Altex Epoxy Barrier Undercoat - 4 Litre

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Altex Yacht & Boat Paint Epoxy Barrier Undercoat is a high performance, sandable epoxy high build coating which is both very corrosion and water resistant.

Epoxy Barrier Undercoat is recommended for:

  • Topside & Superstructure final sealing to provide an optimum surface for finish coating
  • As a high build surfacer to remove defects and achieve a finish suitable for application of Altex Polyurethane Undercoat or one of the Elite Polyurethane finish coats
  • As a high build barrier coat for below waterline application, used as part of an Altex Antifouling system
  • Direct application to sanded GRP, epoxy laminated wood and epoxy sealed wood
  • Direct application to epoxy faired surfaces
  • Application over Altex Epoxy Primer or Altex High Build Surfacer
  • Priming / undercoating over degreased & sanded aged polyurethanes, epoxies, fairing systems, gelcoats, epoxy laminates & fibreglass



  • Excellent build properties up to 150µm DFT in a two pass application
  • Excellent surfacing and sanding properties
  • Very good corrosion protection
  • Wide maximum self re-coat times for easy project management
  • Very good water and chemical resistance
  • Epoxy Barrier Undercoat may be top-coated with both acrylic or polyester urethane finishes and is especially formulated as an undercoat or sealer under the Altex Elite® range of polyurethane finish coats
  • May be used as a high build surfacer / undercoat for topcoating with Altex Polyurethane Undercoat
  • May be used in immersion service as part of an Altex Yacht & Boat recommended system


  • Colour: Off-White
  • Mix Ratio: 4 to 1 by volume
  • Thinner: Spray: Altex Thinning Solvent #12
  • Brush/Roller: Altex Thinning Solvent #22
  • Pot Life: 8 hours at 25°C
  • Induction Time: 15 minutes.  
  • Theoretical Coverage Rate: 4.5 sq meters per litre at 100 microns dry
  • Recommended Film Thickness Per Coat: 225-335 microns wet to obtain 100-150* microns dry (*applied in two passes)
  • Application: Air or airless spray, brush or roller
  • Dry Times (25°C / 100 µm DFT / 50% RH): Touch Dry: 90 mins. Dry to Sand: 6 hours

Recommended Recoat:

  • Min. Self Recoat: 30 – 60 mins between passes. 6 hours between coats
  • Max. Self Recoat: 5 days without sanding.
  • Min. To Overcoat: 6 hours for Altex Polyurethane Undercoat
  • Max. To Overcoat: 14 days with thorough sanding for Altex Polyurethane Undercoat Max. To Topcoat (see cure notes below).
  • Undercover with Elite® Polyurethane Finish: 12 Days max - freshly sanded within 3 days of topcoating.
  • Outside with Elite® Polyurethane Finish: 10 Days max - freshly sanded within 3 days of topcoating.

CURE TIME NOTES: Maximum cure times before topcoating are based on thorough fine sanding & dedusting within 3 days and solvent wiping of the surface immediately before application of any subsequent coats. (Dry to sand times will increase with higher film builds, and/or lower temperatures. Cure may be advanced by lightly sanding the partially cured surface with 120 grit to open the film up & allow solvents to escape.)

For more information, Product Data Sheets and MSDS. Please see

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