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Home | How to remove efflorescence from floors, walls & patios

How to remove efflorescence from floors, walls & patios
How to remove efflorescence from floors, walls & patios

Nov 1, 2022

How to remove efflorescence from floors, walls & patios

If you wish to remove efflorescence salting, we recommend using Floorseal Efflorescence Remover. Please read on for our handy tips!

The removal of efflorescence is normally easy, particularly when it has recently appeared. But it can be complicated by the length of time it has been present and the type of surface it has appeared on.

Efflorescence salting can be mistaken for other issues which affect exterior surfaces, we will discuss this later in the article.

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how to remove efflorescence from floors, walls patios

What is efflorescence?

Efflorescence is just a salt left behind as moisture slowly evaporates from the surface. It may appear just after a patio is laid, a wall built or repointed. Salting may also appear after deep cleaning a very porous surface.

Efflorescence sometimes appears on old floors due to the lack of a DPM (damp-proof membrane). Or on old interior walls where the wall is rubble filled, so no cavity is present.

Efflorescence can just be a general white patchy powder, a white bleed mark or can almost look like a fur/mould (when severe) on interior surfaces.

How easy is it to remove efflorescence?

In general, it is easy to remove newly formed efflorescence. Sometimes, after removal, it can return if the drying process is not complete. It is still worth removing efflorescence even if you know it might return, the reasons for this will be discussed later in the article.

How to remove efflorescence from patios, driveways & paths

The first method people will try to remove efflorescence is to pressure wash the efflorescence away, which can work. The issue is that the addition of very large quantities of water can trigger more efflorescence.

New patios can display efflorescence which simply runs its course over time. It may have to be removed a number of times but eventually never returns. If the patio was laid late in the year, the salting may not appear until spring.

The application of Floorseal Efflorescence Remover will react with the salting and dissolve it. After use always rinse the solution away with clean water.

This method can be followed on sandstones, slate, porcelain, and granite. It is also suitable for use on clay-based materials such as bricks, quarry tile and terracotta.

You should not use the remover on acid sensitive surfaces like limestone, travertine, marble & cement-based tiles. It may be possible to use the product on rough concrete (with care).

Always test in an inconspicuous place and allow test area to dry before proceeding to full application.

Efflorescence 'salting' is a common problem on brick walls in the UK

How to remove Efflorescence from exterior walls

On exterior walls, pressure washing the efflorescence may have some effect. The issue is that the addition of lots of water can either trigger more efflorescence, so the powder simply returns.

Normally the application of Efflorescence Remover will remove the salting. You will still need to lightly rinse the area after use.

Rinsing is important as salts can be redistributed over the surface unless they are fully removed. The efflorescence salting will be suspended in the cleaning solution so must be at least lightly rinsed away.

If, for instance, the exterior wall has a soil banking behind, the moisture may constantly bleed through the wall and therefore always leave a salt behind. The only process is to remove the efflorescence periodically so the salt does not become calcified. If the salt chemically hardens and calcifies it may not be possible to remove it via a cleaning agent.

How to remove efflorescence on interior walls

The same method can be followed on interior walls with lighter rinsing. Treating the wall in small patches by use of a paintbrush, then blotting the Efflorescence Remover away with absorbent cloths, is sensible.

Again, rinsing is important as the salt could be redistributed over the surface unless removed. The salts will be suspended in the cleaning solution so might be redeposited over the surface. This can be avoided by rinsing and blottting the wall with cloths.

Interior walls may suffer from efflorescence if they are naturally damp. Or if the exterior pointing has failed leading to damp within the building.

Sometimes salting is noted if an interior brick or stone wall has just been exposed, possibly after being hidden behind plaster. Modern plaster can trap moisture between it and the wall, once removed the wall dries slowly leaving a salt.

Removing the efflorescence is wise to prevent it from chemically hardening, but it may return if the root of the issue has not been resolved.

If the wall was damp and the underlying issue is later resolved you might find you can remove the efflorescence and it never returns.

Interior Efflorescence staining is often considered a worse problem than external marking

Is efflorescence ever NOT possible to remove?

It can be impossible to remove efflorescence when it has calcified. This occurs when efflorescence has been present for years (or sometimes only months) and chemically hardens.

Once this has happened any liquid treatment employed to remove the efflorescence may react with just the top layers. But will ultimately fail to remove anything beyond this.

Calcified efflorescence usually needs an abrasive technique to remove it. This could be diamond pads fitted under floor machines. Or media blasting for exterior walls – but this subject/method of removal is beyond the scope of this article.

Are there situations where efflorescence might be mistaken for other issues?

Yes, this frequently occurs on newly laid natural stone patios!

If a patio has been laid and sealed with a surface sealer please note the points below.

  1. You may trap moisture under the surface sealer (which is trying to escape through the stone/pointing from the base as it naturally dries). In other words, the patio has been sealed too soon or is laid on damp ground generally.
  2. The surface sealer may have been applied & encountered moisture from rain/dew/frost before it has cured. The sealer may look dry but if it has not cured (or the sealer has been overapplied) moisture may become trapped in the microscopic air bubbles forming in the sealant as it cures.

Trapped moisture looks like white or grey patches all over the stone. In other words, it looks a little like efflorescence. In actual fact, it’s moisture trapped under or within the sealer.

Customers commonly misdiagnose trapped moisture for efflorescence by ‘googling it’. Trapped moisture can look like images found on the internet of efflorescence salting.

Efflorescence on newly laid patios is reasonably common so it is quite an easy error to make. This misdiagnosis leads to confusion when a product used for the removal of efflorescence produces no reaction.

If you have efflorescence salting, Efflorescence Remover will react – if there is no reaction you are not dealing with efflorescence.

If you have trapped moisture under a topical/surface sealer you would probably need to strip the sealer to remove unsightly patches. Stripping sealers is beyond the scope of this article – and is hard work! Generally, once a failed surface sealer is removed the customer usually sees the merits of breathable impregnating sealers. These are a type of sealer which cannot trap mosture.

Remove efflorescence from natural stone tiles can take numerous attempts

When should I NOT use an efflorescence remover?

You should NOT use efflorescence removers on acid-sensitive surfaces, such as limestone, basalt, marble, travertine, terrazzo, cement-based tiles, cement-based block pavers or fine/smooth concretes.

Conclusion

Floorseal Efflorescence Remover is used for the removal of fresh or powdery efflorescence salting on sandstones, slate, clay bricks, porcelains, ceramics, Victorian tiles, quarry tile, terracotta and other acid-resistant surfaces.

Efflorescence Remover can be applied diluted from 1:3 with water to being applied neat. Coverage is approximately 8m2 per litre.

Please note, coverage will ultimately be determined by the porosity of the surface and level of contamination.

Calcified or age-hardened thickened salts may NOT be possible to remove other than via a mechanical method i.e blasting/abrasion

Always test before use on offcuts or in an inconspicuous place.

If you wish to view our other handy ‘how to guides’ please click here.

The information contained within this article is not exhaustive. If you need further information please contact Floorseal on (01484) 861461 or email us Info@floorseal.co.uk our web address is www.floorseal.co.uk

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