I said I would be back talking about problems and issues with porcelain tiles and here I am. This won’t be the final chapter either. Having had yet another call today on ‘cloudy marks’ on newly laid porcelain floor tiles I thought should bring it up as a blog topic.So, what is the problem? An increasing number of porcelain manufacturers are applying coatings to their tiles at the factory. This practice is predominant (but not restricted to) manufacturers in China and some other Eastern countries. Basically there are several types of coating that can be applied, from easy to remove waxes, to much more stubborn wax-type coatings and now even new ‘nano’ sealers.
The reason that these coatings are applied is two-fold; firstly, it is applied to the face of the tiles to help prevent damage caused during transit; (with the tiles being stacked against each other, they can scratch). Secondly, it is intended to provide a small degree of protection on site.
The problem is that the coatings need to be removed before or after grouting, but certainly upon completion (depends on the coating). This is where the problem arises, as it is not always easy to remove, and, furthermore if it is not removed it will leave the tile looking, dull, patchy, cloudy or hazy. Sometimes it is so bad it looks like grout staining.
Some large retailers have had so many issues that they now (finally) tell their customers that there is a wax and that it should be removed, although they do not seem to be too proficient at telling them how to remove the coatings.
In general terms, most of these coatings are a wax and typically they need removing before grouting. Some professionals prefer to leave the wax on whilst grouting but I have seen many problems with this, although the wax can help, it does not always prevent staining from grout. The grouting process itself can partially remove the wax and this does two things:
1. It leaves a patchy, partial wax coating and,
2. It means some grouts, especially the pigmented ones, can now stain the unprotected areas of the tile. So, my preferred system would be as follows:
1. Lay tiles
2. Remove wax
3. Apply a good quality impregnating sealer
5. When completely cured, apply final coat of the same sealer (this way you make sure the tile is properly sealed, and chances are, if it was waxed, it is the type of porcelain that needs sealing – plus, you also seal the grout.)
Next time I’ll talk about ways to remove the wax and also about Nano sealer residue.Copyright Ian Taylor and The Tile and Stone Blog.co.uk, 2013. See copyright notice above.