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Stone Restoration Services Ltd
Unit 12 Communal Site
Anchor Lane
Abbess Roding
Ongar
Essex
CM5 0JR

Tel: 01279 876994
Fax: 01279 876995
Email: info@srslimited.co.uk

Registered office:
15 Whitehall
London
SW1A 2DD
Registered in England No.3507284

Cleaning Methods

There are many different ways of cleaning buildings, and the method employed will depend upon many factors such as construction materials, the extent of deterioration, and the degree and nature of the soiling - some of the forms used include:

  • Water cleaning
  • Traditional Masons Nebulous Water Cleaning
  • Low pressure air abrasive systems (TORC)
  • Super Heated systems (DOFF)
  • How water pressure
  • Abrasive cleaning
  • Poultice cleaning
  • Paint removers
  • AGS (Anti-Graffiti System)
  • Tensid approved contractor - www.tensid.com
  • Blast cleaning
  • Chemical cleaning
  • Sika Approved Contractor

Stone Restoration Services are fully aware of the unforgivable damage that other inexperienced companies have caused in the past by over-aggressive systems and poor workmanship to both new and historic buildings.

We are fully equipped with some of the most conservation-minded machinery and strive to ensure the most sympathetic approach is selected. We are approved contractors for both TORC, DOFF and Tensid and hold full stock of all products and machinery.

Our operatives have a wealth of experience in all systems and processes -our Masons are time served and trained - some of our members now have two of their generations within our Company. We currently have an ongoing commitment to the new (2006) "Façade Preservation" Apprenticeship scheme whereby our newer cleaning operatives will be trained for a minimum of 2 years under this apprenticeship prior to being permitted to undertake any cleaning works.

Repair

It is imperative that any repairs have true compatibility and will behave in the same manner as the existing structure. Repairs must expand and contract with the masonry and be breathable enough to allow water vapour to escape thus avoiding failure of the masonry due to freeze/thaw cycles or salt re-crystallisation.

Pollution, poor maintenance and inadequate detailing can all damage historic facades. There are no standard solutions to repair problems -each project must be individually assessed. Our craftsmen are qualified to repair stonework, brickwork, terracotta, faience and stucco rendering to the detailed requirements and standards of English Heritage and conservation officers.

Procurement of new materials can be an elaborate process and one which we have the added advantage managing "in house" - all selection, procurement, storage, detailing and production of all stone work is dealt with at our premises and eradicates any production delays or site adaptation. Design and Procurement

Cleaning

Dirt or soiling can take many forms: airborne particles, gaseous pollutants and organic aerosols from industrial or vehicular emissions; biological soiling by algae, fungi, bacteria and lichen; non-biological soiling by iron staining, paint or graffiti - the list goes on. It may be that the soiling causes stone deterioration or decay, or reduces the permeability of the substrate; or it may simply appear as an unsightly surface discoloration.

Architectural surfaces can build up a patina due to airborne particles, weathering cycles and the mineralogy of the stone itself. Unlike surface dirt, the patina does not simply lie across the surface of the stone but is combined to varying depths within the masonry, be it stone, brick or terracotta. Although not necessarily damaging in itself great care must be undertaken if this is to be removed - inappropriate methods could destroy the original and weaken the substrate to decay or more commonly mobilising the minerals beneath the stone surface resulting in discoloration.

The Initial Survey

In order to assess the need for cleaning and prior to any recommendations Stone Restoration Services will complete a thorough survey. Our tender document will identify the material and any relevant factors which may have gone unnoticed (for example formulations of mortars, stone misstated on documentation) and any repairs, re-pointing, or visible damage.

In addition to the general criteria the context of the building itself, its history, construction, location and proximity to other buildings etc will also be borne in mind.The type of soiling /staining and best appropriate cleaning method will be detailed in our documentation and bill of quantities.

Stone Restoration Services are experienced in all different cleaning methods - there are positive and negative points to all methods and there is rarely a single method suitable for all situations. The least harmful method or combination of methods will be selected for each case. It is generally agreed that a sample area be carefully carried out on inconspicuous areas, to demonstrate the end result, for the client's consideration.

TORC torc logo

Stone Restoration Services are an approved TORC Contractor and own a number of systems. This ensures that any cleaning contract can be commenced and completed effectively and efficiently.

The Torc system is well recognised for its gentle yet effective swirling vortex cleaning using a mixture of low air pressure, a little water and a safe inert powder/material.The system also has the added advantage of water saving "stator" which also allow lower amounts of granulates required - thus eradicating the danger of over saturation of the substrate.

DOFF doff stone cleaning

The DOFF system should not be confused with other "hot water" systems - this system provides 'superheated' water (up to 150°C if necessary) that exits the nozzle, not just hot (70-90°), or steam.

The system uses a normal water supply which is taken into the high pressure pump unit and the pressure increased to the required level before entering the Hotbox.



doff cleaning

The desired pressure can be variably adjusted by the operator and is independent of temperature settings.

Within the heater unit, the temperature can be increased up to 150°C if necessary, before it passes through a heat resistant nozzle and onto the surface to be cleaned.


JOS DOFF Nebulous Spray

Nebulous spray - also known as intermittent mist spray - is a development of low-pressure water washing and is probably the least aggressive form of cleaning.

Water is passed through a very fine mesh or filter to create a mist that is then passed through fine nozzles. Its application is particularly useful where water-soluble dirt is present.The aim is to apply the minimum amount of water for the minimum duration to soften the dirt, thereby enabling its removal by agitating.

When using a the Nebulous Spray system, the level of water may be controlled electronically or by timers, allowing pulse or intermittent spraying, to avoid ever having water running down the face of the building. Before starting, the porosity of the stone can be assessed in order to balance the amount of water and duration required. By comparison low pressure water washing risks saturating the masonry which may cause corrosion of fixings or internal building damage.