Best practices for soft wash cleaning sandstone

September 03, 2019

Benz Tornado Cleanze for softwashing sandstone paths, patios and walls

Since introducing our powerful Tornado Cleanze thick gel cleaning product we've received many questions about it's use and application, in particular how to use it to softwash sandstone.


Here are our best suggestions for soft washing sandstone with Tornado Cleanze

1. Apply liberally and leave Tornado Cleanze for the recommended full 30 minutes activation time on porous surfaces, like sandstone.

Quick tip: On non-porous surfaces such as industrial cladding you will see results in less than 10 minutes, even when the product is greatly diluted. Experience will inform you how to approach the various materials and local conditions, and what dilution of Tornado Cleanze to use.

2. Use a medium soft brush to brush-in Tornado Cleanze. A 9 inch brush can be useful for awkward areas. Sometimes, for heavy black lichen for example, you may find a stiffer brush useful.

3. DO NOT, ever, use high pressure washing on sandstone. This will damage the surface layer of the stone, and if live growths are present will rip out the roots, further damaging the soft stone.

4. Give the sandstone a very light, low pressure, jet wash prior to treating with Tornado Cleanze. This is to remove loose matter from the surface, remove some of the more shallow-rooted growths, and will remove some of the skin from the remaining growths. Pre-cleaning the sandstone like this will allow Tornado Cleanze to penetrate more deeply more quickly, giving faster, more effective results.

Quick tip: Set your jet washer to very low pressure if you have a variable control, and/or fit with a fan jet and hold well back from the surface.

5. The light jet wash will also serve to pre-wet the surface, which makes application of Tornado Cleanze easier, quicker and more effective.

Quick tip: We've found that a light jet wash is more effective than sweeping the surface clean of loose matter, or using a blower.

6. Sandstone can be slower to come clean than hard stone like granite. This is why "less ethical" contractors employ high pressure washing and high concentrations of SH – so they can quickly produce a "Wow!" result that impresses customers who know no better.

In their pursuit of a fast buck they ignore the damage they do to their customer's property and the damage that long-term chlorine exposure does to their, and their employees, lungs. They rarely get repeat business ...

7. Complete the treatment of sandstone with an application of Benz Bio Cleanze (50:1 if children & animals will walk on it soon after treatment, otherwise can be up to 20:1 dilution).

Determine the strength at which to use Bio Cleanze by assessing factors such as a) how long since the sandstone was last cleaned b) how bad the colonisation of the sandstone is c) the local environment in which the sandstone lives.

Quick tip: Bio Cleanze will continue to deep clean porous surfaces such as sandstone over a period of several months, up to a year.

And of course it supplies residual protection against re-colonisation that neither jet washing nor any SH product/mix is able to offer.

Quick tip: Click here to learn more about the Benz "Clean & Maintain" softwash systems

Customers are often amazed, and very happy, when they watch the cleaning effect of Bio Cleanze continuing through time. And then they are even happier when they see how it dramatically slows down the tendency for a porous surface such as sandstone to re-colonise.

We hope this information is helpful.


Ben, Leo & Fiona


Leave a comment

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

Also in Benz Trade Tips

Great news for GB (England, Scotland, Wales) soft washing contractors
Great news for GB (England, Scotland, Wales) soft washing contractors!

January 18, 2022

GB customers can now checkout directly in £GBP. To make your life easier and simpler, we've created a website just for soft washing contractors in England, Scotland and Wales.

Click the link on this page to learn more and visit

View full article →

How to run a soft washing business in cold winter weather
How to run a soft washing business in cold winter weather

January 12, 2022

Soft washing can be carried out all year round when the temperature is not freezing or near freezing. The main thing to consider is that softwash chemicals will take longer to produce their full effect in cold conditions.

Click the link on this page to learn how to stay in business through a cold winter ...

View full article →

Do you know the best time of year to softwash concrete paths & patios?
Do you know the best time of year to softwash concrete paths & patios?

January 05, 2022

One of the nuances of soft washing when maintaining previously cleaned horizontal surfaces – concrete paths and patios in particular – and keeping them clean all year round,  is the occasional flare up of green algae.

Click the link on this page to learn how to deal with green algae flare-up ...

View full article →