Weather it is sanded, un sanded or epoxy grout can be recoloured.
But first you will need to check a few things before grout recolouring.
- What level is your grout? Before grout recolouring, your grout needs to be recessed below the tile. Flush grout cannot be colour sealed. You will not be able to apply a grout colourant as it will wipe off during the application process. Also the grout colouring can wear off due to foot traffic. You can try and score the grout down but this procedure makes grout look rough not smooth and like painting anything that has a rough surface will not look good.
- Grout inspection? Missing grout, holes or cracks in grout all needs to be repaired before a grout colouring can be applied. If your grout is missing in certain areas then replacing the grout is the only option. Missing grout can be due to movement in the substrate therefore the grout may fall out again. To fix hair line cracks or small holes in grout simply use unsanded grout. If your grout has larger cracks or holes then we recommend using sanded grout. Once grout has been fixed wait 48 hours before applying our grout colourant.
- Grout hardness? Soft grout cannot be colour sealed. To test this, simply use a pocket knife and press hard into your grout. You should not be able to get through hardened grout. If your knife does goes into the grout then it is too soft to colour seal and replacement is recommended. The reasons for soft grout are due to grout that has gone off before installing. All grout mixes are powdery but off grout will be rock hard and you will have to break the grout up to a powdery consistency.
- Grout Cleanliness!
All grout that has been installed for over 6 months will become soiled by foot traffic, dust and from general cleaning. Grout has to be free of dirt and grease so the grout colouring can bond properly to the grouts surface. Grout should be cleaned with a high alkaline pH 12 cleaner and grout brush. If grout is older than 10 years then an acid cleaner pH 1 should be used after using an alkaline cleaner. You will notice once the acid cleaner is applied to cleaned grout it will fizz and turn white. This will determine two factors that it is a cement grout and free of any topical soils, coatings or waxes. You can be assured that your grout colourant sealer will bond perfectly.
- Has your grout been sealed before?
As mentioned above, grout needs to be free of any contamination; this includes grout sealers that may have been previously applied. If you have sealed your grout before then we need to test again to see if we can get a reaction from an acid cleaner. If you can get a reaction from an acid cleaner then you will good to go in applying a grout colourant. If no reaction then this can affect the bonding of a grout colourant. Another issue is what type of grout sealer may have been used. Natural look grout sealers also known as penetrating sealers that have been applied some time ago are ok and an acid reaction should be seen. The other grout sealer is topical coatings also known as wet look or shiny sealers. There will need to be removed using a stripper and grout brush. Once your done removing the topical grout sealer we recommend using a high pH 12 grout cleaner followed by an acid cleaner.