Atmospheric Pollution & General Grime
The slow, even dirtying that makes a building look tired without anyone noticing when it happened. Traffic film, carbon and, on the region's older stone, a hard sulphation crust left over from the industrial era.
This is the contaminant nobody reports. Graffiti gets a phone call within the hour; atmospheric soiling arrives over a decade and nobody can say when the building started looking tired. It just does, and then one day somebody cleans a section — behind a removed sign, say — and the contrast is a shock.
It's the most common reason buildings look neglected, and it's also the one that responds most dramatically to cleaning, because the material underneath is usually in perfectly good condition.
Ordinary grime versus industrial crust
There are two quite different things bundled under this heading, and telling them apart determines the whole job.
Modern traffic film and general grime is what accumulates now: exhaust particulates, brake dust, tyre rubber, general urban dirt. It sits on the surface and in the outer pores, held there by a slightly greasy binder from the hydrocarbons. It responds well to hot water, steam and mild detergent, and cleaning it is straightforward on most surfaces.
Sulphation crust is a legacy problem specific to older buildings in industrial regions, which describes a great deal of Greater Manchester. When coal smoke filled the air, sulphur dioxide reacted with calcium in stone and mortar to form gypsum, which crystallised at the surface and trapped soot inside it. The result is a hard black skin that is chemically part of the stone rather than sitting on it.
That crust doesn't wash off. It needs prolonged steam, chemical treatment or a poultice, and it's the reason cleaning a Victorian civic building is a different proposition from cleaning a 1990s office.
Look at where the black is. On most older buildings the crust is heaviest in sheltered areas — under copings, in reveals, behind columns — because rain has washed the exposed faces. That distinctive pattern of dark sheltered zones and lighter washed zones is the signature of sulphation rather than ordinary dirt.
Streaking and why it follows the same lines
Dirt on a building isn't random. It follows water, and water follows the details. Rain washes dirt off exposed surfaces and deposits it wherever the flow concentrates or stops, which is why the streaking on a facade is so consistent from one building to the next.
Dark tails below window sills mean the sill has no drip or a blocked one, so water runs back underneath and down the wall. Streaks below a coping or a string course mean the same thing at a larger scale. Vertical dark lines usually trace a leaking gutter joint or a hopper, and a fan of soiling near the ground is splashback.
Cleaning removes all of it. Whether it comes back in the same pattern within two years depends on whether anything was done about the detail that caused it. We photograph what we can see — missing drips, blocked hoppers, failed mastic — because a small repair alongside the clean is what makes the clean last.
Building looking tired and grey?
We'll clean a test panel so you can see what's underneath before committing to the whole elevation. Most buildings come up better than owners expect.
How clean should a building be?
A real question, not a rhetorical one, and it matters most on older stone. It's technically possible to clean a Victorian building back to something close to the colour of the quarry — and the result can look wrong: bright, raw and oddly new against neighbours that still carry their patina. Reaching that finish also requires the most aggressive treatment, which carries the most risk to the stone.
Most conservation officers prefer a gentle clean that removes disfiguring soiling and leaves the building's age readable. We'd generally agree. So on stone buildings we produce test panels at two or three intensities and let you choose by looking rather than describing.
On modern cladding, glass and rendered buildings the question doesn't really arise — those materials are meant to look clean, and cleaning them fully is exactly right.
Why regular cleaning costs less
Atmospheric soiling is the strongest argument in our trade for a cycle rather than an occasional rescue. It accumulates at a steady, predictable rate, and its behaviour changes with time in a way that matters financially.
Caught early it's a surface deposit that rinses off with hot water and mild detergent — quick, cheap and completely safe for the substrate. Left for fifteen years it bonds, and on stone it can chemically alter into something that needs poulticing. The same building costs several times more to clean and carries more risk to the material.
For commercial buildings, retail parks, business parks and school estates a planned programme — annual or biennial for most sites — is genuinely cheaper over a five or ten-year period than two deep cleans, and the building never goes through the years of looking neglected in between.
How To Recognise It
What it looks like
- Even grey-black soiling, heaviest on elevations facing traffic
- Dark streaking below sills, copings, string courses and any projection
- Hard black crust on sheltered areas of older stonework
- A clear contrast where a sheltered section has stayed lighter than the rest
What causes it
Dealing with the cause is what stops it coming back.
- Vehicle exhaust and brake dust, especially on busy urban corridors
- Historic coal-smoke deposits chemically bonded into the stone
- Rainwater run-off carrying dirt down predictable paths on the elevation
- Surface texture and porosity that give particulates somewhere to lodge
Frequently Asked Questions
Why is my building black on some parts and not others?
Because rain washes the exposed faces and can't reach the sheltered ones. On older stone buildings the black areas under copings, in reveals and behind columns are usually a sulphation crust — a hard deposit formed when industrial-era coal smoke reacted with the stone, trapping soot. It's chemically bonded rather than sitting on the surface, so it needs steam, chemical treatment or a poultice rather than washing.
Will cleaning make my building look brand new?
It can, and on stone that isn't always desirable. A fully cleaned Victorian building can look raw and out of place beside its neighbours, and reaching that finish needs the most aggressive treatment. We produce test panels at different intensities so you can see the options on your own building and choose.
Why does the dirt come back in the same streaks?
Because it follows water, and water follows the building's details. Streaks below sills, copings and hoppers point to a missing drip, a blockage or a failed joint. Cleaning removes the marks; fixing the detail is what stops them returning in the same lines within a couple of years. We photograph what we spot so you can decide.
How often should a commercial building be cleaned?
Annually or every two years for most, depending on exposure and how prominent the building is. Regular cleaning is significantly cheaper over time because the soiling never bonds — it rinses off with hot water rather than needing chemical treatment. It also means the building never spends years looking neglected between deep cleans.
Areas We Cover
We deal with atmospheric pollution & grime across Manchester, Greater Manchester and Cheshire, including:
Other Contaminants We Remove
Need graffiti gone — fast?
Call 0161 399 5247 or request a free quote. We respond within one working hour.