The Science of Steam: Superheated Water vs. High Pressure
Standard jet washing relies on high hydraulic pressure to blast away surface dirt. On historic Scottish sandstone, terracotta, or delicate brickwork, high pressure strips away the protective outer skin of the stone, blows out breathable mortar joints, and forces excess moisture deep into wall cavities.
The DOFF System works on a fundamentally different principle: extreme temperature paired with low pressure. Water is heated up to 150°C in a specialized diesel-fired boiler before being delivered through a heat-resistant nozzle at a gentle, controllable pressure.
Key Technical Specifications
- 150°C Superheated Temperature: Vaporises heavy biological growth, moss, oil, wax, and paint coatings on contact.
- Low-Pressure Delivery: Operates at minimal pressure to prevent micro-fracturing, stone surface erosion, or substrate pitting.
- Rapid Drying Time: High thermal energy causes water to evaporate rapidly, preventing deep saturation and freeze-thaw damage.
What Can DOFF Cleaning Remove?
- Biological Growth & Spores: The 150°C heat sanitizes moss, lichen, algae spores, and fungi down to the roots without requiring toxic chemical washes.
- Paints & Masonry Coatings: Softens and lifts historic non-breathable oil paints, plasticized masonry paints, graffiti, and elastomeric coatings.
- Bitumen, Wax & Resins: Melts away stubborn industrial residues, bitumen damp-proof coatings, grease, wax, and chewing gum cleanly.
- Carbon Crusts & Urban Grime: Breaks down decades of atmospheric pollution, traffic soot, and airborne particulates from urban building facades.
- Heavy Algae & Biofilms: Clears aggressive red algae (Trentepohlia) and black spot spores from delicate render, stone, and tile surfaces.
- Efflorescence & Salts: Gently dissolves ground salts and surface efflorescence deposits without driving moisture deeper into the wall structure.
Approved for Listed Buildings & Heritage Sites
Because DOFF cleaning uses pure water without abrasive aggregates or harsh chemicals, it is universally recognized and specified by heritage bodies across the UK, including Historic Environment Scotland and conservation architects.