Great Gatehouse, Hampton Court

Special Mortars

RJ2.07

Conservation Mortars: Non-hydraulic stone repair mortars produced from mature Chalk lime putty mixed with stonedusts and sand, colour and texture matched to the stone to be repaired. The repaired stone is often then treated with sheltercoat itself colour-matched to the stone.  Deep repairs are normally filled with a coarse repair mortar prior to the application of the surface repair mortar.

Ash Mortars: Ash mortars are a blend of mature Chalk Lime Putty and sieved coal ash designed to match Victorian ash pointing mortars.  Early historic mortars normally have ash inclusions as kiln-fuel residue, and coal ash or charcoal particles are often added to repair mortars to match this.

Brick Repair Mortars: Brick repair mortars are a blend of mature lime putty and sand but normally require the addition of pigments for an accurate colour match.    

Environmental Considerations: 

Lime Putty mortar is an environmentally sustainable product.

Colours: 

Mortar colour is determined by the sand, stonedust or aggregate mixed with the putty.

Shelf Life: 

Unlimited. Matures with age. Lime putty mortars stiffen during storage, but can be plasticised without the addition of water by thorough re-mixing.

Availability: 

25kg Heat-sealed bags and 15 litre tubs. Mixed to order.

Technical Specification: 

TGN 4  Use of Lime Putty Bedding + Pointing Mortars

Observations: 

The use of stone and brick repair mortars is a skilled operation normally undertaken by an experienced conservator. Non-hydraulic lime mortars do not perform as modern hydraulic lime and cement, and set only by reaction with atmospheric carbon dioxide in the presence of moisture. This ‘carbonation’ is a slow process and control of the drying and curing process by ‘tending’ and protecting is crucial to success and long-term performance. Protections are essential. Do not use below a temperature of 5°C or above 25°C. Do not use if there is risk of frost.