Do water-repellent sealers help control biological growths?

May 28, 2015

Do water-repellent sealers help control biological growths?

Water repellent external sealers are sometimes used on stone, brick, roof tiles, and render in an attempt to increase the life of building materials. Brickwork and clay tiles for example, become porous after a few years, leading to the surface breaking up through the action of winter frost.

In our experience we've found no evidence that water repellent sealers inhibit the return of biological growths. In fact our experience of the products we've used is that they have no effect whatever.

Can sealers damage buildings?

Reducing the external porosity of a surface may lead to adverse effects on the inside of a building, in particular older buildings that are purposely designed to "breathe". Our experience suggests the wisdom of never using a non-breathable sealant, one that does not allow the building to breathe.

Sealants of this quality are not cheap but the potential long-term damage to a building by using an inferior, non-breathable product could be considerably more expensive.

Quick tip: Our experience suggests that even the best sealants will benefit from a supplementary pre-treatment with Benz Bio Cleanze softwash biocide.

Without a biocide treatment, even if the surface is cleaned before sealing by pressure washing, it will return to its “dirty” – i.e. biologically colonised – state shockingly quickly.

Whereas a property treated with Bio Cleanze – after giving a first treatment of Benz Lightning Cleanze biocide to rapidly kill the surface growths and clean the surface – and then sealed can remain clean for several years.

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).

Click here to download our Product Documentation Pack (includes Application & Dilution guides, SDS, PDS, RAMS, PPE & Mask info, COSSH, sample Contract and more)

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

Leave a comment

Comments will be approved before showing up. Please revisit to read our response.

Also in Benz Trade Tips

How to clean sh stains from lead flashing with Oxy Cleanze
How to clean sh stains from lead flashing with Oxy Cleanze

June 25, 2022

Sodium hypochlorite can react with lead flashing and discolour it. Benz Oxy Cleanze can fix this.

Click the link on this page to find out how ...

View full article →

When to pressure wash – and when not to pressure wash?
When to pressure wash – and when not to pressure wash?

June 17, 2022 4 Comments

After pressure washing (power, jet) algae spores rapidly recolonise, and properties return to square one in a very short time. So what's the alternative?

Click the link on this page to find out ...

View full article →

How long can I store diluted Benz Bio Cleanze (softwash ddac biocide)?
How long can I store diluted Bio Cleanze (softwash biocide)?

June 15, 2022 2 Comments

How long can diluted Benz Bio Cleanze can be stored for, and still be ok to use on another job?

Click the link on this page to find out ...

View full article →