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St Astier NHL 3.5

St Astier


Prices Include VAT


Prices Include VAT

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St. Astier is Europe's most technologically advanced producer of natural hydraulic limes and the market leader in the UK. They are highly respected in the Lime industry, having been in continuous production since 1851 and long renowned for quality, performance and unparalleled technical support.

St Astier NHL has three standard strengths: NHL2, NHL3.5, and NHL5.

NHL 3.5, the most popular of St. Astier's high-quality Natural Hydraulic Limes, is suitable for countless applications as a mortar or render in the care and repair of older, traditionally constructed buildings.


Information about Natural Hydraulic Limes (NHL)

These limes are produced from impure limestone, which allows for a hydraulic set. They are supplied in dry powder form and begin to set through a chemical reaction called hydration when water is added. They are available in 25kg bags.

  • Suitable for most masonry types
  • High vapour permeability - Breathable
  • Flexible - Good modulus of elasticity
  • Tolerant to exposure

NHL 3.5 is the most popular trade choice and offers a medium strength. It is suitable for numerous applications as a mortar or render in the care and repair of older, traditionally constructed buildings. It also offers a breathable mortar/render, allowing moisture to be wicked out of masonry, even though it may not always be the most suitable NHL for certain instances where an NHL 2 might be more appropriate.


Use & Application

  • NHL3.5: This is the most popular option and is suitable for mortars, renders, plasters, and grouts. It's best used on reasonably sound to challenging backgrounds in sheltered to moderately exposed locations.

  • You should mix it with clean and well-graded sand at a ratio ranging from 1:1.5 to 1:3, depending on the application and/or background conditions, the joint's size, and the sand's fineness. 

  • The working temperatures should not be below 5 degrees Celsius or above 30 degrees Celsius. Ensure that high-suction materials are thoroughly dampened before application. Using appropriate curing methods, avoid rapid drying due to high temperatures or strong winds. Fresh mortar should be protected from frost, rain, direct sun, and strong winds for at least 48 hours, depending on the time of year.
  • Please refer to the Technical Data and Documentation section for more detailed product information, application guidance, and datasheets. Always make sure to read the available datasheets and guidance before use. Each project is unique, so it's always best to seek professional advice before undertaking a project.
  • When working with lime, an alkaline material, always ensure you wear the appropriate personal protective equipment (PPE).



Protecting St Astier NHL Mortar

St Astier NHL 3.5 Product Data Sheet