Blowerproof Liquid 'Brush' - A Paint On Airtight Sealing Membrane (5kg)

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Quick Overview

Blowerproof Liquid 'Brush' is a VOC free, water based, flexible, fibre reinforced, polymer providing a unique and sustainable solution for the production of airtight building connections in both new build and retrofit.

Ecomerchant Blowerproof Liquid Brush

The water based polymer is brush applied to create an uninterrupted air and vapour -tight seal around penetrations, and for floor / wall connections, wall / ceiling joints, and roof connections

Blowerproof liquid creates a seamless, continuous air and vapour -tight seal over cracks and gaps. Because the seal perfectly follows the contours of the substrate and in combination with the high flexibility and superior adhesion, the connections remain airtight over the long term. Blowerproof liquid is the fast, flexible and durable solution for all airtight connections.


Ideal for sealing

  • Service penetrations, pipes, cable, ducting etc

  • Floor to wall junctions

  • Ceiling to wall junctions

  • Window / door jambs

  • Steel decks


Blowerproof Liquid  Brush comes in a re-sealable 5kg tub. Allow up to 1kg per square metre on highly porous surfaces for non porous surfaces allow 750grams per square metre. Also available as Blowerproof Liquid Spray - please call for the spray version.

One 5kg tub will cover approximately 83 linear metres at 75mm wide.

Price is per tub

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Blowerproof Liquid 'Brush 9

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 Blowerproof Liquid Brush is a fibre reinforced paste designed for application with a brush,

NB. There is also a spray version for larger / commercial projects you can see more about Blowerproof Liquid Spray by clicking on the 'More Info' tab above. If you have a larger project the spray version may be your best option, please call us for pricing on our applicator service

Ecomerchant Blowerproof liquid brush


















Liquid Proof Blower Brush Benefits

  • Versatile for use on a wide variety of building materials like concrete, stone, wood, metal, aluminium,  insulation , EPDM, etc. *
  • Suitable for new buildings and renovation
  • Seamless and secure even with difficult connections
  • Quick and easy application
  • Moist surfaces are no problem
  • Can be over plastered, rendered or painted
  • Fully water-borne
  • Blowerproof Liquid Brush is an optimal product for materials of different coefficients of expansion
  • Extensively tested for adhesion and elasticity

Material: waterborne polymer paste reinforced with fibres

Colour: Blue colour changes to black as drying is completed

Consumption:  between 0.75 and 1.0 kg / m² (about 1.0 mm in thickness) dependednt on substrate porosity

Substrates: bricks, blocks, concrete, stone, wood, metal, aluminium,  insulation , EPDM, etc. *

Extensibility: 380 % (at 0.6 mm dry film thickness )

Crack bridging > 2 mm ( 0.6 mm dry film thickness )

Diffusion resistance number: 76 854 μ

Storage time : 1 year ( in unopened packaging )

Storage temperature : between 5⁰C and 20⁰C

* Adhesion Reports available on request

Ecomerchant Blowerproof liquid Brush

General application guidance

  • Remove dust and loose particles; remove surface contaminants which may affect adhesion. Treat blemishes; fill holes and cracks ≥3 mm
  • Do not apply when (surface) temperature < 5 ° C
  • Blowerproof Liquid Brush is ready for use, do not dilute with water or solvents; briefly mixing with hand mixer
  • Use a square brush
  • Apply thick enough to ensure air-tightness; indicative consumption: 1.0 kg / m²
  • Avoid during the drying phase contact with any kind of water, other liquids or construction chemicals
  • Cleaning Material: immediately after use with water
  • At least 24 hours to 48 hours to dry before applying another material on the dried - black - finish. (During drying, the colour changes from blue to black).



Typical Applications

Pipes & Penetrations

Ecomerchant Blowerproof Liquid BrushNumerous energy test reports, performed at the end of a construction project, show that pipe penetrations are in many cases a cause for not obtaining the requested level of airtightness. 

For the airtight sealing of of pipe penetrations: first plug gaps wider than 5mm with Blowerptoof Gap Filling Mortar or polyurethane foam around the pipe penetrations; then apply 2 layers of Blowerproof Liquid Brush with a flat paintbrush; in all cases, apply a sufficient, well covering layer to guarantee airtightness.



Window jambs

Ecomerchant Blowerproof Liquid BrushApply a protective tape at max. 5 mm from the side of the profile. This tape needs to be removed shortly after finishing the application of Blowerproof Liquid Brush.  





Floor to Wall

Ecomerchant Blowerproof Liquid BrushIn order to obtain a sufficient airtightness of a building, it is important to make the floor/wall connections on the inside of a building airtight. 

Blowerproof Liquid is an airtight coating which is sprayed with an airless spray device on these floor/wall connections. The substrate must be dust free, solid and free from large cracks or gaps before starting the application. Holes and joints need to be plugged beforehand: large holes and joints (> 5mm) can be repaired with a fast setting cement based product or polyurethane foam, small holes and joints (2-5mm) can be sealed with Blowerproof Liquid Brush.

For larger projects Blowerproof Liquid can be sprayed with an airless paint spray device; this fast application method allows applying up to 300 linear meters per day. See more  by clicking on the 'More Info' tab above

For smaller projects, such as private houses, Blowerproof Liquid Brush can be used with a flat paintbrush, suitable for water based products. Apply in two coats; second coat must only be applied when the first coat is completely black.

Wall to Ceiling

Ecomerchant Blowerproof Liquid BrushThe wall/ceiling connections also need to be made airtight, this can be problematic when the surfaces are of two different types of material such as red brick/concrete or steel/concrete. Different construction materials react differently to changes in humidity and temperature, which can lead to small cracks in plaster or another type of finishing, and so creating air leaks. 

For wall/ceiling connections, both spray and brush applied products can be used: 

Blowerproof Liquid sprayed with an airless paint spray device (1 layer) or Blowerproof Liquid Brush which is applied with a paintbrush in two layers. Apply in two coats; second coat must only be applied when the first coat is completely black.

Examples of an airtightness measurements after application of Blowerproof Liquid Brush are available as a downloads by clicking on the ‘Technical Info’ tab above

Reports - see downloads by clicking on the 'Technical Info' tab above

  • WTCB test reports available, incl. ageing:
  • Damp diffusion resistance factor 
  • Adhesion tests on Aerated concrete blocks, red brick and concrete brick; dry and humid substrates
  • Adhesion tests on OSB and MULTIPLEX; PVC, aluminium, metal, EPDM
  • Adhesion tests of plaster on Blowerproof Liquid coating
  • Elongation at fracture: 250 @ 350%
  • Elongation/tensile strength 120% elongation;  42 N/50mm tensile strength



Test Category

Blowerproof Liquid comes in two forms, the brush applied fibre reinforced paste as described in the previous pages (the one we have available to buy online or direct) and in a more liquid form for direct airless spraying.

We only sell the brush version online, the spray version is typically applied by a professional applicator. We are currently seeking projects for us to apply the spray version with our own trained applicators. if you have  a project where the spray applied version could help we are keen to hear from you, please get in touch.

Blowerproof is a new product to the UK; throughout Europe the application of a spray airtightness membrane is a common way of achieving the high standards of airtightness enshrined in their building regulations so this product has a huge number of references and case studies including detailed post occupancy monitoring.

This means that there are plenty of experienced spray applicators. We have an arrangement with the Belgian, manufacturer that their application teams will be available to apply in the UK, if you have a project where a larger area of Blowerproof Liquid could be applied please call us and talk to us about your project.

We are keen to use a number of case studies to both provide UK based applicators live training by the experienced Belgian teams but also to demonstrate the enormous cost savings and the robust performance of the products.

All spray applied projects will be tested for airtightness post application and the manufacturer will provide a guarantee of performance for each individual spray applied job.

If you have an application that might benefit from the speed and efficiency of Blowerproof liquid spray please get in touch by calling 01793 847 444

A couple of questions? 

Q. What is the difference between the brush version and the liquid one?

A.  The liquid version has no fibres it can be applied in a single coat on less porous and smoother substrates and two coats for more porous and rougher surfaces unlike the brush version two coats can be applied quickly around 10 minutes between coats. With the fibre reinforced version applying a second coat before the first is dry could lead to damage caused by the brush creating gaps or breaks in the original seal. 


Q. Can I spray apply myself or do I need a professional?

A. We would prefer you use a professional applicator, however the actual spraying technique is quick to learn and the equipment relatively easy to hire, if you understand the principles of airtightness and can handle a sprayer then you will probably do a good job.


Q. Is it only available in blue/black?

A. No there is a white version specifically used where the topcoat will be plaster, otherwise the default is blue/black


Q. How much can be applied in a day?

A. Using the sprayer around 300 linear metres a day


Q. What can you put over the applied product?

A. Pretty much anything from paint to plaster, render or dry lining


This video shows how Blowerproof is applied. We are currently looking for early adopters in the UK to provide case studies, if you have a building project of any size where Blowerproof could help significantly improve the airtightness and energy efficiency of the building please call and let us know.

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