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Ashlar Joints – Guide

Traditional ashlar jointing and bedding mortars were made with lime and crushed chalk, usually with a small amount of crushed stone or sand added for bulk. This was mixed on a marble slab with just enough linseed oil to grease the tools, it was made up into a consistency similar to stiff glazing putty, wrapped in oiled cloths and stored until required.

Material. Supplied in dry powder form in 5 gallon plastic buckets with re-usable airtight lids.
Ready for site mixing with clean drinking water and linseed oil (optional).

Background. Generally, natural stone (Ashlar blocks) or rubbing bricks, for building, or existing masonry for re-pointing. The background should be clean and free from loose or friable material, well washed to remove dust. Dampen high suction units. (Do not dampen very low suction materials such as granite)

Application.
Laying sawn six sided blocks or rubbing bricks.
Butter on to beds and perpendicular ends a full bed of mortar, firmly pressed into place to slightly more than the desired bed thickness and lay next block firmly in place to line and level by tapping firmly and repeatedly. Excess mortar will squeeze out. Leave excess in place for several hours.

Laying single faced masonry units.
Lay a ribbon of ashlar mortar (approximately 1″ in width) on the leading edge of the ashlar faced unit and a bed or normal coarse stuff to bed the irregular meeting faces. Tap down the stone to line and level, excess ashlar mortar will squeeze out. Leave excess in place for several hours.

Mixing.
The materials are firstly mixed dry to fully combine all the ingredients and just sufficient water is added to make the material into a dough like consistency, a good double handful size lump of the mortar has a thimble full of boiled linseed oil added and kneaded into the mix until it leaves the hands clean and is fully plastic. (Disposable
or rubber gloves are usually worn for this process). The mortar should be used within 24 hours, if being stored for more than an hour it should be wrapped in polythene to keep it moist. Because it is feebly hydraulic the mortar sets slowly but positively and on final set and full carbonation resembles hard chalk, matching exactly traditional ashlar jointing.

Consumption:
3281 linear feet of bed joints, at 3/32″ thick, and 4″ on bed requires 52 Gallons of mortar. Re-pointing 3281 linear
metres of 3/32″ thick joints at a depth of 3/8″: 5 Gallons of mortar are required.

Re-pointing:
See Pointing with NHL (re-pointing ashlar joints)

The above details are given for information purposes only. Final dosages and application should be checked with our technicians.
The Factory reserves the right to alter specifications

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