Every now and then we get customers calling us for advice on how to remove grout haze from newly installed natural stone tiles. It’s quite frustrating as whoever has installed the tiles in the first place hasn’t followed standard installation protocol.
I’ve already discussed sealing natural stone tiles in a previous post. Basically, standard practice is to seal once before grouting (1 good coat) and once after grouting. You can seal twice before grouting if the tiles are quite porous like for example, Limestone Tiles. What this does, apart from protect your stone tiles during every day life, is help prevent grout sticking to the surface of the tile during installation. Natural stone tiles should be “point grouted” like a brick wall would be “pointed” so as to prevent grout from being smeared across the entire surface of the stone tiles. Surplus grout that gets onto the surface of the tile during grouting will dry out very quickly if the tiles are not sealed as the moisture from the wet grout is drawn into the surface of the tile and the grout then sticks to the tile. Sometimes you might just get a haze which can be cleaned quite easily. If the grout is left too long on the surface then heavy deposits may remain which are very hard to remove. This is why sealing stone tiles in advance of grouting stops the grout drying out too quickly allowing the installer to simply wipe it off. Once the grout between the joints has dried properly, the tiles can be cleaned thoroughly with water or a light duty “residue remover” ready for their second coat. If the tiles aren’t cleaned properly and sealer is applied over grout haze, this just makes the whole thing worse.
The main culprit for issues like this is definitely limestone tiles especially white limestone tiles like our Mediterranean white limestone or the Applestone Limestone tiles as they are quite porous and suck the water out of grout very quickly. Travertine Tiles can also have issues but they are less porous and more forgiving. Marble Tiles and Granite Tiles tend not to suffer from these issues as they aren’t as porous but it’s still better to follow the sealer protocol as detailed above. If however you find yourself in the unfortunate situation where your installer has either forgotten to seal first, didn’t know that’s what they had to do or just couldn’t be bothered and your beautiful limestone bathroom tiles are covered in haze then all is not lost. Depending on the severity, you can use a light duty residue remover available at places like Topps etc. This is a liquid you mix with water and scrub on to remove grout haze - fairly straight forward.
If you have heavier deposits then you may need a “heavy duty residue remover” which is basically a mild acid. Be careful though as this can damage the surface of your natural stone tiles if it’s used neat. Again, mix with water and scrub on, but don’t allow to dry. You need to wipe off before the tiles dry with a damp sponge. Full instructions are of course on the bottles and we highly recommend you read them and discuss them with whoever you buy it from. You may need to repeat the process a few times until it’s all gone. We do not recommend the use of any abrasive products like wet and dry paper or scotch pads, unless you really know what you are doing. These can ruin your tiles if used incorrectly. A good stiff old fashioned scrubbing brush is the best option with some elbow grease.
There are a few of us here at stonesuperstore.co.uk that has experience in all aspects like this. If you would like any clarification or advice then why not call the office. So to surmise, always make sure the tiles, especially limestone tiles, are sealed properly before grouting, and cleaned properly before sealing after grouting. Many hours of heartache and hassle can be avoided if you make sure this simple procedure is followed.