Cleaning block paving - how to wash it and what with

Everyday dirt and dust. A grey film, sand in the joints, darker tracks where you walk and drive most. It sits on the surface, so start by sweeping and washing with water and a brush. If the paving still looks dull and greyed, reach for the EC-87 paving cleaner - it refreshes block paving, concrete, clinker and stone and works in just 2-3 minutes. An old, greasy driveway comes clean with the alkaline concentrate D-12K for block paving.

Moss and green growth. Algae and moss grow where there is shade and damp: along a north wall, under a tree, in hollows where water stands. A cleaner for organic soiling takes the growth off, but if the conditions stay, it comes back after every wash. How to change that is covered in our guide to moss and green growth on paving.

Lime efflorescence. A white, matt bloom, most often on new paving. It is lime that water carried out of the concrete, so water and detergent will not touch it - only an acidic cleaner dissolves it. Where it comes from and whether it returns is explained in efflorescence on block paving.

Cement laitance. A grey haze, streaks and crumbs of mortar on the paving right after laying, bricklaying or cutting. It is building residue that has to come off before the first sealing. The guide how to remove cement laitance takes you through it step by step.

Oil and grease. A dark patch under the car, by the barbecue or in front of the garage. Oil soaks into the pores, so a brush does nothing and harder scrubbing only spreads it. Cover a fresh stain with sand, sawdust or cat litter first, then use a degreaser. The full order of work is in our guide to oil stains on paving and concrete.

Water and a brush. Enough for anything lying on the surface: dust, sand, leaves, mud. Sweeping away loose dirt is also the first step before any other treatment.

A pressure washer. It strips dirt and growth off paving in minutes, but it also washes the sand out of the joints, and on older paving it can damage the surface layer. An emptied joint holds moisture longer, which favours green growth. So keep the pressure down and top the joints up afterwards. Where a washer really earns its place is rinsing off cleaners - Guard Remover Eco and Net’Guard Ultra 4 in 1 are best rinsed off with one.

A cleaner. You need one when the soiling has bonded with the paving: efflorescence has come out of the concrete, laitance has hardened, oil has soaked into the pores. Water alone, even under pressure, will not do it here. Acidic cleaners dissolve mineral deposits - efflorescence, laitance and mortar residue - while alkaline ones deal with grease and organic dirt. You will find every cleaner in the cleaning and restoration category.

1. Sweep and protect the surroundings. Clear sand and leaves, and cover plants, metal edging and painted elements before you start. The acidic D-2W and D-2B must not touch metal, paint coatings or render.

2. Do a test. On coloured paving, try the cleaner on an inconspicuous spot first. Undiluted, the acidic EC-22 can draw out colour, so on coloured surfaces you dilute it with water.

3. Apply in the right conditions. Do not work in rain or on a surface heated by the sun. Take the dilution from the technical data: D-12K is diluted with water, most often 1:4, while Guard Remover Eco and Net’Guard Ultra are used undiluted.

4. Watch the dwell time. Never let the cleaner dry on the paving - it is the most common cause of streaks after washing. Guard Remover Eco stays on for 5 minutes at most, while Net’Guard Ultra needs 15 minutes or more, depending on the soiling.

5. Rinse thoroughly. With plenty of water, ideally with a pressure washer. If you have several problems at once, remove the grease first, then the mineral deposits, and rinse everything at the end.

If you plan to seal after washing, a clean surface matters twice over. A sealer soaks into the pores together with whatever is left in them and locks it in - bloom, grease or laitance then stay for years, and removing them means stripping the sealer. There is only one order: wash, rinse, dry, seal.

Not just the surface but the pores must be dry. New paving also needs time to give off its mixing water - with some sealers that is 28 days. Every condition is covered in our guide preparing the substrate before sealing, and once the surface is ready, see how to choose a block paving sealer. On new paving, a convenient first step is Guard Remover Eco, which needs no neutralising after rinsing.