Lime Mortar

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For rubble limestone buildings the very best lime mortar is non-hydraulic lime. Construction or tuck pointing this is the best.

This type of lime mortar allows moisture to move through and can be self-healing, and it is softer than the stone

This being said it comes with many conditions we must endure. Very difficult to mix and it takes a long time while being managed to set.

The Hydraulic limes can be used but we compromise several properties. Breathability, hardness and no self-healing. If used, try to stay with the softer 2.0 or the 3.5 and NEVER use any amount of Portland cement!

Very hard to mix, sets extremely slow – in some cases months and while this dries, we must keep it moist – mist spraying daily and must be protected from freezing. This lime was being made for use in two ways

 1)Quick lime to create hot lime mortar

 And when we say hot, this when exposed to water there is a thermic reaction causing very high     heat – is dangerous!

 2) Lime putty to create cold lime mortar. 

Where this has no heat danger it is mighty difficult to mix – you have to rake, chop and hoe. 

Sets very quickly, easy to mix and is harder than the non – hydraulic limes.

Three types of hydraulic mortar’s. 

• NHL 2.0 – Described as feebly hydraulic Sets in 40 hours - soft
• NHL 3.5 – Described as moderately hydraulic Sets in 30 hours - med
• NHL 5.0 – Described as eminently hydraulic  Sets in 15 hours - hard

For much more great information see;

Stone Buildings 

Patrick McAfee