Product Details

No. 3 Epoxy Primer Undercoat


No.3 Epoxy Primer Undercoat is designed for use as:

  • Final surfacing coat for marine topsides prior to applying a polyurethane topcoat
  • High build sanding surfacer to remove orange peel, brush marking and scratches
  • No.3 Epoxy Primer Undercoat may be applied to:-
  • Suitably prepared and primed aluminium and GRP hulls of trailer boats (above and below water) if top-coated with a polyurethane topcoat
  • Direct to sanded  GRP, epoxy laminated wood and epoxy sealed wood, above and below water
  • Direct to coving or filled areas shaped with Filling and Fairing

Download: No. 3 Epoxy Primer Undercoat

Data Sheet: No. 3 Surface Preparation Guidlines Chart



  • Improved Formula
  • Enhanced sanding and de-dusting properties
  • Improved neutral grey tone for top-coat colour compatibility
  • Enhanced gloss hold out for finish coatings
  • Rapid cure to sanding time - even at temperatures below 10°C

Free sanding properties with easy de-dusting - does not clog production sand papers.

Note: DO NOT sand with stearate coated sand papers as this could impair intercoat adhesion

  • Good long term self-recoatability with sanding
  • Lead and chromate free
  • Isocyanate free
  • Excellent build properties when spray applied
  • Suitable for all areas of hull on trailer and moored vessels


Specific Data:

Generic Type: Proprietary Amine Adduct Epoxy

Colour: Grey (and Dark Grey on special order)

Packaging: 1.25, 5 and 10 litre , Two component kits

Mix Ratio: 4 to 1 by volume

Gloss: Flat

Flash Point: 27°C

Thinner:  Spray - Altex Thinner #12

                Brush - Altex Thinner #22

Pot Life: 6 hours at 20°C

Induction Time: 20 minutes

Storage: Store under cool, dry conditions

Density: 1.51 kg per mixed litre

Volume Solids (Mixed): 48%

Theoretical Coverage Rate: 6.4 sq metres per litre at 75 microns dry

Recommended Film Thickness Per Coat: 104 -206 microns wet to obtain 50 -100 microns dry

Application: Spray, brush or roller

Dry Times (50 µm DFT / 25°C / 50% RH): Touch Dry : 2 Hrs,Dry to Sand: 6 Hrs

Maximum Recoat Times (50 µm DFT / 25°C / 50% RH):

With Itself - 5 days (overnight advised)

With Polyurethane - 48 Hrs

Note : If recoating outside of recommended schedule matt surface using fine grade sand paper and re-apply a thin (50 µm DFT) coat of No.3 before proceeding as per the schedule. DO NOT sand using stearate coated paper.

Refer also No.3 Surface Preparation & Re-Coat Guidelines Chart