooth (no recycled-rubber granules) for shipboard decks, equipment, and structures where a thick-film, abrasion-resistant, chemical-resistant polyurethane is specified.

M26 uses an MDI (aromatic) curative. It is NOT UV stable: the cured film ambers and fades with prolonged direct sunlight or UV exposure. For military surfaces in direct or sustained sun exposure (weather decks, exposed topside structures, vehicles), use Durabak-18 (aliphatic), which is covered by the Durabak-18 Outdoor Technical Data Sheet.

The coating cures by reaction with atmospheric moisture (releasing CO2). It is one part: no mixing, no catalyst, no induction time, and no plural-component or heated-line equipment. It bonds chemically to properly prepared steel, painted or sound-coated metal, aluminum, concrete, wood, fiberglass, rubber, most rigid plastics, and cured epoxy or primer. The cured film is flexible, waterproof, and bonds to itself for indefinite spot repair and recoat after light abrasion.

2. Recommended Uses / Features and Benefits

Recommended Uses

Smooth, thick-film protective coating for military, marine, and industrial service (interior, shaded, and submerged applications where UV stability is not required):

• Shipboard interior decks, passageways, and gangways
• Bilges, voids, tanks, and machinery spaces
• Military and tactical vehicle interiors, hulls, and undercoating
• Steel, aluminum, and concrete structures requiring abrasion and chemical resistance where UV exposure is not a factor
• Sealing and protecting corroded or pitted steel surfaces (prime bare steel)

Features and Benefits

• MIL-PRF-32171B / QPL. M26 is the smooth grade documented against MIL-PRF-32171B (current revision: B) and a Navy ASTM F-718 application/test dossier (see Section 8). Durabak M26 is QUALIFIED and listed on the Qualified Products List (QPL) under MIL-PRF-32171B.
• One-part system. No mixing and no catalyst. Reseal the can immediately after each pour.
• Moisture-cure. Cures with atmospheric moisture; higher relative humidity speeds cure. Avoid condensation or standing water on the surface before application.
• High-build film. Two coats deliver 29-39 mils dry total (per current Durabak Company datasheet), a thick protective film deposited in a single 1-part process without plural-component spray equipment.
• Abrasion resistance. 30.5 mg weight loss, Taber abraser, 1000 g load, 1000 cycles (ASTM D4060).
• Salt-water and chemical resistance. 100% salt-water resistance; salt spray no effect (ASTM B117 / D610); 7-day water immersion no effect (ASTM D1308). See the chemical-resistance table in Section 8.
• Flexibility. Elongation 497% (ASTM D2370); passes 1/8 inch mandrel bend with no cracking (ASTM D522). The cured film resists cracking and impact across a service temperature range of -60 F to +254 F.
• Repairability. Bonds to itself; spot-repair or recoat indefinitely after light abrasion, no removal of the existing film required.
• Fire test data. Flame spread index 01 (ASTM E-162); smoke generation 06 (ASTM E-662). Reported as tested values; not a fire rating.
• Low VOC. 250 g/L (2.08 lb/gal).

Note on slip resistance. The standard M26 grade is smooth and is NOT slip-rated. The published static coefficient-of-friction values (ASTM D1894 / ASTM D2047) apply to the textured (recycled-rubber granule) grade, not to the smooth M26. Where a non-skid deck profile is required, specify a textured Durabak grade or a separate non-skid system.

3. Product Data / Physical Properties

Property	M26 (MDI, Aromatic)	Test Method / Notes
Chemistry / binder	MDI aromatic polyurethane	NOT UV stable; ambers/fades in sun
Curative (isocyanate)	4,4'-MDI (101-68-8), <5.3%	MDI is a respiratory sensitizer; see Section 12
Ethylbenzene (constituent)	CAS 100-41-4, 5-10%	Constituent of the aromatic (xylene) solvent
Finish	Smooth (no granules)	M26 is supplied smooth
Components	1 (single-pack)	No mixing required
Cure mechanism	Moisture-cure (atmospheric)	Generates CO2 on cure
Liquid density	1.03 g/cm3 at 20 C	ASTM D1475; per Navy ASTM F-718 dossier
Weight (packaged)	approx. 10 lb/gal	Filled-can packaged weight (per current Durabak Company datasheet)
Viscosity	67-72 KU (Krebs)	Krebs Viscous Meter
Solids by weight	66%	per Navy ASTM F-718 / Durabak M26 Tests & Data
Solids by volume	75.8%	per current Durabak Company datasheet
VOC	250 g/L (2.08 lb/gal)	EPA Test Method 24
Flash point	27 C (80.6 F)	ASTM D56
Gloss (smooth)	approx. 84.7%	M26 smooth measurement
pH	approx. 8.0
Boiling point	140 C	Solvent fraction (xylene)
UV stability	NOT UV stable -- ambers/fades in sun	For UV/sun-exposed surfaces use Durabak-18 (aliphatic)
Service temp range	-60 F to +254 F	Freeze-thaw cycling; constant heat to 254 F
Shelf life	12 months (unopened)	Store 32-104 F, sealed

Solids by weight (66%) confirmed by the current Durabak Company datasheet and Navy ASTM F-718. Solids by volume: 75.8% per current Durabak Company datasheet.

Elongation: 497% (ASTM D2370); passes 1/8 inch mandrel bend with no cracking (ASTM D522). The cured film resists cracking and impact.

4. Surface Preparation

Surface must be clean, dry, and free of oil, grease, wax, dust, mildew, salts, and loose material. Adhesion fails on contaminated surfaces; solvent-wipe before mechanical prep if oils or mold-release agents are present.

Substrate	Minimum Preparation	Primer	Notes
Steel (bare or rusty)	Abrasive blast to SSPC-SP 10 (near-white) or SSPC-SP 11; 2-4 mil anchor profile (Testex Tape)	DuraPrime EP-90 2-part epoxy primer (approx. 70 sq ft/gal; VOC <=80 g/L)	Do not apply to bare steel without primer; zinc phosphate spray for rust-inhibitive touch-up
Painted/sound-coated metal	Scuff-sand all glossy surfaces; clean	Prime if coating is thin or questionable	Test adhesion on a small area first
Aluminum	Scuff-sand; degrease	Metcote etch primer (ivory, approx. 145 sq ft/qt)	30 min dry before overcoat at 77 F; heat resistant to 428 F
Concrete	Remove laitance; acid-etch or grind; verify dry (moisture-meter check)	Prime if porous or carbonated	Allow 30 days cure for new concrete
Wood	Sand to remove gloss; dry thoroughly	Prime if highly porous	Pressure-treated lumber: allow weathering; resin bleed prevents adhesion
Fiberglass	Sand to dull the surface; degrease	Primer optional; test adhesion	Mold-release wax must be fully removed
Rubber (sound)	Scuff-sand; degrease	Not required	Test adhesion first
Rigid plastics (general)	Scuff-sand; degrease	Test adhesion first	Not suitable for glass, marble, or polished stone
Polyethylene, polypropylene, and other low-surface-energy plastics	Standard abrasion will not bond; flame/plasma treatment or a dedicated adhesion promoter is required, and a test patch is essential.	Dedicated adhesion promoter required	Test patch is essential
Cured epoxy / primer	Light abrasion; clean	Not required	Good bond substrate
Glass, polished stone, or any non-scuffable surface	NOT SUITABLE	NOT SUITABLE	No mechanical key available; coating will not adhere

For Navy / military surface preparation, follow NAVSEA Standard Item 009-32 (surface preparation) and 009-26 (cleanliness) as applicable, verify soluble-salt contamination by the Bresle Patch Method, and confirm the prep grade and profile required by the specific MIL-PRF-32171B contract line.

5. Application

Environmental Conditions

All conditions must be met before and during application. Do not apply if any condition is out of range; cure and adhesion will be compromised.

Parameter	Required Range
Ambient air temperature	32 F to 95 F
Substrate temperature	45 F to 90 F
Dew-point rule	Substrate surface must be at least 5 F ABOVE the dew point
Relative humidity	Normal ambient humidity drives cure; avoid condensation or standing water on the surface
Substrate condition	Dry; no frost, ice, or surface moisture

Higher relative humidity accelerates cure. Application in hot, dry conditions lengthens dry-to-recoat time.

Mixing and Handling

Stir thoroughly before use and between coats. Do NOT shake the can; shaking entrains moisture and air, which can trigger premature surface cure and foam the film. Reseal the can immediately after each pour. Working/open time after opening the can is approximately 3 hr at 25 C (4 hr at 20 C, 6 hr at 10 C); the F-718 dossier labels this "pot life" although the product is one-part.

Application Tools

Method	Tool Specification	Best For
Roller (smooth)	3/16 in short-nap mohair varnish roller; approx. 1-1.5 gal per 9-in sleeve	Smooth M26 finish; standard application
Brush	Soft paint brush; apply two coats at right angles	Edges, cut-in, small areas
Airless spray	0.021-0.023 in tip; approx. 2.9 gpm class (e.g., Graco Bulldog 33:1); 90-100 psi inlet, approx. 3000 psi outlet	Large decks and structures; no heated lines, no plural-component equipment

Conventional spray is also acceptable. No heated lines and no plural-component equipment are required.

Coats and Dry Film Thickness (DFT)

Apply a minimum of two coats.

Variant	Wet Film per Coat	Dry Film per Coat	Total DFT (2 coats)	Measurement Standard
M26 (MDI, smooth)	17-25 mils	--	29-39 mils	Per current Durabak Company datasheet (primary)

Primary DFT: 29-39 mils total (2 coats) per current Durabak Company datasheet. Alternative measured value: 12-18 mils per coat; 24-35 mils total (Navy ASTM F-718, SSPC-PA 2). Confirm the DFT required by the specific MIL-PRF-32171B contract line.

Coverage

Variant	Coverage per Gallon	Coverage per Quart
M26 smooth	75 sq ft (at 2 coats)	18 sq ft

Coverage is practical coverage. Actual coverage varies with surface porosity, roughness, profile, and application technique.

Accelerator

An optional cure-accelerator additive is available. Use 1 packet per quart or 1 packet per gallon. The accelerator shortens cure time by up to 50% with no change to cured-film performance. Do not exceed the recommended dose.

6. Thinning / Reducer

Thinning is not normally required or recommended. If viscosity reduction is needed for spray application in cold conditions, use only an approved reducer:

Reducer	Notes
Solvide	VOC-exempt; approved for all 50 states including California and Utah; preferred reducer
Xylene / Xylol	Approved thinner; NOT sold to customers in California or Utah (the restriction is on the thinner product, not the Durabak coating itself)

Do NOT use generic lacquer thinner, acetone, MEK, or any unapproved solvent. Unapproved solvents alter viscosity unpredictably, can affect the moisture-cure reaction rate, and may void product performance data. Add reducer in small increments with stirring; over-thinning reduces DFT and solids deposition per coat.

7. Dry / Recoat / Cure Schedule

Times are approximate at 70-75 F and 50% relative humidity. Higher humidity and warmer temperatures shorten times; cooler temperatures and low humidity lengthen them. Schedule values are reconciled from the Navy ASTM F-718 dossier.

Stage	Time (typical conditions)	Notes
Tack / flash-off	1.5-3 hr	Surface dry to light touch; not yet ready to recoat
Touch dry	1.5-3 hr	Light-touch dry
Recoat window -- earliest	approx. 1 hr (light tack)	Apply second coat once first is touch-dry
Recoat window -- nominal	6-12 hr	Preferred window for full intercoat adhesion
Recoat window -- maximum	24 hr	Beyond 24 hr, abrade the surface before recoating to restore the bond
Walk-on / dry-to-handle	6-12 hr	Minimum before foot traffic
Full cure / return to full service	4 days (full cure; allow longer at cooler temperatures or low humidity)
Working / open time (per open can)	3 hr at 25 C	4 hr at 20 C; 6 hr at 10 C; reseal promptly

If the recoat window is missed (>24 hr), lightly sand with 80-120 grit, remove dust, and proceed. Do not skip this step; intercoat adhesion depends on it.

8. Performance and Test Data

M26 is the smooth grade documented against MIL-PRF-32171B and a U.S. Navy ASTM F-718 application and test dossier, dated 2016-10-21. The F-718 dossier is the source for the film-build, dry/recoat/cure, and application data in Sections 5 and 7. The F-718 reference chemistry is MDI (aromatic), confirmed by the 1.03 g/cm3 density in the dossier.

Physical Performance

Property	Result	Test Method
Abrasion resistance	30.5 mg weight loss	ASTM D4060 (Taber abraser, 1000 g load, 1000 cycles)
Salt spray resistance	No effect	ASTM B117 / D610
Salt-water resistance	100% salt-water resistance	Immersion; no effect
Water immersion (7-day)	No effect	ASTM D1308
Flame spread index	01	ASTM E-162
Smoke generation (specific optical density)	06	ASTM E-662
Flash point	27 C (80.6 F)	ASTM D56
Service temperature	-60 F to +254 F	Freeze-thaw cycling; constant heat to 254 F
Slip resistance (smooth M26)	Not slip-rated	Smooth finish; CoF values apply to textured grade only
UV / weathering	NOT UV stable -- ambers/fades in sun	For UV/sun-exposed military surfaces use Durabak-18 (aliphatic)

Note: fire test values are reported as tested results. They do not constitute a fire rating. Slip / traction coefficient-of-friction values (ASTM D1894: 0.95-0.98 dry / 1.41 wet; ASTM D2047: 1.21 dry / 0.67 wet) apply to the textured (recycled-rubber granule) grade and are NOT applicable to the smooth M26 product.

Chemical Resistance (7-Day Immersion)

Results from product manual 7-day immersion testing. Ratings: Excellent = no visible effect; Good = minor effect; Fair = moderate effect/check suitability; Poor = significant effect/not recommended.

Chemical	Rating (7-day immersion)
Potable water	Excellent
Salt water	Excellent
Dilute acids	Excellent-Good
Alkalis	Excellent-Good
Diesel fuel	Good
Gasoline	Fair
Acetone	Poor
Concentrated chlorine	Discolors if not rinsed off immediately

Concentrated industrial-strength chlorine will discolor the surface if left in contact. Rinse off immediately and use non-chlorinated cleaners for routine maintenance.

9. Clean-Up

Clean tools and equipment immediately after use. Cured Durabak is extremely difficult to remove.

Cleaner	Notes
Solvide	Preferred; VOC-exempt; 50-state legal
Xylene / Xylol	Effective; NOT sold to CA or UT (thinner restriction)

Dispose of solvent waste in accordance with local, state, and federal regulations. Do not pour solvent or coating residue into drains or waterways. Refer to the paired SDS for disposal guidance.

10. Storage and Shelf Life

Parameter	Specification
Shelf life (unopened)	12 months from date of manufacture
Storage temperature	32 F to 104 F
Storage condition	Sealed; dry area; away from heat, sparks, and open flame
Humidity	Keep moisture out of the can; reseal immediately after each use
Freeze	Do not allow to freeze

This is a moisture-cure product. Any exposure of the liquid to atmospheric moisture (open can, improperly resealed lid, humid storage) reduces working life and can cause surface skinning or gellation. Reseal the can immediately after each pour.

11. Packaging and Colors

Packaging

Size	Coverage (smooth, 2 coats)
Quart	18 sq ft
Gallon	75 sq ft

Standard Colors (Smooth, 15)

black, bright red, clear/colorless, cream, dark blue (vivid), dark grey, forest green, light blue, light grey, military olive, orange, sand, tan, white, yellow.

Military olive is the common military finish. Custom color matching is available at a 75-gallon minimum order with lead time. Colors are also hand-mixable by the user.

12. Limitations and Health / Safety

Limitations

• Not UV stable. M26 (MDI, aromatic) ambers and fades with prolonged direct sun or UV exposure. For sun-exposed military surfaces (weather decks, exposed topside structures, vehicles), use Durabak-18 (aliphatic), covered by the Durabak-18 Outdoor Technical Data Sheet.
• Smooth, not slip-rated. M26 is a smooth finish. Where a non-skid deck profile is required, specify a textured Durabak grade or a separate non-skid system.
• Not suitable for glass, marble, polished stone, or any surface that cannot be mechanically abraded to provide a key.
• Not certified or suitable for potable-water contact or potable-water submersion.
• Concentrated chlorine contact must be minimized; rinse off immediately to prevent discoloration.
• Recoating beyond the 24-hour maximum window requires mechanical abrasion before applying the next coat.
• Apply only within the temperature, dew-point, and humidity limits in Section 5.

VOC

VOC: 250 g/L (2.08 lb/gal). Sold in California. CARB SCM-compliant as an Industrial Maintenance coating at <=250 g/L VOC. NOT available in the SCAQMD (greater Los Angeles) district or other air districts that enforce a 100 g/L Industrial Maintenance limit.

Isocyanate / Respiratory Hazard

M26 contains 4,4'-diphenylmethane diisocyanate (MDI, CAS 101-68-8) at less than 5.3% by weight. MDI is a known respiratory sensitizer (GHS H334: may cause allergy or asthma symptoms or breathing difficulties if inhaled) and a suspected carcinogen (GHS H351). Repeated or high-level inhalation exposure may cause sensitization, after which even very low concentrations can trigger severe asthmatic reactions.

Ventilation and respiratory protection:

• Ensure adequate mechanical ventilation during application and until the coating is tack-dry.
• In confined spaces or enclosed areas (tanks, bilges, voids), use supplied-air respiratory protection (airline respirator or SCBA).
• For general brush/roller application in well-ventilated areas, a half-face respirator with organic-vapor / P100 combination cartridges is the minimum.
• MDI (4,4'-MDI, CAS 101-68-8) occupational exposure limits: OSHA PEL none established; ACGIH TLV 0.005 ppm (0.051 mg/m3) TWA; NIOSH REL 0.005 ppm TWA / 0.020 ppm ceiling.
• Spray application generates the highest inhalation exposure; supplied-air respiratory protection is mandatory for spray in any condition.
• Keep bystanders out of the application area until the coating is tack-dry.

Xylene (CAS 1330-20-7, 20-30% by weight) and ethylbenzene (CAS 100-41-4, 5-10%) are present. US occupational exposure limits:

Substance	OSHA PEL	ACGIH TLV
Xylene (1330-20-7)	100 ppm (435 mg/m3) TWA	100 ppm TWA / 150 ppm STEL
Ethylbenzene (100-41-4)	100 ppm (435 mg/m3) TWA	20 ppm TWA

Personal Protective Equipment (PPE)

Minimum PPE during application:

• Respiratory: Half-face respirator with organic-vapor / P100 cartridges for brush/roller in ventilated areas; supplied-air for spray or confined spaces.
• Skin: Chemical-resistant gloves (nitrile or neoprene); long sleeves.
• Eyes: Chemical splash goggles.
• Clothing: Remove and wash contaminated clothing before reuse.

California Proposition 65

WARNING: This product can expose you to ethylbenzene, which is known to the State of California to cause cancer. For more information go to www.P65Warnings.ca.gov.

Ethylbenzene (CAS 100-41-4) is the Prop 65-listed substance confirmed present in the current US SDS (rev 2020-04-24) as a constituent of the aromatic (xylene) solvent. DuraGrip anti-slip aggregate is silicon carbide (no crystalline silica); no crystalline silica Prop 65 warning is required.

Flammability

Flash point 27 C (80.6 F), ASTM D56. Classified Flammable Liquid, GHS Category 3 (H226). Keep away from heat, sparks, open flame, and hot surfaces. No smoking. Ground and bond metal containers during transfer. Extinguish with dry chemical, CO2, foam, or water fog. Do not use a direct water stream on burning liquid.

Additional Regulatory

• TSCA: All components are active or exempt on the US TSCA Inventory.
• Clean Air Act 112(b) HAPs: xylene and ethylbenzene are listed hazardous air pollutants.
• Clean Water Act: ethylbenzene is a Section 307 priority pollutant; xylene and ethylbenzene are Section 311 hazardous substances.
• SARA 302/304: No extremely hazardous substances present; reportable quantity not applicable.
• SARA 313: ethylbenzene (CAS 100-41-4) and xylene (CAS 1330-20-7) are listed toxic chemicals subject to supplier notification; applicable threshold reporting may apply.
• State right-to-know: xylene and ethylbenzene are listed under Massachusetts, New Jersey, New York, and Pennsylvania RTK programs.
• RCRA (waste disposal): If discarded as supplied (unused), this product exhibits the RCRA characteristic of ignitability, waste code D001 (flash point <60 C / 140 F, per 40 CFR 261.21). Unused xylene-bearing waste may also carry listed code U239 (xylene). Confirm the codes for your actual waste stream.
• US DOT (49 CFR): UN1263, PAINT, Class 3, Packing Group III. Limited quantity = inner packagings not exceeding 5 L (1.3 gal) per 49 CFR 173.150; consumer-quantity reliefs may apply to retail quart/gallon packaging.
• International inventories: all components listed or exempt on the inventories of Australia, Canada, China, Japan (CSCL), Republic of Korea, New Zealand, Philippines, Taiwan, EU/Eurasian (Russia), Vietnam, and United States.

Consult the paired Safety Data Sheet before use.

13. Supplier / Manufacturer

Durabak Bergenfield, NJ 07621, USA

Telephone: 303-690-7190

Emergency Telephone: 303-690-7190

Website: durabakcompany.com

14. Disclaimer / Warranty

The information in this Technical Data Sheet is based on tests and data believed to be accurate and is provided as a guide for proper product use. Values stated represent typical or average results; normal variations in application conditions, surface preparation, and film build will produce variations in performance.

The applicator is responsible for determining the suitability of this product for any specific application and for ensuring all applicable safety, regulatory, contractual (including MIL-PRF-32171B and the governing NAVSEA Standard Items), and environmental requirements are met. Durabak makes no warranty, express or implied, beyond the product specifications stated herein. No statement in this document shall be construed as a recommendation to infringe any patent.

Revision date: 2026-06-18

Version: 1.0