SMET NHL 3.5 is a high-quality, pure Natural Hydraulic Lime binder, produced under ISO 9001 and ISO 140014 management systems to EN 459-1. The moderate hydraulic strength development of SMET NHL 3.5 makes it suitable for producing lime mortars for masonry work, rendering, plastering base coats, and limecrete.

A moderately hydraulic lime binder for the production of mortars it is particularly suited for ecological new builds, restoration, and preservation work.  The product’s special composition allows the mortar product to breathe and also permits constant hygrometric exchange between the substrate and the environment.


Related Downloads

icon-pdf  TDS SMET NHL 3.5

icon-pdf  SMET and Haldane Fisher NHL Brochure

Benefits of SMET NHL 3.5 Binder

• Historical, gypsum and cement-free NHL
• Produces highly breathable mortars
• Highly sulphate-resistant
• Low-stress hardening process
• Excellent subsequent hardening
• High water retention and elasticity in produced mortars
• Excellent bond properties to masonry
• EN 459-1

Recent conservation job where SMET NHL 3.5 was airlifted into position by Rainey Restoration Ltd

Production Of Mortars For Masonry

Binder: sand ratio: from 1: 1.5 to 1:3 depending on site and material conditions, joint size and sand grading. Always use well graded clean sands ( 3 – 4mm down to 75 microns).

Production Of Mortars For Rendering

1. Scud Coat (3-5mm) Binder: Sand ratio: 1: 1.5
2. Base Coats  (10mm) Binder: Sand ratio: 1: 2
3. Finish Coat (5-10mm) Binder: Sand ratio: 1: 2.5


SMET NHL 3.5 must be mixed with clean, well-graded sands and clean water without additives. Do not mix or apply if the temperature is below +5ºC or over 30ºC. This product must not be mixed with gypsum or be applied to gypsum-based backgrounds. Avoid over-mixing, as this can adversely affect performance and strength.  Material that has set must not be re-mixed. For interior applications, care must be taken when using heating systems. High or rapidly changing temperatures may affect the hydraulic setting reaction of the mortar/render and cause cracking and/or adhesion problems. Delay the implementation of heating systems for as long as possible and heat up interiors gradually. Other unfavourable conditions, such as overly wet backgrounds, low background temperatures, and low air temperatures can delay setting. During and after application, protect the mortar/render from adverse weather conditions, such as direct sunlight, strong winds, rain, and frost.


QR CODE – links to Haldane SMET NHL BROCHURE

Technical Details for SMET NHL 3.5 Binder

Unit Average values Conformity to Standard
Physical Properties Mini Maxi
Fineness at 90 µ % 4.6 15
Fineness at 200 µ % 1.0 2
Expansion Expansion (soundness) mm 0.2 2
Bulk density kg/dm 0.769
Real density g/cm3 2.75
Blaine value cm²/g 8270
Water content % 0.42 2
Mechanical Properties
Beginning of set min 266 60
End of set min 401 1800
Mechanical strength at 28 days MPa 5.71 3.5 10
Chemical Properties
SO3 % 1.38 2
Free lime content % 30.06 25

Packaging: Available in 25 kg bagsPURCHASE DIRECT or VIA HALDANE FISHER 

Also available in designation: SMET NHL 2 and SMET NHL 5

Read more on SMET NHL Binders

SMET NHL articles