Hirst Conservation & Materials Limited : :

Hirst Conservation offer a variety of specialist cleaning processes for the removal of dirt, grime and paint from historic buildings and stonework due to pollution, vandalism or fire & water damage. Where necessary, we will utilise several different systems to overcome any localised variations that may be discovered on a building façade. With our expertise in other aspects of building conservation, combined with the development and support of our technical division, this enables Hirst Conservation to provide a complete and professional service for the cleaning of any historic buildings.

The 3 main processes utilised by Hirst Conservation are the JOS system, the DOFF system and the KRAKE system.

The JOS system is essentially a wet, mild jet abrasive cleaning system, made suitable for conservation applications by a controllable low pressure vortex of air, water and granulate, swirling almost parallel to the surface. This swirling action cleans away unwanted matter more carefully than conventional right-angle impact systems. It is chemical-free and environmentally friendly.

The system has a controllable, very low air pressure (7-21psi) rotational vortex, carrying small quantities of water (30-60 litres per hour) plus very fine neutral granular particles. This ensures that dust and slurry levels are kept to an absolute minimum. The nature of the JOS system means that it can be employed for use on extremely delicate areas such as intricate carvings and mouldings. Experience has shown that this system is unsurpassed in it's effectiveness and controllability when used for the removal of black sulphate skin form limestone.

A normal water supply is taken into the high pressure pump and the pressure is increased to the appropriate level before it enters the hot-box where if necessary, the temperature is increased up to a level of 150°C. This is then fed through high pressure heat resistant hoses to the nozzle. Special jets efficiently directed to the surface cut through and remove unwanted matter.

The ability to maintain high temperatures and low pressure is a particularly special feature of the DOFF system. However, simultaneous high pressure and high temperature can be introduced if necessary for the removal of paint and other heavy coatings. Heating of the surface is controlled and will be dry in minutes. Depending upon the requirements of the system, a range of appropriate lances and nozzles are available - please contact us for advice on specific applications.

The KRAKE system is invaluable in situations where water spillage is problematic or undesirable and the use of open-jetting is not an option. The system enables the benefits of water cleaning to be utilised whilst completely containing the water and leaving the substrate dry to the touch.

The system must be used with pumping equipment. For example, it can be used with a standard cold water pressure washer or a hot water system such as the DOFF. It can also be used at standard mains pressure direct from the domestic tap system if light rinsing is required.