Premixed Fat Lime Mortar - Shale - For Building and Pointing

gives a consistent, accurate mix hence removes the potential for mixing and gauging errors on-site.

minimises waste - enables you to 'knock-up' as much as you require in a day, anything left over can be reused, so nothing goes to waste.

helps to keep the site organised and clean.

colour and texture variations can be accomodated making sure regional variations are maintained.

high quality aggregate selection produces a very workable 'fatty' mix, minimising shrinkage.

this product is made in our manufacturing yard that operates under our iso9001:2008 quality management system and the Green Dragon Level 2 environment standard.

You should be aware that aggregates occasionally run out, eg, if a quarry closes. If it is important that you maintain the colour for the whole job, then you should ensure that you purchase sufficient supplies where possible.

How much mortar do I need?

Please use our quantity calculator to assist you to calculate the quantity of this product that you may require for your particular application. You will need to register to access this or call our sales team for advice on 01874 611350.

What basically is the difference between the different types of lime?

A non-hydraulic lime or lime putty is made by slaking burnt lime in excess of water. It can then be mixed with aggregate to produce mortar. This type of lime is used in our premixed lime mortars which are supplied 'wet' and ready-to-use, they just need 'knocking-up' on site. These limes are slower to set and produce a softer mortar but their strength is good flexibility and excellent vapour-permeability.

Natural hydraulic limes are made from chalk or limestone containing clay impurities. They tend to have a faster and harder set than high calcium lime but they are less flexible and less vapour permable/breathable than non-hydraulic lime. They are available as a powder to be mixed on site with aggregates and water.

What type of lime mortar should I use?

The type of mortar you use should always be softer than your building components i.e. stone or brick, this is really important for the longevity of the building (choosing the right strength will mean that the fabric will last longer!)

GENERALLY - internal or sheltered external (at the right time of year!) pointing and building work can be done using a premixed lime mortar, if you are working on an external application that is exposed or working late in the year and through to the Spring, then a hydraulic lime is recommended. Please see Choosing a Lime Mortar in Documentation.

Should I add a little cement to my lime mortar to give it strength?

It is often thought that by adding a little cement to lime mortars, typically in the ratio 1:2:9 (cement : lime : sand), that a lime mix can be strengthened. While this may induce a quicker initial set, this may prevent proper carbonation of the lime and produce a weaker mix in the long-term and so it is not advisable!

If you wish to increase the speed of set, perhaps consider using a pozzolan in your mix (see separate entry) or using a stronger hydraulic lime.

What is a pozzolan?

These are materials that can be added to a lime mortar to increase its set. They normally contain a form of clay particles containing silica and alumina which will combine with free lime. They are often natural materials such as fly ash, brick dust or calcined clay. They are often seen in old mortars. If you need to match an old mortar, then we are able to help, see our Mortar Matching Service.

Which hydraulic lime should I use?

We supply the only British hydraulic lime (Singleton Birch) which we prefer from a sustainability point of view, it is an off-white and gives a softer mortar/plaster.

We also supply the Castle Hydraulic Lime which is a purer white and gives a faster set and a stronger mortar/plaster.

Care must be taken to choose the right hydraulic lime (even within the same designation) according to its technical charateristics and the particular building application, there is concern that because the stronger hydraulic limes set quickly they are being used for applications where they are not appropriate in the same way that cement is not appropriate. See the technical sheets and application guides for the different products in Documentation.

If you are not familiar with the different hydraulic limes, it would be worth doing/getting your contractor to do sample panels as they behave and look differently or call 01874 611350 for more advice.

Can I use ordinary building sand to make a lime mortar?

Lime mortars generally perform best with minimal shrinkage if made with a good quality, well graded, sharp sand.

Building sand tends to be too fine. Pit sands and not sea sands should be used as the salt residue in sea sands can cause reactions in lime mortars and we do not want to introduce salts into the building. For an environmentally-friendly alternative, see our glaster products made with recycled glass instead of sand.

Can I use an ordinary drum mixer to mix lime mortars?

Yes but for larger quantities we would recommend using a forced-action, pan mixer or a mortar mill.

Where can I get hold of these mixers or mills?

We hire out and sell small 100 litre mixers and hire out mortar mills. We currently have a towable, diesel mill as well as a static for larger quantities.

Why do I need to protect lime work?

Lime products need to carbonate (not just set) which they need to do by absorbing Carbon Dioxide in the presence of moisture. It is therefore important to create the correct conditions for carbonation which comes through experience but is vital to the success - refer to the application guides for each product for details on protection - it is one of the most important points to ensure a successful result!

Different limes, different applications, different backgrounds (even in the same building), different times of the year and different elevations on the same site will all require careful attention and possibly different measures.

Most of the failures that we see are down to a lack of appropriate tending to aid carbonation as even a poorly specified/selected lime type can actually succeed if applied and cared for appropriately after all we did not historically have the range that we have now! As a result, we concentrate on this particular aspect on our training courses and in our application guides and are happy to discuss any aspect of it with our customers - call 01874 611350! We want your job to succeed and most do!

Should I stop using lime in the winter?

It is not recommended to use lime products (lime mortars, renders and limewashes) when temperatures are liable to fall below 5°C (41°F) for several weeks/months after the product has been used, this is especially true for non hydraulic and the weaker hydraulic limes. In practice this means that unless adequate weather protection is provided they should not be used externally until next spring - please see application guides and our using lime in winter information sheet in Documentation.