Indian sandstone is one of the most popular paving materials. It’s easy to see why. It looks sublime in both traditional and modern gardens due to its rustic finish, earthy tones, depth of character and versatility.
However, like all natural stone, it’s not immune to heavy footfall, spring showers and winter frosts, which means regular TLC is essential to keep it looking fresh.
Without taking the proper maintenance measures, Indian sandstone is susceptible to discolouration and decay. The severity of the deterioration depends on time, use, the type of foliage nearby and the proximity of the stone to water.
Thankfully, there’s no need to stress! Cleaning Indian sandstone is straightforward and requires little effort - a simple wash-down with soapy water eradicates everyday grime while a diluted bleach formula tackles stubborn stains, moss and algae.
In this post, we’ll guide you through cleaning Indian sandstone in eight simple steps.
What you’ll need
- Acid-free soap or bleach
- Special iron-free fungicide for lichen removal
- Bucket and water
- Stiff brush or broom for scrubbing
- Watering can or hose
- Potentially a power washer (more on this later)
- A bit of elbow grease (it’s time to work up a sweat)
- Kettle on boil (because tea makes everything better)
1. Identify the problem
The materials required for cleaning Indian sandstone depend on what’s causing the discolouration and the seriousness of the spread, so it makes sense to identify exactly what’s wrong before creating a plan of action.
If your sandstone looks dirty, it’s probably down to everyday use and it’s easily rectified. More serious problems include green blemishes and grimy spots that grow over time.
- Green fuzz over the whole slab is usually caused by algae.
- Green borders are a result of moss growing in the dirt between the slabs.
- Patches that get larger over time are caused by lichen (a colony of fungus and algae and/or cyanobacteria - by far the most challenging issue to deal with).
2. Choose the solution
Before we talk about what solution to choose, let’s discuss what not to use.
To preserve your sandstone, avoid using acid-based cleaning products or solutions that contain iron. They’ll only lead to rust and more heartache. Plus, harsh chemicals promising to remove fungus could discolour the sandstone permanently.
Luckily, you don’t need any of these fancy potions to clean Indian sandstone. For common grime, the simplest and safest remedy is good old soapy water (washing-up liquid does the trick), and to tackle more stubborn problems (algae, moss and lichens) use diluted bleach.
If the lichens don’t respond to bleach and a good scrub, you might require additional support in the form of specially designed, iron-free fungicides.
If you’re using soapy water, add enough soap for the mixture to become frothy. With bleach solutions, dilute the bleach with equal parts of water.
3. Pour the mixture
After creating the solution, remove nearby furniture, sweep the affected area and pour the mixture onto your slabs.
Leave it to sit for 15-30 minutes (longer is better for more extreme build-ups) to give the chemicals enough time to loosen surface debris.
4. Put some muscle in
After you’ve drenched the stone and had a well-deserved cuppa, it’s time to put some muscle in.
Grab a stiff broom and scrub the stone, paying special attention to corners, gaps and borders. For lichen removal, it’s best to use a wire brush and spend a bit more time going over the affected areas.
A word of warning – take care with the amount of pressure you apply as overzealous brushing could damage the sandstone.
If you’re using bleach, wait another 15 minutes before rinsing.
5. Rinse and repeat
Wash away the loosened dirt with clean water, using a bucket, watering can or hose (low-pressure).
In most cases, you can now put your feet up - your work is done. However, for more stubborn problems, repeat the above steps two to three times over several weeks.
6. Consider a power washer
A power washer is an excellent alternative for cleaning Indian sandstone and especially helpful if you have large areas to treat. However, you must find the right pressure setting because sandstone is relatively soft, and a powerful stream could erode some of the stone along with the contaminants.
To avoid damage, choose a low-setting and wash diagonally across the slabs rather than parallel to the joints. You might need to repeat the process several times to ensure the area is thoroughly clean.
7. Take precautionary action
The best defence is a good offence, so adhere to the following measures to prevent future build-ups and infections.
- Get proactive and regularly brush your sandstone to disturb weeds, dirt and microorganisms before they take hold.
- Invest in a quality sealant. When properly applied, sealant improves your paving's durability by protecting the jointing and eradicating the damp conditions moss, algae and fungi love so much.
- Remove nearby water features and think about repositioning plants.
- Repeat the above steps every two to three months, even if there's no noticeable grime - this will help catch any invisible threats before it's too late.
You made it! We told you it wasn’t too hard. You should now have sandstone that looks as good as new, free from unsightly muck.
The last thing to do, after your paving area is dry, is to reintroduce plants, garden furniture and people – because it’s time to show off the fruits of your labour.
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