Making NHL Mortar – Guide

NHL Mortar preparation: can be mixed in normal Mortar mixers.

Put approx two-thirds the amount of water, one third the amount of sand and all the lime followed by the remaining amount of sand and additional water until the required consistency is achieved. Mortar should be mixed for at least 10 minutes. Greater workability and better mortar performance is achieved with less water and longer mixing.(Mortars can be left to stand and fatten up for up to 1-3 hours depending on the mix: and tempered before use.)

Sand:  For building, pointing, base coats and coarse finishes on renders / plasters always use a well graded sharp sand free of silt and clay #10-20 mesh down to #No 200. For finer work: use a fine well graded sharp sand free of silt and clay #100-150 mesh down to #200. (In some circumstances where very fine sands are being used, less binder will be required).

St Astier Natural Hydraulic Limes can be used for a wide variety of purposes.

Typical mix composition.

Volume RatiosCubic feet of Mortar producedSome typical applications
1 bag NHL5 : 1.5 bags of sand2.9Pricking up coat.
1 bag NHL 5 : 2 bags of sand3.0Coping,
1 bag NHL 5 : 2.5 bags of sand3.8Building / render / float / pointing
1 bag NHL 5 : 3 bags of sand4.5Building / render / float / pointing


ProtectionProtect from adverse conditions for at least 72 hours, longer if
conditions persist
CuringFine mist spray as required
CautionDo not use in temperatures below 40 F or above 80F
Reworking/TemperingCan be tempered for up to 8 hours
Injection1 bag NHL 5  10.5 Gallons of clean water. Mix with whisk.
If casein is used water content can be reduced
Gravity Feed1 Bag NHL 5 :  + 16.9 Gallons (2.4 ft Cubic ft approx
) fine sand. Add water to required consistency


Main Rules : Do not over saturate with water, mix well, use well graded sands.

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