A multipurpose medium-textured mortar, render and plaster with a high free lime content to replicate the properties and performance of historical mortars, providing a convenient alternative to traditional hot mix and avoiding the challenges of mixing quicklime on site.
£15.77 £18.92 inc VAT
Estimated lead time is 3-5 business days
Minimum order quantity of 20 bags
Cornerstone Heritage MK Medium is a dry ready mixed multipurpose lime mortar, render and plaster for general building, pointing and coarse render coats with a minimum of a two-coat render application. Available in the colour buff.
As part of the Cornerstone Heritage range, multipurpose mortar, render, and plaster have been refined to closely replicate the properties, mix ratios or performance of traditional mortars and renders historically used in the UK.
Manufactured by Cornerstone utilising Lhoist CL90 and the pozzolan Metakaolin to create a highly breathable and high free lime content lime mortar to closely replicate the historic mix ratios of traditional mortars found in the UK.
In addition, Cornerstone Heritage MK Medium can optionally be blended with additonal conservation appropriate additives to enhance the mortar’s physical and mechanical characteristics while retaining all the benefits of a highly breathable pure lime mortar. Available as standard with Lhoist CL90, with the addition of Metakaolin gauged 10%. Also available with Metakaolin gauged at 5% upon request. Other mix ratios and the inclusion of fibres are available upon request.
Well-suited for applications requiring high vapour permeability and porosity for the conservation or restoration of heritage buildings, aiming to achieve a sympathetic repair or replacement of a historic mortar, render or plaster without the challenges of specifying or onsite mixing a hot mix mortar.
With a diverse range of lime-based products, Cornerstone defies the standard one-size-fits-all approach, providing refined solutions to tackle each project effectively. Their products can be found on prestigious buildings worldwide, blending innovation with tradition to meet evolving industry needs.
As with any natural product, variations in colour, texture and shape may occur. In addition, images may vary slightly from actual products due to these natural variations and screen resolution. For the best consistency, ensure to acquire a sufficient amount of material with your order to avoid batch-to-batch variation.
Suitable for internal or external use, where the binder strength is appropriate for the host background or surface.
Relevant for general building, pointing and including coarse render coats, typically including float coats and topcoats with a minimum of a two-coat render application. For a coarse basecoat, explore Cornerstone Heritage MK Coarse.
For similar mortar with less strength, ultra-high vapour permeability, and less capillary water absorption, explore Cornerstone Heritage Trass Medium, which is ideal for masonry in exposed environments. Appropriate for various project types, including conservation or restoration.
A 25kg bag will produce approximately 14.5 litres of mortar or render. For rendering, this covers roughly 1.5m² at a 10mm thickness. For pointing, this will fill roughly 1.5m² of joint at a 10mm depth. The width and depth of the joint will influence this estimation. On-site trials are advised for the best yield indication for your specific project.
Be aware that the finish applied to the mortar will influence the final appearance. Our team can advise you on finish methodology options that might best suit the final texture of colour you aim to achieve for colour-sensitive projects.
As natural products, our sands may exhibit variations in colour, texture, and shape. While these variations are minimal, when colour consistency is crucial, we strongly advise each elevation is completed using material from the same batch.
Supplied in 25kg polythene-lined and colour and batch-code paper bags for easy identification onsite and palletised for ease of transport, storage, and handling. FIBC tonne bags are also available.
See the Technical Data and Documentation section for detailed product information, application guidance, and datasheets. Always review any available documents before use. Each project is unique, always seek professional advice before undertaking a project.
When working with lime, an alkaline material, always ensure you wear the appropriate PPE. Browse our range of tools and PPE to get started.
Store in indoor covered and dry conditions, protected from environmental conditions, including water, damp or frost and clear from the ground. Always reseal packaging if product is still present.
Do not use in temperatures below 5°C or above 30°C, or if freezing conditions are predicted within the following few weeks, including wind chill. We always advise following best practices for curing and protecting fresh lime renders and plasters. Protect from adverse environmental conditions, including frost, rain, direct sunlight and drying winds.
Brand
Cornerstone
Binder
CL90, Trass
Coat
Basecoat
Colour
Beige-Tan
Material
Natural Sands, Additives, Non-Hydraulic CL90 Hydrated Lime, Rhine Trass
Work
Rendering, Plastering, Building
Use
Internal, External
Application
Manual
Mix Ratio
1:2
Aggregate
5mm down sharp flint sand
Coverage
A 25kg bag covers approx. 1.5m2 at a 10mm depth for pointing or 10mm thickness for rendering
Yield
A 25kg bag yields approx. 14.5 litres
Always read any available datasheets and documentation before use.
Stock Quantities and Lead Times
Stock quantities and lead times are estimated and may differ or increase based on the order size and shipping method. If your timeline is sensitive, get in touch with the team.
Palletforce
Pallet orders with Palletforce Economy are typically dispatched from Cornish Lime within 1-2 business days, providing your item is in stock and not made-to-order. Once dispatched, Palletforce will deliver your order within 3-5 business days, depending on your location. Please ensure that your site can accommodate articulated lorries or similar-sized vehicles.
Local Delivery
The Cornish Lime team provides local delivery with a 18-tonne vehicle with a crane to assist with unloading. You will be contacted by phone to arrange delivery and ensure your site can accommodate our vehicle.
APC Parcel Courier
Orders shipped by APC parcel courier are typically shipped the next business day and arrive within 2-3 business days, providing your item is in stock and not made-to-order. APC will contact you via email with delivery information, and orders can be tracked on the APC website.
Premium or Expedited Service
For a premium or expedited delivery service, please get in touch to discuss if this option is available for your order.
For further information, see our delivery information page.
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