Preparing tiles for silicone - TilersForums.com

[Bloodoo]

After some 18 months much of the the silicone has let go from where my cut tiles meet the shower tray. From what I have gleaned from this forum I am beginning to suspect that the professional tiler did not seal the cut edges of the tiles before applying silicone...
I have cut out the old silicone and intend to clean all accessible surfaces with methylated spirit before re-applying silicone. Ideally I would like to apply tile sealer to the cut tile edges but the gap is less than two mm in places. I plan to use wet and dry paper on a blade on the cut tile edges and after final cleaning, force tile and stone sealer on a brush into the gap between tiles and shower tray. Will the tile sealer damage the tray? Given the the narrow space, can anyone suggest a better way to clean and seal the cut edges of the tiles?

 

[Sean Kelly]

In my opinion the problem is that your tiler did not use a 'solvent free' silicone. I can only presume that your tile is a natural stone, as you are trying to seal it with a stone sealer? You need to use a solvent free silicone such as Mapesil LM. This silicone is used for natural stone tiles. Other (or acetoxy) silicones could damage/stain your stone and or just peel away.

There is no need to seal the cut edge of your tile. Just make sure it is dry.
Buy a solvent free sealer.
Apply sealer to the area. Do not use water or spray.
If possible use a profiling tool to create a nice smooth finish.
Leave to cure.

Good luck.

 

[Bloodoo]

Sean,
Many thanks for your reply and guidance.
The back of a spare tile reads "Porcelain GP, made in Turkey". I presume the advice you have given for stone tiles holds good for porcelain as well.
Thank you once again

 

[Sean Kelly]

Ahh, this does make a difference.
Just buy a quality silicone. It does not have to be a solvent free one.

I've just noticed I called the silicone a 'sealer' in my previous post. I meant silicone.

Only some porcelain tiles need sealing. Some are pre sealed or nano sealed. It is normal to have the instructions on the box or on a leaflet within the box. If your tiles are polished porcelain and there are no instructions on the box then it would be wise to seal them with an impregnating sealer like Lithofin Stain stop.

 

[Bloodoo]

Thank you Sean, much appreciated.
The tiles are a matt finish. From what you say, I think I will try to treat the cut edge with a sealer as a precaution and hopefully get better adhesion for the silicone

 

[Sean Kelly]

Now I know all the facts.

You have a matt finish porcelain tile. Your tiler has cut the bottom row of tiles to fit around your shower (normal practice).
Believe me, you do not need to seal the cut underneath of the tile. The sealer will not be absorbed by your tile as porcelain is virtually impervious to liquids. It will be like trying to seal a sheet of glass.

We sometimes have to seal the top surface of a polished porcelain tile because if you looked at the top of a polished porcelain tile you will see tiny pits (caused by the polishing process). Grout can get caught in these pits which will turn your polished porcelain tiles into cloudy hazy tiles (not good).

 

[Bloodoo]

That's reassuring to know Sean, as I can do without the hassle of getting sealer into the narrow space between tiles and tray.
Thanks again