Blackened window sills and capping stones - do you know how to soft wash them?

November 18, 2021

Benz Tornado Cleanze & Benz Lightning Cleanze - for cleaning window sills and capping stones colonised by algae

Soft washing heavily blackened stone and concrete window sills and wall capping stones can be challenging and requires skilful application of the correct soft wash products. 

Quick tip: Usually the blackening is caused by a colonisation of black algae. But check that it is caused by black algae and not carbon from road traffic and aircraft, which requires different specialist treatment. 

In our experience the most effective way to clean blackened window sills, window surrounds, and wall capping stones is to first spray treat with Benz Lightning Cleanze biocide (4:1). This will kill the black algae and sanitise the surface. Then follow up by brushing in, usually neat, Benz Tornado Cleanze.

This is an example of the type of cleaning contract we created Tornado Cleanze for. Simply apply neat with a brush, or sometimes, if the colonisation is minimal, dilute up to 50%. The activation time needed will depend on the severity of the colonisation and the local temperature.

Quick tips:

1) Rinse well prior to giving a post-treatment with Benz Bio Cleanze.

2) And protect any plants or lawns that could come into contact with the rinse water.

Click here to get more practical soft washing how-to tips about cleaning with Tornado Cleanze

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

You can 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)

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

Ben, Leo, Fiona, Stevie & Anthony

PS: After completing the first 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 both customer and contractor.


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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