DOFF Cleaning vs Sandblasting.
Two very different tools that get lumped together. Here's how each one actually works, and how we decide which your building needs.
- Specialist-trained operators
- Method-matched to your surface
What DOFF (Superheated Steam) Cleaning Actually Is
DOFF is a brand name for a superheated water system — water delivered at the nozzle at temperatures up to around 150°C but at very low pressure, typically well under the pressure of a domestic jet wash. The heat, not the force, does the cleaning: it softens carbon soiling, sulfation crusts, moss, algae, lichen and many paints so they release from the surface. Because there is no abrasive media and very little water volume, the masonry stays essentially dry and the stone face is untouched. Biological growth is killed at the root rather than just stripped, so regrowth is slower.
What Sandblasting Actually Is
Abrasive blasting fires graded media — garnet, olivine, glass, or sodium bicarbonate for soft work — at the surface under air pressure. It removes material mechanically. That is exactly what you want on rusted structural steel, cast-iron railings, heavy coatings, and hard industrial brick: it cuts through the layer and leaves a keyed profile ready for paint. The same action on soft Victorian brick strips the fired outer skin, and on weathered sandstone it takes millimetres off the face. Neither can be put back.
Side by Side
Pressure & Contact
Best For
Waste & Mess
Speed & Cost
How We Choose Between Them
We survey the substrate first — stone type, brick hardness, condition of the pointing, what the soiling actually is, and the listing or conservation-area status. Then we run a small test patch in an inconspicuous spot and show you the result before agreeing the method for the whole elevation. On mixed buildings we frequently use both: superheated steam on the sandstone dressings and a gentle graded abrasive on the ironwork or the rear yard brickwork. Being method-matched rather than one-tool is the whole point.
Warning Signs in a Quote
A quote that never names the method, quotes one rate per square metre regardless of substrate, or offers to "sandblast" a listed sandstone frontage should be treated with caution. Ask which method, what media, what pressure, and to see a test patch. Any specialist will answer without hesitation.
Related
See heritage & listed building cleaning, is sandblasting safe for old brick and stone, sandblasting costs, or our FAQ hub.
Frequently Asked Questions
Is DOFF cleaning better than sandblasting?
Neither is better in the abstract — they solve different problems. DOFF-style superheated steam is better on historic stone, listed brick and biological growth, because nothing abrasive touches the face. Dry abrasive blasting is better on structural steel, ironwork, thick coatings and hard engineering brick, where you need to cut through a tough layer and key the surface for paint.
Does DOFF damage stone?
Used correctly, no. It runs at low pressure with a wide nozzle; the heat does the work, not force. The risks are operator error — holding the nozzle too close, dwelling in one spot, or using it on badly delaminating stone that needs consolidation first. That is why we survey before we spec.
Is superheated steam cleaning suitable for listed buildings?
It is the method conservation officers most often accept, because it is water-only, non-abrasive and leaves no residue or chemical. We still provide a written method statement and a test patch for sign-off before full works.
Which method removes paint and graffiti?
Superheated steam plus a poultice or gel handles most masonry paint and graffiti on historic surfaces. Heavy multi-layer industrial coatings on steel or hard brick are faster and cheaper with a graded abrasive.
Which costs more?
Per square metre, steam-based cleaning is usually slower and therefore dearer than open abrasive blasting, but it avoids the repair, repointing and consolidation bills that a badly blasted facade generates. On heritage work it is almost always the cheaper outcome.
Not sure which method your building needs?
Send us a couple of photos and a postcode. We'll come out, survey the property, and put a written price in your hand within days — not weeks.