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Topcoat Primer (EWI-333) – 7kg

Brands:EWI Pro

£30.64 Excl. VAT£34.04 Excl. VAT


  • Waterproof
  • Frost-proof
  • Vapour permeable
  • Increases adhesion between basecoat and render
  • Limits absorption of basecoats
  • Solvent-free
  • Available in 7kg & 20kg

999 in stock


EWI-333 Topcoat Primer 

EWI Pro Topcoat Primer is designed to be used in conjunction with any of our silicone renders. There are several reasons for using the Top Coat Primer (EWI-333); firstly it aids adhesion between the render and the basecoat. Secondly it limits the absorption of the basecoat layer, ensuring the render cures properly – this is especially important during the summer months, giving the installer time to get a finish on the render. Finally the Top Coat Primer can be tinted in the same colour as the render being used, ensuring that there is no basecoat bleed through. 

EWI Pro Top Coat Primer is:

  • Waterproof
  • Frost-proof
  • Vapour permeable
  • Solvent-free

The EWI Pro Top Coat Primer is based on potassium water glass and water dispersion of silicon resin and helps strengthen the substrate and limits its absorptive capacity without compromising its breathability. Our Top Coat Primer should always be used during the summer months because it gives the render applicator more time to get the required finish on the render, however even during the cooler months of the year the primer aids adhesion between basecoat and the silicone render so we do recommend using it all year around. 

The EWI Pro Topcoat Primer is applied on top of the basecoat reinforcement layer (typically EWI Pro’s Premium Basecoat (EWI-225) or EPS Basecoat (EWI-220) and should be allowed to dry prior to applying one of the EWI Pro range of Silicone renders (e.g. Nano Drex Silicone Render, Premium Bio Silicone Render, Silicone Render or Silicone Silicate Render) .


Substrate preparation: All substrates must have appropriate load-bearing capacity. They must be compact, stable, even and free of: dust, grease, anti-adhesive agents, remaining paint, mould, algae, moss etc., scratches and salt efflorescence. Substrates must be uniformly dry. All contamination resulting from grease, oil, anti-adhesive agents should be cleaned by washing with water and detergent and all organic growth should be removed with a wire brush.

Scratched and cracked surfaces should be repaired with levelling mortar. Ensure that any mortar applied is dried and well-bonded.

Product preparation: mix the Top Coat Primer thoroughly before use. The product must not be thinned with water or any other materials.

Application: Apply the EWI Pro Top Coat Primer uniformly to the substrate by using a roller to paint it on. Allow to dry before application of Silicone Render. Works must not be carried out at temperatures below 5℃. Works must not be carried out during rain or snow, or in strong winds or direct sunlight without special shields to limit exposure to weather conditions. Recently rendered walls must be protected against such elements.

Topcoat Primer (EWI-333) Application Conditions

  • Application temperature (air, substrate, materials): from +5°C to +25°C
  • Coat drying time: approx. 4 hours
  • Time to leave before rendering: approx. 24 hours after priming
  • Colour: white (although can be tinted to match the render colour)
  • Coverage rate is approx. 0.2-0.3 kg/m2 depending on substrate structure and absorbency

Storage Conditions

Shelf life: up to 12 months from the date of manufacture. Keep dry and in the original containers at a temperature ranging between 5℃ – 25℃.


Weight 7 kg


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