Urethane® 645 Durable Concrete Coating

A solvent-based aliphatic urethane concrete coating designed to repel chemicals and resist abrasion. Available in a clear or colored high-gloss finish. Use as a top coat to the Epoxy 325 primer.

  • Coverage Up to 350 square feet
  • Coats 1
  • VOC Content 335 g/L
  • Finish High-Gloss
  • Colors
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The Urethane 645 is a solvent-based, two-component urethane concrete coating designed to coat concrete floors combining the highest quality of aliphatic urethane components. The Urethane 645 provides incredible abrasion resistance, acid resistance and chemical resistance. Recommended for indoor areas with high risks of exposure to chemical spills, fuel, heavy equipment, extreme temperatures and any other potentially damaging situation the substrate may encounter. The Urethane 645 is also available in a California compliant version offering <100 g/L VOC.


Exceptional when used for:
  • Applications: A topcoat in garages, shop floors, warehouses, kennels
  • Substrates: Concrete
Not for use on:
  • For interior use only



  • Composition - 73% solids nanotechnology driven high-performance solvent based aliphatic urethane coating
  • Excellent hardness - provides a long service life without loss of flexibility
  • Excellent durability - provides a long service life
  • May be used as a top coat or a stand alone product


  • High strength, tenacious adhesion
  • Maintains a cleanable, attractive, hygienic surface, easily scrubbed and cleaned
  • Stops dusting and allows for easy cleaning
  • Protects substrates from chemical spills and corrosion, withstands heavy use
  • UV stable - long term color retention, fade resistant


  • Abrasion resistant and scratch resistant
  • Provides a tough color-fast finish on warehouse floors and auto repair shops
  • Hot tire pickup resistant
  • Use as a top coat with the Epoxy 325 base coat for extra protection

Urethane 645 Rises Above

Urethane 645 meets or exceeds the following tests:

  • ASTM D-1308: Chemical Resistance
  • ASTM D-3363: Film Hardness
  • ASTM D-4541: Pull-Off Strength
  • ASTM D-4060: Abrasion Resistance
  • ASTM D-2794: Impact Resistance
  • ASTM D-3359: Adhesion

Abrasion/Chemical Resistance Percentage Improvement vs. Control

Urethane 645
Sealer Product

Auxiliary Information

  • Technical Specs

    • Feature: Durable Coating
    • Chemistry: Aliphatic Urethane
    • Color: Clear, tile red, beige, medium gray, light gray, off white, white
    • Finish: High gloss
    • Category: Coating
    • Carrier: Solvent
    • Availability: 2 component kit
    • Packaging: 1.5 Gallon Kit, 3 Gallon Kit
    • Coverage: 350 sq. ft. per gallon at 3-5 mils wet film thickness
    • Interior/Exterior: Interior
    • Application Method: Roller/brush
    • Application Temperature: 55-90 degrees F with relative humidity below 75%
    • Number of Coats: 1
    • New Concrete: Yes, at least 28 days after being poured
    • Storage/Shelf Life: 1 Year
    • Clean up: Ketone solvents
    • VOC Content: 335 g/L
    • Hardness: Shore D 65
    • Impact Resistance: 160 in/lb
    • Abrasion Resistance: 20 mg
    • Adhesion: 350 psi
    • Viscosity: 400 cps
    • Primer: Epoxy 325

    CURE TIMES: (70F)

    • Pot Life – 1.5 - gallon volume: 2-4 hours
    • Tack Free (dry to touch): 3-5 hours
    • Recoat or Topcoat: 5-9 hours
    • Light Foot Traffic: 14-24 hours
    • Full Cure (Heavy Traffic): 3-5 days


    • 10% Sodium Hydroxide: Long Term Immersion
    • 10% Sulfuric: Short Term Immersion
    • 10% Hydrochloric Acid: Long Term Splash Spill
    • 20% Nitric Acid: Short Term Splash Spill
    • 50% Sodium Hydroxide: Short Term Immersion
    • Acetic Acid 5%: Short Term Immersion
    • Ethylene Glycol: Short Term Immersion
    • Gasoline: Short Term Immersion
    • Mek: Not Recommeded
    • Methyl Alcohol: Short Term Splash Spill
    • Xylene: Short Term Immersion
  • Preparation

    1. The concrete substrate to be coated must be clean, dry, and completely free of loose particles, grease, oil, or any substance that would interfere with proper bond.
    2. Surface and air temperatures must be at least 55°F during application. Surface and air temperatures should not exceed 90°F. Keep material from freezing.
    3. The surface-zone moisture content of the concrete should not exceed 4% wt. A test should be made to determine that the concrete has an appropriate vapor barrier. This can be done by placing a 4’X4’ plastic sheet on the substrate and taping down the edges. If after 24 hours, the substrate is still dry below the plastic sheet, then the substrate does not show signs of eventual hydrostatic pressure problems that may later cause disbanding.
    4. For a one or two coat thin build system (3-10 mils dry) we recommend either mechanical scarification or acid etching until a suitable profile is achieved. For a complete system build higher than 10 mils dry, we recommend a fine brush blast (shot blast). If acid is used to clean the concrete, neutralize the surface completely and rinse it with water prior to application. Then wait for the concrete to dry out for at least 24-48 hours.
  • Application


    This product comes pre-packaged by weight. Kits should be mixed in their entirety. This product has a two to one mix ratio by volume- merely mix two gallons of part A with 1 gallon part B. Urethane 645 A and Urethane 645 B should be thoroughly mixed before combining. Scrape the bottom and sides of each container. Urethane 645 A and Urethane 645 B can then be combined (Urethane 645 is sold as a pre-packaged kit and Urethane 645 Part A should be mixed in its entirety with Urethane 645 Part B). After the two parts are combined, mix well with slow speed mixing equipment such as a jiffy mixer until the material is thoroughly mixed and streak free. Avoid whipping air into the coating. Improper mixing may result in product failure.


    Test the sealer in an inconspicuous area to ensure the desired coverage and appearance is achieved. The mixed material can be applied by brush or roller. Workable time is about 3 hours. Maintain temperatures within the recommended ranges during the application and curing process. Properly prime the substrate with the Epoxy 325. It is best to maintain a wet edge to avoid roller marks. Direct sunlight or high temperatures may cause visible roller marking during application. Too thick of an application may result in product failure. Exposure to certain types of lighting such as sodium vapor lights may cause the product to discolor. Applications with relative humidity higher than 90% and/or poor air circulation may cause improper cure and surface tackiness. When the end of the pot life has been reached, you will find that the material becomes hard to apply and will actually tend to roll back up onto the roller. Do not try to continue application when the coating has reached this step. Applications made at different times with differing environmental conditions, may show slight variations in gloss. Coverage is approximately 350 sq. ft. per gallon. Make sure you test the surface for dryness prior to use and allow at least 14 hours before walking. A full cure will take up to 5 days to complete.


    Multiple coats of this product are acceptable. If you opt to recoat this product, you must first be sure that all of the solvents have evaporated from the coating during the curing process. It is best to test the coating before recoating or topcoating. This can be done by pressing on the coating with your thumb to verify that no fingerprint impression is left. If no impression is created, then the recoat can be started. Always remember that colder temperatures will require more cure time for the product before recoating can commence. Before recoating or topcoating, check the coating to insure no contaminants exist. If a blush or contaminants are present on a previous coat, remove with a standard detergent cleaner. When recoating this product with subsequent coats of the urethane, it is advisable to apply the recoat before 24 hours passes. Also, it is advisable to degloss the previous coat to ensure a trouble free bond.

  • Notes

    Application Notes:

    • Restrict the use of the floor to light traffic and non-harsh chemicals until the coating is fully cured. It is best to let the floor remain dry for the full cure cycle. Dependent on actual complete system application, surface may be slippery, especially when wet or contaminated; keep surface clean and dry.
    • Some cleaners may affect the color of the floor installed. Test each cleaner in a small area, utilizing your cleaning technique. If no ill effects are noted, you can continue to clean with the product and process tested.
    • Colors or clarity for clear may be affected by high humidity, low temperatures, or chemical exposure.
    • For best results use a high quality 3/8” nap roller.
    • Slab on grade requires moisture barrier.
    • Substrate temperature must be 5°F above dew point.
    • All new concrete must be cured for at least 28 days.
    • Colors may vary from batch to batch, therefore, use only product from the same batch for an entire job.
    • Improper mixing or too thick of an application may result in product failure.
    • Light or bright colors (white, etc.) may require multiple coats or a suitable color coordinated primer to achieve a satisfactory hide.
    • Tire contact may cause discoloration or staining.

    Clean Up

    Clean equipment, tools and surfaces with ketone solvent. Unused or old material may be disposed of in a waste disposal site in accordance with local, state and federal laws.


    Use appropriate safety equipment during application and handling. Please refer to the safety data sheet (SDS) for additional precautionary instructions before use.

    Best Performance

    • Proper application is the responsibility of the user.
    • Make sure the most current versions of technical data sheets and safety data sheets are being used.
    • Keep out of reach of children and pets.
    • Store in a cool, dry place away from direct sunlight. Avoid opened containers, as moisture will cure the material.


    350 square feet per gallon. Variations in texture and porosity of substrate will affect the coverage and performance of the product.

Product Comparisons

Uses Concrete Concrete
Chemistry Aliphatic Urethane Epoxy
Carrier Solvent Based Water Based
Finish High Gloss Semi Gloss
Color Clear, White, Off-White, Beige, Light Gray, Medium Gray, Red Clear, White, Off-White, Beige, Light Gray, Medium Gray, Red
Application Method Roller Roller
Drying Time (Full-Cure) 3-5 Days 2-7 Days
VOC Content 335 g/L 120 g/L