The Right Way to Clean Stonework: Why We Use the DOFF System

Stonework is built to last — but only if it’s treated with care. When it comes to cleaning stone, especially on heritage or older buildings, the wrong method can do more harm than good. That’s why at Salthouse Stonemasonry, we trust the DOFF system — and here’s why you should too.

🔍 What Is the DOFF System?

The DOFF system is a specialist steam-based cleaning tool designed specifically for delicate masonry. It works by producing superheated water (up to 150°C) at low pressure. That combination — high heat, low force — is what makes it uniquely gentle but effective.

💥 Why Pressure Washing and Harsh Chemicals Don’t Belong on Stone

We’ve seen too many cases where well-meaning property owners or contractors have used:

• High-pressure washers

• Abrasive pads or sandblasting

• Off-the-shelf acidic or bleach-based cleaners

These methods can:

• Strip away protective surface layers

• Force water deep into the stone, risking long-term damage

• Accelerate decay, delamination, or salt bloom

• Destroy historic patina and detail

Stone isn’t just rock — it breathes, it reacts to moisture, and it can be surprisingly fragile. Cleaning it like you would a driveway is a fast track to irreversible damage.

✅ The DOFF Difference

Here’s why we swear by the DOFF system:

• Gentle but powerful: It lifts dirt, biological growth, pollution, and even paint without eroding the surface.

• No harsh chemicals needed: Ideal for conservation areas or eco-conscious clients.

• Dry finish: The superheated steam evaporates almost instantly, reducing saturation and drying time.

• Approved for listed buildings: It’s the go-to system for English Heritage and Historic England for a reason.

🏠 When Should You Clean Your Stone?

Not all stonework needs cleaning — and over-cleaning can actually wear it down. But if you’re seeing:

• Algae, moss, or lichen

• Pollution staining or soot

• Graffiti

• Paint remnants

...then it’s worth a professional assessment to see if a DOFF clean is appropriate.

🛠 Our Approach at Salthouse Stonemasonry

We don’t just turn up with a machine. Every job starts with a stone assessment — we match the cleaning method to the material, location, and condition of the stone. No guesswork. No corner-cutting. Just careful, conservation-grade cleaning.

🐝 Want Your Stonework Treated with Respect?

If you're considering stone cleaning, don’t take risks with your building’s future. Reach out to us at Salthouse Stonemasonry — we’ll restore your stone the right way.