How to soft wash natural and man-made stone

April 03, 2019

How to soft wash natural and man-made stone

Benz Bio Cleanze, Perma Cleanze, Lightning Cleanze and Tornado Cleanze are all suitable for cleaning natural stone, man-made stone, hard stone and soft stone.

We sell two softwash biocides: Bio Cleanze and Lightning Cleanze.

Benz Tornado Cleanze, acts as a "residual spot cleaner" which removes any remaining ingrained black, green, red and yellow staining (caused by algae, lichen, moss and mould) from stone, concrete, brickwork, uPVC and most other external hard surfaces.

Tornado Cleanze is particularly valuable for the softwash cleaning of vertical stone walls when you need a product that with "super-stickability" that will cling to the surface and not run off.


Click here to download our Product Documentation Pack – which contains all the information you need – including SDS, PDS, dilution rates and application methods. – for all our softwash products.

The photo below shows the versatility of Bio Cleanze (30:1 after 4 months) when soft washing wall render, a concrete kerb and stone chippings



On the whole, for non-porous hard stone such as granite, you’ll find Lightning Cleanze and Tornado Cleanze produce the fastest and most effective results. And they are highly effective when used together in a "perfect synergistic partnership".

For soft, porous stone such as sandstone, Benz Bio Cleanze comes into it’s own as a post-treatment because it’s extremely good “wetting” characteristics – it's an even more effective wetting agent than water – allow it to soak deep down under the surface.

This enables Bio Cleanze to kill any remaining spores that may have remained deep within the permeable stone. It can also be used as a stand-alone treatment for hard stone such as granite. And it offers longer-term residual protection from re-colonisation than is possible when soft washing with a sodium hypochlorite product alone.

Soft wash cleaning of black limestone

Black limestone can fade over time through exposure to weathering by sun and rain. It can become covered in algae which, when treated, exposes the faded limestone underneath the colonisation. And because of it's susceptibility to weathering, exposed areas of limestone can look dramatically different to sheltered areas.

Limestone often contains iron, which can turn black or orange and look unsightly. Sometimes limestone can look worse after soft washing. Fortunately, over time the limestone will usually fade back to how it looked before being treated. 

Other factors to consider when soft wash cleaning limestone:

  • How the limestone slabs were laid, e.g. if laid on "dabs" of cement this can show up as dark/light patches on the surface of the slabs.
  • What the limestone slabs are laid on (eg concrete, sand, gravel, earth) will affect what the top surface looks like.
  • The quality of drainage determines what limestone slabs look like, particularly if drainage is poor.
  • A limestone path or patio may look different during a long, hot dry spell in summer compared to how it looks in the middle of winter.

Quick tip: As with any surface and product you are not 100% certain will be compatible, always (with your customer's permission) treat a small, out of the way test area first.

Giving stone a soft wash re-treatment

A stone surface – whether natural stone or man-made stone, hard stone or soft stone – should not require re-treating for several months after being cleaned with Lightning Cleanze or Tornado Cleanze.

The time after which re-treatment with Bio Cleanze will become necessary is far greater, although because of the numerous variable factors it is impossible to quote a definite period.

The exact time-scale depends on the type of stone, the local environment, the care that your customer takes of their property, and the proximity of trees, bushes, plant pots, etc.

Quick tip: After the first treatment, remember to put your customer onto an ongoing scheduled "Clean & Maintain" programme, which will keep your customers happy by giving them a permanently clean property – and give you, the contractor, a nice repeat income.

We hope this information is helpful and sincerely wish you great success in your soft washing business,

Ben, Leo, Fiona, Stevie & Anthony

Click here to get more practical soft washing how-to tips

How to find answers to most soft washing questions: Simply enter a relevant "keyword" or short phrase – e.g. keyword for the above link = "how-to" – into our in-site Search Engine (magnifying glass icon on the main menu).

Order Benz Softwash chemicals & equipment online or by phone:

GB (England, Scotland, Wales)

Phone: 0800 70 74 222 


Ireland and other countries

Phone: 00353 214 622 978


Lines open Monday - Friday, 9am – 5pm

Please note: The above numbers are for orders only (click here for tech support)

PS: Click here to set up your "Clean & Maintain" programme
. After completing an initial soft wash treatment, put your customer on a "Clean & Maintain" ongoing maintenance programme. Your customers will enjoy a permanently clean property and you will enjoy a steady stream of repeat business.

This is clearly a win-win arrangement for you and your customers.


Click here to explore the extensive range of Benz softwash cleaning chemicals & equipment

Benz Softwash Bio Cleanze DDAC biocide & Benz Softwash Lightning Cleanze SH sodium hypochlorite biocide

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