White Stains on Exterior Porcelain Tiles

[lesterwilde]

Hi folks, Have had 600 x600 porcelain tiles laid onto well cured ecternal screed slab.

Tiles where sold as exterior grade. The have a rough texture to them.

screed slab had been down six months.

Slab had Ardex exterior leveling compound on top of slab before tiling. Ardex exterior adhesive and grouts have been used for laying tiles. Tiles have been laid about 2 weeks.

Tiles had some soil staining on surface had to be washed down with jet wash.

The problem is white staining has appeared in big areas over tiles. Is this the dreaded effervescence salts coming through.

Any suugestions on what can be done to sort this problem out would very much apprecaited.

Thanks Lester

 

[AliGage]

It looks suspiciously like it. What were the joints filled with? Have they been grouted?

 

[DHTiling]

A concrete slab can leach salts no matter how old it is... don't worry as it can be treated... but the down side is that it can return due to wetting which will cause the salts to migrate again..

Are the tiles a through bodied porcelain..?

 

[lesterwilde]

Dave,

Not sure if they where through bodied porcelain? Will check They have a textured finish, and where supplied as suitable for exterior use. So hopefully are.

How would you treat the stains?

Thankyou for your time and advise.

Regards

Lester

 

[DHTiling]

A diluted solution of brick acid... but as always try on a small area first.

 

[Tech]

Just my 2 pence worth but it might be grouting residue. Try using an acid wash on a single tile and see if this resolves the problem. You'll need to dilute the product with water as it works better diluted than it does neat. Scrub the tile with the solution with a hard brush, then after a couple of minutes rinse thoroughly with water.

My experience is predominantly interior tiling so not heard of the salt problem. By 99% of cleaning problems and white staining like this is due to grouting residue.

Final idea if this doesn't resolve it is to call someone like Fila Chemicals who have a technical department who'll give you some more advice!