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Patio Black Spot Remover How to Removing Black Spots on Your Patio: A Comprehensive Guide

By Mark Cave March 07, 2024

Patio Black Spot Remover How to Removing Black Spots on Your Patio: A Comprehensive Guide

lots of black spots on a patio

Dealing with stubborn black spots on patios and Indian sandstone can be a frustrating task for many homeowners and cleaning professionals. These black spots are a type of lichen that embed themselves deeply into the substrate of hard surfaces, particularly those that haven't been treated with a softwashing solution for years. Notoriously difficult to remove, these blemishes can withstand even the most rigorous pressure washing, leaving many to wonder if a truly effective solution exists. Fortunately, there is a proven method for eliminating these pesky spots, using a combination of sodium hypochlorite and a surfactant like Clever Wash. In this post, we'll delve into how this blend works wonders on black spots and provide you with a step-by-step guide to achieving spotless outdoor surfaces.

Sodium Hypochlorite For Soft Washing 14% to 15%

Understanding Black Spots

Black spots are not just ordinary dirt or grime; they are lichens that have made themselves at home on your patio or stone surfaces. Lichens are symbiotic organisms composed of algae and fungi living together. Their roots can penetrate deep into porous surfaces like Indian sandstone, making them extremely difficult to remove through conventional cleaning methods, including pressure washing. Over time, these black spots not only detract from the appearance of your outdoor spaces but can also lead to further degradation of the surface if left untreated.

The Sodium Hypochlorite and Clever Wash Solution

The key to effective black spot removal lies in the use of sodium hypochlorite combined with a surfactant, such as Clever Wash. When blended together and diluted with the correct amount of water, this solution acts as a powerful agent against lichens, penetrating deep into the substrate and effectively killing the organisms responsible for black spots.

Clever Wash Softwash Surfactant

Sodium hypochlorite, commonly known as bleach, is a strong disinfectant that has been used for decades in various cleaning applications. However, when tackling black spots, its effectiveness is significantly enhanced by the addition of a surfactant. Clever Wash is designed to reduce the surface tension of the sodium hypochlorite solution, allowing it to penetrate more deeply into the lichens and ensuring a thorough kill.

Black spots cleaning on a patio

Step-by-Step Guide to Removing Black Spots

  1. Prepare the Solution: Mix one part sodium hypochlorite with three parts water. Depending on the size of the area you're treating and the container you're using for the mix, add approximately half a liter of Clever Wash surfactant to this blend.

  2. Apply to Affected Areas: Generously apply the solution to the black spots on your patio or stone surface. Ensure even coverage for optimal results.

  3. Wait and Observe: Allow the solution to dwell on the surface for at least 30 minutes. This gives the mixture ample time to penetrate the lichens and work its magic.

  4. Reapply if Necessary: If some stubborn black spots remain, reapply the solution as needed.

  5. Rinse Thoroughly: After the solution has done its job, rinse the area with a high-pressure turbo nozzle or a garden hose. This not only removes any dead lichens but also washes away residual chemicals, making the area safe for use.

  6. Safety Measures: If treating an enclosed area, wear a P3 rated mask and appropriate personal protective equipment, including gloves and coveralls. This protects you from potential chemical splashes and fumes.

Post-Treatment Care

While the sodium hypochlorite solution is highly effective at killing lichens, it may leave behind some residual crystals. These are harmless and will naturally dissipate within a day. However, if pets or people are likely to access the treated area soon after application, it's prudent to cordon off the area or rinse it down after treatment. This ensures that the space is safe and free from any chemical residues.

clean patio with no black spots

Pro Tip for Those Unsure About Mixing Chemicals

For individuals who might feel hesitant or unsure about mixing chemicals themselves, we've developed a convenient solution to address your concerns and still achieve exceptional cleaning results. Gel X Pro is our premixed solution designed to take the guesswork out of the process, ensuring you can safely and effectively treat surfaces without the need to handle raw chemicals.

Gel X Pro is incredibly versatile; while it's predominantly used for cleaning render, it's also highly effective at removing those stubborn black spots from patios and Indian sandstone. Its gel-like consistency ensures that it clings to the surfaces for longer dwell times, making it ideal for tackling more difficult stains.

Gel X Pro Black Spot Remover

For those instances where a lighter application is needed, Gel X Pro can easily be diluted to suit your specific cleaning requirements. This flexibility means you can adjust the strength of the solution depending on the severity of the dirt or staining you're facing.

We understand the importance of safety and ease of use, especially for DIY enthusiasts or those new to the world of softwashing. By choosing Gel X Pro, you're opting for a product that simplifies the cleaning process while still delivering professional-grade results.

Explore more about Gel X Pro and how it can transform your cleaning projects by visiting our website: Gel X Pro Render Cleaner

Whether you're tackling render, patios, or any other surface plagued by dirt, algae, or black spots, Gel X Pro offers a straightforward, effective solution. Say goodbye to the complications of mixing and measuring, and hello to effortlessly beautiful surfaces.

In Conclusion

Removing black spots from patios and Indian sandstone doesn't have to be an impossible task. With the right solution comprising sodium hypochlorite and Clever Wash, coupled with a bit of patience and the correct application technique, you can restore the beauty of your outdoor surfaces. Should you need further advice or support, Mark Cave at SoftWash UK is always available to answer any questions you may have. With the proper care and treatment, your patios and stone surfaces can remain spotless and welcoming for years to come.

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Soft Wash Calculator App

Now you can say I've got an app for that!


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Softwashing calculator is an indispensable tool for juggling complicated chemical mixes. It helps reduce wastage and keeps operating costs down by giving accurate proportions

If you are having difficulty getting your head around the maths, trying to work out what percentage of softwash you need, how much chemical, surfactant and water to add, then this is the App for you.



The Soft Wash Calculator App allows you to work out your soft wash recipe by telling you exactly how much chemical, how much water and how much surfactant to add to get the desired soft wash recipe.
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- works in both Litres and US Gallons
- tested for Protan and Deutan colourblind users
- links to SoftwashingUK website

Take this scenario
You started with a 1% soft wash recipe of 50 gal (or litres)  for a deck clean and you’re left with 13 gallons.

You get a call from a prospective customer to clean their roof. Past experience tells you a 4% soft wash recipe is needed, but what about your leftover mix at 1%?.

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You could consider the 13 gal as just water, top up the tank and start again.  
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Soft Wash Calculator App to the rescue.

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The same applies if you have a 4% recipe left in your tank and you need to dilute it down to 2%. Again the app will tell you how.

Softwashing calculator will also work for any chemical recipe. For instance you can use it for Sodium Hypochlorite, Bleach, Biocide , TFR traffic film remover and degreaser. Even the mathematically-challenged rocket scientist can top up their booster tanks to new fuel mixes after launch delays caused by changing weather conditions.

Using this app you will know exactly what chemical strength to put on any surface giving you the confidence and the knowledge of a professional soft washer and you’ll save money as well.

So if you have little knowledge of how to mix a soft wash recipe then this app is for you.
If you have little knowledge of how to remix a soft wash recipe then this app is for you.
If you want to save money when mixing a soft wash recipe then this app is for you.

This app is also backward compatible to devices running iOS7. We've done this so you can re-purpose an old iPhone 4 or iPod Touch 5  for what could be hazardous work environments. Just toss one in your cleaning van's toolkit.

Once you learn the methods and procedures of how to apply the soft wash to the different surfaces that need cleaning you’ll be unstoppable!

The app also has  a guide to what percentage for what surface. And if you are the lucky owner of a Clever Injector it will remind you the correct setting for the job.
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** A major iOS code-base change may require a re-purchase. The appiverse at the time will confirm our promise that we won't do so unless the necessity is apparent.



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