Edinburgh:
Masons Mortar Ltd
77 Salamander Street
Edinburgh EH6 7JZ

Tel: 0131 555 0503
Fax: 0131 553 7158

Glasgow:
Masons Mortar Ltd
Unit I, Woodville Court
Woodville Street
Glasgow G51 2RL

Tel: 0141 445 4812
Fax: 0141 445 8898

Fife:
Masons Mortar Ltd
Block 2
Woodend Industrial Estate
Cowdenbeath, Fife
KY4 8HW

Tel: 01383 514 460

Newcastle:
Masons Mortar Ltd
Unit 11
Brough Park Trading Estate
Fossway, Newcastle upon Tyne
NE6 2YF

Tel: 0191 908 9234

Ashlar: Bedding and Pointing mortar
Ashlar: Bedding and Pointing mortar.

Traditional ashlar jointing and bedding mortars were made with fine sieved lime, either non-hydraulic or feebly hydraulic lime and crushed chalk, with or without a small amount of crushed stone or sand added for bulk where joints required. 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. Where non-hydraulic lime was used, this could be stored in a damp or oiled cloth to prevent drying, where feebly hydraulic or moderately hydraulic lime was used, it would be mixed and used on the day or within 24 hours depending on the type of hydraulic lime used.

Material

Non-hydraulic: Supplied as a fine sieved pre-mixed putty mortar in 20 or 10 Litre plastic buckets with re-usable airtight lids.
Ready for use with additional on site mixing to increase workability (without the addition of water)
Feebly hydraulic NHL 2 or Moderately Hydraulic NHL 3.5: Supplied as a premixed dry powder mortar for mixing on site with the minimum amount of clean potable water to produce a stiff putty to which a small amount of linseed oil may be added if required.
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.(Joints not exceeding 3mm )
Butter beds and perpendicular ends a full bed of mortar, firmly pressed into place to slightly more than the desired bed thickness, lay next block in place to line and level by tapping firmly and repeatedly such that a slight excess of mortar is squeezed out when the correct joint size is achieved.(this indicates full face contact with the units) Leave excess in place for several hours.
Laying single faced masonry units.(Traditionally hewn ashlar masonry dressed only on the face)
Lay a ribbon of ashlar mortar (approximately 25mm 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 and correct joint size, excess ashlar mortar will squeeze out. Leave excess in place for several hours or longer before trimming back.

Re-Pointing Existing Masonry

Joints should be properly raked out using appropriate tools, avoiding damage to the arises of masonry units. Joint depth should be consistent and the back of the joint squared, with masonry faces being free of loose or friable materials and dust free.
Protection of the masonry with tape avoids staining. Joints must be thoroughly washed clean before applying new mortar and remain damp enough to control suction during application and initial curing.
Cleaning excess mortar from the face of masonry may cause the lime binder to spread over the surrounding units and may lead to unsightly staining.
Tape on either side of the masonry, carefully placed to accurately follow the open line of the joint will provide protection against staining. In addition, it will allow very narrow joints to be filled with a small flat spatula such as the square end of a trowel and square and allow the mortar to be firmly pressed into the joint. Excess mortar can be left over the taped edges until the mortar stiffens sufficiently for it to be struck to flush when the tape is removed, usually within 24 hours.
Where the edges of the masonry are worn or damaged from previous repair, carefully cutting of the stiffened mortar to the weathered edge will create a fine shadow gap and minimise the visual impact of a white mortar filling irregular features in the masonry.
Joints over 3-5mm are not true ashlar joints and a mix with a higher sand content should be used. (see fine jointing mortars guidance sheet)
Deep or open joints particularly at cornices and projections may be impossible to fully and adequately fill, leading to tip pointing, in these instances, consideration to the Clay Cup method should be given. (see Clay Cup method guidance sheet No x x)

Mixing Hydraulic Ashlar Mortars

The materials are supplied dry, ensure all components are fully combined. Add just sufficient water to make the material into a dough like consistency, If required a good double handful size lump of the mortar add a tablespoon of boiled linseed oil and knead into the mix until it leaves the hands clean and is fully plastic. (Disposable or rubber gloves are usually worn for this process). Feebly hydraulic mortars NHL 2 should be used within 24 hours. Moderately hydraulic mortars NHL 3.5 should be used within 4-6 hours. Keep all mixed hydraulic mortars covered in sealed containers once mixed.
Moderately hydraulic lime mortars will require re-working.


Mixing Non-Hydraulic Ashlar Mortars

Supplied as a ready mixed wet plastic mortar complete with Linseed oil, the mortar may be stored indefinitely in airtight sealed close covered frost free conditions. The mortar may stiffen (loose initial workability) in storage or transit, but will with re-working without additional water return to a fully plastic putty, a gloved hand will provide the quickest method of re-working. Only ever add water to a non-hydraulic ashlar mix where there is a need to soften the putty consistency for specific applications, such as very tight joints (less than 1-2mm)
Consumption:
1000 linear metres of bed joints, at 2mm thick, and 100 mm on bed requires 200 litres of mixed mortar. Re-pointing 1000 linear metres of 2mm thick joints at a depth of 10mm: 20 litres of mixed mortar are required.

Health and Safety

Dry bagged materials contain fine powders and fillers: Use suitable PPE.
Always wear properly fitting dust masks appropriate for the hazard classification; See separate COSHH sheet for lime and fine silica sand or titrated chalk fillers.
Avoid ingestion, contact with skin and eyes.
Lime is an alkaline material in wet and dry conditions and poses a risk in contact with, the eyes and exposed skin.