How to remove white deposits on tile joints?

[CarlL]

Hi all, 

My blockwall was tiled around two years ago and tiles (porcelain) were not grouted. 

I have noticed that there is some white deposits building up on the joints and spilling onto my letterbox. I tried to remove them mechanically with a plastic scraper without success. 

I believe this white residue is something related to the tile adhesive but not sure whether this is caused by the storm water which gets into the gap between tiles and blockwall (gap not sealed) and results in some sort of chemical reactions.

Anyone have any ideas about what the white deposits are and how to get rid of them?

TIA

gap btw tile and blockwall

[MitchellMc]

Hi @CarlL,

What you’re seeing is called efflorescence. It’s basically a white, powdery deposit that forms when water moves through masonry or adhesive and brings soluble salts to the surface. Once the water evaporates, it leaves those salts behind, which is what you’re noticing on your tile joints and letterbox.

Since you mentioned there’s a gap at the top where water can get in, that’s likely the main cause. I’d recommend sealing that gap to stop water entering — something like Sikaflex 11FC in Grey would be a good choice because it’s flexible, durable, and will match in reasonably well.

To try to remove the current marks, a scrubbing brush with some warm soapy water is a good first step. Efflorescence can sometimes be stubborn, but this gentler approach avoids damaging your tiles. There are chemical efflorescence removers available, but they’re quite harsh and typically designed for bare masonry like bricks rather than finished tile work, so I’d be cautious with those. 

Please let me know if you have any questions.

Mitchell

[CarlL]

Thank you so much @MitchellMc for the advice and tips.