Oil & Grease Removal

Oil is the contaminant that most often gets made worse by a well-intentioned clean. It's the instinctive response — point a pressure washer at the dark patch — and it's precisely wrong. Water and oil don't mix, so the jet doesn't lift the oil; it drives it sideways and deeper. You end up with a larger, paler stain and the satisfaction of having done something.

Removing oil properly means changing its chemistry first so that it can be carried away by water. That's what a degreaser does, and it needs time on the surface to work. The rinse is the last step, not the method.

Why it goes in rather than sitting on top

Concrete, block paving and unsealed masonry are porous, and oil is thin and persistent. A leak drips onto the same spot day after day, and each drop wicks a little further into the pore structure. After a couple of years the contamination can be several millimetres deep, and what you see on the surface is the smallest part of it.

That's why oil stains reappear. A surface clean lifts what's on the face, the slab looks good for a fortnight, and then oil held deeper migrates back up and the patch returns. Nothing has failed — the clean simply never reached most of the contamination.

Tarmac is a special case and a worse one. Bitumen is itself a petroleum product, so engine oil doesn't just sit in the surface, it dissolves the binder. Long-standing oil patches on tarmac often feel slightly soft, and the material around them deteriorates and ravels. That damage isn't a cleaning problem at all.

How we actually remove it

For anything that has been soaking in for years, the poultice is the step that does the real work. An absorbent paste carrying a solvent is applied thickly and left; as it dries it pulls moisture and dissolved oil upwards out of the slab. Two or three applications on a bad patch is normal. It's slow, but it's the only approach that removes contamination rather than redistributing it.

• Identify the oil — engine oil, diesel, hydraulic fluid and cooking grease respond to different products
• Apply an appropriate degreaser and give it real dwell time to emulsify the oil
• Agitate mechanically so the product reaches into the surface texture
• Hot rinse — heat matters far more than pressure with grease
• Poultice for deep contamination, drawing oil back out over hours or days
• Contain and dispose of run-off correctly — this is oily water, not grey water

Run-off is a legal issue, not just good manners

Cleaning oil produces oily water, and where that goes matters. Most car parks and yards drain to surface water systems that discharge to a watercourse — and around Greater Manchester a great many of those discharge into the canal network or the Irwell and Mersey catchments. Allowing contaminated run-off into them is a pollution offence, and it's the site operator who tends to be on the receiving end of the enquiry.

So before we start we establish which gullies are foul and which are surface water, whether there's an interceptor and whether it's been maintained. Depending on the answer we bund, mat, divert or vacuum-recover, and on sensitive sites we capture the water entirely for proper disposal.

It's the part of the job that quotes most often omit, and it's worth asking any contractor about — including us.

Kitchen and bin store grease

A different flavour of the same problem, and a common one on retail, hospitality and multi-site estates. Grease around a bin store or a kitchen extract is a hygiene issue as much as an appearance one — it attracts vermin, it smells, and it's exactly what an environmental health visit picks up on.

This work is usually alkaline degreaser, hot water and a sanitising treatment afterwards, done frequently rather than thoroughly-once. Grease near a food premises accumulates fast, so a monthly or quarterly cycle keeps it under control far more effectively than an annual deep clean, and it's much less disruptive to the business.

Because these areas are usually enclosed and near food, product choice and rinsing discipline matter. Our multi-site retail and hospitality clients typically have this on a standing cycle across their estate.

What to expect

Fresh spills come out fully. Contamination that's a few months old comes out well. Years-old staining in porous concrete improves dramatically but may keep a shadow, because some of the oil has gone deeper than any poultice will reach.

Where a single bay is severely contaminated, replacing a handful of paving blocks can genuinely be cheaper than repeated treatment, and we'll say so rather than quoting three visits. On tarmac that has softened, the honest answer is a localised repair rather than a clean.

We'd rather set that out at survey than have a client expect a slab that looks new. Most oil work delivers a very obvious improvement; complete erasure of a decade-old stain sometimes isn't available at any price.