Sandstone paving is one of the most popular types of paving stones in the UK and Ireland, but over time it can lose its colour. This is where sandstone sealers come into play!
Sandstone sealers have a number of different functions – they provide protection from UV rays, repel water, stop weeds growing through and much more.
In this blog post we’ll discuss 5 types of sandstone sealer: their pros, cons and best uses.
What is sandstone paving sealer?
Sandstone sealers are a type of protective coating that is applied to sandstone paving. They give protection from UV rays, repel water and stop weeds growing through the spaces in between stones or blocks.
Sandstones have naturally high levels of iron oxide which can wear away over time due to exposure to rain and wind.
Sealers help keep the soluble iron oxide and other minerals, which are an integral part of the sandstone material, making up much to the beautiful colours.
Many sandstone sealants use a silicone polymer as their base. This is the main ingredient that protects from water and dirt penetrating through to the surface, which can then cause discoloration or staining..
Should you seal your sandstone paving?
It’s important to state that you don’t need to seal your sandstone paving.
Sandstone is naturally weather resistance and when it’s cleaned regularly, it should remain as such for a long time.
However, sealing your sandstone paving can have many benefits: like protecting the colour of the stone from fading; stopping weeds growing through to create an even surface; repelling water away so stones don’t become slippery in winter etc.
However before you jump in and buy some sealant you should be aware of the potential downsides to sealing your sandstone paving.
We have seen some disasters when sealing paving with the wrong type of sealants.
Types of sealant
There are many different types of sandstone paving sealant around so we have found the most useful way to break them down is by their uses. There are a few reasons that you may want to seal your sandstone paving:
– To protect the natural colour of your sandstone paving
– To stop weeds growing through and ruining a neat surface, or to create an even level for laying decking etc.
– As water repellent so stones don’t get slippery in winter time (usually used on exterior applications)
– To prevent staining from dirt, rust or general use
So lets dive into the different types of sealant and the best use for each.
Colour enhancing sealants
One of the best reasons to seal your paving is to enhance the beautiful natural colours of the paving which can become dull over time or simply not reach their full potential.
Colouring sealants give the paving more of a wet look, which generally intensifies the natural colours.
They also allow you to control just how much the colour is altered so that you can get the look you are after.
When used on exterior applications, colour enhance sealants will help prevent staining from dirt and rust as well as add water repellence which helps in winter time when pavements become slippery due to snow meltwater etc.
Weather protecting sealants
If you are using the paving outside its can be helpful to use a sealant which will protect the paving from the weather.
Water can make the stone slippery but can also penetrate the stone and allow algae and lichen to grow.
This is because the stone has a porous surface and when water gets in it can be trapped inside which will degrade the quality of the paving over time.
Many weather sealants also have colour enhancing properties so you do not need two different products for protection and enhancement, just one!
If you are using a water resistant sealant be warned that it can make the sandstone take longer to drain which can cause pooling. If your paving already had poor drainage we would advise against using this type of sealant.
Algae and fungi are the most common invaders of paving and will grow where there is moisture. They are slippery, ugly and over time can damage your sandstone paving.
Fungicidal sealants can be used to help with this as they contain fungicides which are designed to kill off the fungi, even if its in a dormant state. If you have any trouble with algae or lichen then it may be worth looking at using these sealers instead.
Stone impregnating sealants work by penetrating the surface of a stone, entering it and changing it on the surface layer and the layers below.
They tend to be more suitable for colour enhancement as they make the stone look very deep and rich. They are usually less substantial than surface sealers and don’t tend to last as long.
Stone sealers or coatings
Sealers and coatings create a layer on the surface of a stone which prevents anything from penetrating it.
These are more suitable for preventing things like algae and lichen to grow on your pavement as they block all access but also make the sandstone look very clean and fresh.
Surface coatings can offer the best protection, colour enhancement and modification to your paving. They also tend to have a longer lifespan.
Sounds like surface coating sealers are the way to go right? We don’t think so.
With their good properties comes an amazing ability to mess up your paving. Unless you get the right sealer, test it then apply it correctly there is a good chance you will end up ruining your paving.
This can’t be undone without some serious damage to the paving.
We recommend avoiding surface coatings unless your paving really needs it. Its just not worth the risk of messing up your nice new paving.
How to apply sandstone sealer
Rollers are usually the go to when you want a fairly even coverage on the stone. They’re easy to use and will deliver an even finish with very little effort
A paintbrush is great for small areas of sandstone that need impregnating or sealing but it can be a bit time consuming as you have to apply lots of coats evenly.
A sprayer is great for large areas of sandstone and will deliver a thicker, more even coat to the surface. It’s also easier as you don’t have to worry about applying it evenly or in small sections but be careful not to overdo it!
Apply with caution
Once you have applied a sealant it is nearly impossible to remove without causing damage to the surface and making it look faded. Always test the sealant on a small area of the stone to check that it doesn’t cause any discolouration or damage.
Make sure you properly clean and dry your paving before application.
Removing sealant from sandstone
If you want to remove the sealant then this can only be done with a very abrasive tool such as a wire brush.
The removal of any sealer will leave the pavement looking faded and dull so think carefully before removing any that has been applied
Temperature needed to apply sandstone sealant
If it is too cold the sealants may not cure properly which can either make them ineffective or look terrible.
If the weather is too hot it could cure too fast making application difficult and meaning that some areas end up looking patchy as the sealer didn’t have time to soak in or settle before it cured.
Typically, sandstone paving sealants need around 13-23 degrees Celsius to chemically react and set properly.
How long do sealants last?
There will be wide variation in how long each type last but it is typically between 12 and 18 months.
The main factors that affect the length of time a sealant lasts are:
– The amount of foot traffic it gets (more people walking on an area will wear down the sandstone paving)
– Temperature (if raised then this speeds up deterioration)
– The chosen sealant (some can last up to 5 years)
You sealants will probably need redoing at around the same time as the paving joint compound used between the paving slabs so it can be a good idea to do them both together.
In conclusion, sealers are a good way to protect your sandstone paving from potential damage which may be caused by weathering or physical contact with plants or animals. They also help keep it looking shiny for longer periods of time as well as keeping its colour intact.
However we don’t recommend using sealants due to the risk of them messing up your paving’s natural look.
If you can get away with just cleaning the paving then this would be the best option for most people.
If your paving is particularly prone to moss or algae, or is looking old and tired then sealants could be a good way to go. Just make sure you test before you apply!
For professionally installed paving and sealing in Preston and Lancashire, see our paving installation service.
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