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How to clean an exposed internal brick or masonry wall

How to clean an exposed internal brick or masonry wall

How do you clean dirty brick walls or masonry feature walls?

Are you trying to remove cement staining or lime hazes? Or are you trying to remove general dirt, grime, oils, and waxes? Ingrained soot around old fireplaces is common, it can be problematic when attempting to remove it completely.

The following information has some handy tips for cleaning interior brick & masonry walls prior to sealing.

Firstly, we recommend brushing down and dry vacuuming all surfaces. You may be able to flick or scrape off any obvious loose chunks of mortar, plaster or loose brick.

How do you clean an interior exposed brick wall?

How do you clean an interior exposed brick wall

To remove the general haze, dust or staining from:

  • Portland cement-based pointing
  • Lime-based pointing
  • Or cement and lime-based plaster

You should use Floorseal Cement & Grout Haze Remover.

This will dissolve the residue from dirt, grime, wax, cements, lime plaster, lime, and grout. This product can be applied neat or diluted in clean water. It will not react with non-acid sensitive surfaces such as sandstone, slate, and clay-based brick etc.

This product should not be used on a wall which is totally constructed from an acid-sensitive stone like limestone.

You can perform a small test to check if the surface is acid sensitive. If the surface appears to fizz or an obvious lighter halo is left by the product (when it dries) it may well be an acid-sensitive surface.

Red brick, slate, granite, flints, and sandstones are not acid sensitive.

Please be aware that a surface which is not acid sensitive can still fizz (a little) if there is a contamination of Portland cement, lime, and cement-based grout on the surface. This is quite common when an old lime plaster has been pulled away from the wall. This hazing is usually the very reason for cleaning in the first place!

Cement & Grout Haze Remover can be used to remove pointing stains and hazes; even when the wall has been pointed with a cement or a lime-based pointing. Always perform a small test! You will not adversely affect the pointing if you are careful. Apply a weaker solution, agitate with a brush, and wash down with water. You can also use a wet vacuum fitted with a circular (bristle head) upholstery brush to extract any rinse water.

Cement & Grout Haze Remover can be used in a diluted form or neat depending on the level of contamination encountered.

Removing general dirt and grime from a brick or masonry wall

Cement & Grout Haze Remover can be used to clean up stone hearths, general brick, and masonry.

This product is effective on light soot, dirt, oils as well as background contaminations of cement, mortar, lime, grout & concrete. 

Please note that if it is possible to wet clean the wall with just water and a stiff brush, you may be able to make a significant improvement!

Cleaning sandblasted surfaces and soot

How do you clean an interior exposed brick wall

Sandblasted surfaces have been completely resurfaced so do not need cleaning with a cleaning solution or chemical. Therefore, you should not need to carry out any intensive pre-cleaning work before sealing.

We strongly recommend brushing down the wall and vacuuming to remove loose fine dust.

Soot or carbon deposits which have become heavily embedded usually cannot be totally removed. If sandblasting has not already removed carbon deposits, wet cleaning will not.

Carbon deposits which have formed over 150 years will be so deeply embedded they cannot be removed by sandblasting or wet cleaning. This is usually not an issue as it is part of the character of an old building. It can be an issue if it is the result of a recent chimney fire or carbon deposits in a modern house.

You will be able to remove light and recent deposits of soot, oils and waxes with Floorseal Cement & Grout Haze Remover.  

What kind of tools might I need to clean an interior brick or masonry wall?

  • Stiff hand brushes
  • A wire brush (use with care)
  • A dry vacuum (possibly a wet vacuum if you have access to one)
  • Lots of cloths and masking material
  • Buckets/water
  • Eye protection, gloves, mask, and general PPE

How do you clean an interior exposed brick wall

Cleaning an interior brick wall is usually labour intensive – It can be slow going and will not produce the same clinical finish as sandblasting. However, sandblasting is not always required and is often not possible due to the level of dust produced! Many brick or masonry surfaces may just need a brush down before sealing with some work to remove dirt, grime and cement hazing.


Further information


Please Click Here to view our products & accessories for cleaning and sealing brick, natural stone or general masonry. This includes our handy ‘how to’ guides for sealing and cleaning interior and exterior brick, stone or masonry.

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