Polypropylene & Belmix Flock Fibres

Mortar addition, acting as an alternative to animal hair.

Key Benefits

  • Budget-friendly and effective alternative to traditional animal hair
  • Assists with mitigating cracking and plastic shrinkage
  • Can aid in controlling shrinkage on high-suction backgrounds
  • Available in two types



5% discount on orders over £500 (Excluding Vat & Delivery). For larger projects visit our pricing page.

Product Variations

Product OptionPrice (Ex VAT)
12mm Fibres / 0.9kg: £10.84 £13.01 inc VAT
19mm Fibres / 0.9kg: £10.30 £12.36 inc VAT
50mm Fibres / 0.9kg: £10.23 £12.28 inc VAT
18mm Belmix Flock Fibres / 0.9kg: £8.14 £9.77 inc VAT
18mm Belmix Flock Fibres / 25kg: £170.50 £204.60 inc VAT
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Polypropylene Fibres can be used as a mortar addition to replace the historic use of animal hair in a lime mortar. Polypropylene Fibres have similar properties to animal hair, they help to mitigate against cracking from freeze/thaw cycles and shrinkage and improve the impact and fire resistance. They can also help to increase the load spread of a render and are particularly useful when a mortar is used for specific purposes like bedding slate and rendering onto lath.

Fibres like other types of synthetic offerings they have proven to be an extremely effective and honest alternative to hair. They are not as traditional as animal hair, however they are cost effective and easy to use and they do not degrade in the same way, meaning they can be added to premixed mortars.

We supply two types of fibres:

– Polypropylene Fibres – Simple straight fibres, available in three lengths, 12mm, 19mm and 50mm.

– Belmix Flock Fibres – Available in 18mm length.   As a “Flock” it differs to many other synthetic types as the base fibre has undergone a “Flocking” process where additional smaller fibre particles are bonded onto its surface creating a greater surface contact area for the mortar matrix. We have been supplying this product for over 8 years and are more than happy with its performance.


Used In Conjunction With


Are of use is for Lime & Cement Renders.

Fibres are a lot easier to introduce than animal hair and can simply be sprinkled into the mortar requiring only a few minutes mixing to be distributed.

Addition rates will vary according to application, and (FOR GUIDANCE PURPOSES ONLY) can vary from 500g per tonne when used as an aid to control shrinkage cracking on high suction backgrounds, to as much as 2Kg per tonne (of mixed mortar) for rendering onto lath.

Once added into the render they should require only a few minutes mixing but most importantly, they must be distributed as evenly as possible throughout the mix to be effective.

Often used with Natural Hydraulic Lime, including Saint-Astier Natural Hydraulic Lime and Otterbein.

Each project is unique, always seek professional advice before undertaking a project.

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