This is my bathroom..initially for 1st 2 years no such patch..however it start appearing on this location 3 years ago..the patch start growing larger and larger. The tiles are homogeneous slate tiles.

Looks like soap scum to me, floor slope to this corner, so all dirt are accumulated in this area. try google to see how to remove them. You got dark tile, try on small area first.

Oh, I remember, my resale flat had this problem too. It happens on the area where water is trap, cannot flow. It feels like calcium deposit. like teeth tartars. What I did was to scrap them off, like what the dentist do. This is also a common occurence in old swimming pool.

When was the last time u give your bathroom a good wash? It looks like leftover soap scum to me

Thanks for all the replies. The area concerned is outside the shower area, where there is minimum contact with shower cream or soap. Bathroom clean once a week, but that yellow "deposit" is formed over 3 years. However I scrub or clean is no use...any chemical to intro?

This is the exterior of the shower screen?

Why does it look like there's water seeping out from beneath the kerb?

Does it feel rough and hard.

This is the exterior of the shower screen?

Why does it look like there's water seeping out from beneath the kerb?

Does it feel rough and hard.

Yup..it feels rough and hard..it could be water seeping out from side of the shower screen..but its minimal..

I googled and use baking soda to let it soak for 5mins before using a screw driver to scrape it off..here's the results..

I was gonna suggest making a paste by mixing baking soda with white vinegar, smear it on the area.

Let the solution penetrate the harden mineral deposits overnight to soften it, then scrap it off with some tool or metal gauze next day.

Seems like you got rid of it with just baking soda.

It's hardwater deposits aka lime scale if I'm not wrong.

But it seem to be seeping out from the bottom of the kerb rather than from the sides of the screen.

Edited June 28, 201016 yr by lawry

I was gonna suggest making a paste by mixing baking soda with white vinegar, smear it on the area.

Let the solution penetrate the harden mineral deposits overnight to soften it, then scrap it off with some tool or metal gauze next day.

Seems like you got rid of it with just baking soda.

It's hardwater deposits aka lime scale if I'm not wrong.

But it seem to be seeping out from the bottom of the kerb rather than from the sides of the screen.

I didn't add white vinegar..probably that explains why I only achieve 80% results..your idea is good, I'll try it overnight later.

Bro lawry..do you mean the water seeps from inside the kerb? Does it mean the water-proofing is not present?

It is normal to do water-proofing for kerbs? and also normal to do water-proofing to cover the whole wall tiles?

usually water proofing is only done for flooring with upturn at the sides for about 15cm. it may not be done over the kerb.

I didn't add white vinegar..probably that explains why I only achieve 80% results..your idea is good, I'll try it overnight later.

Bro lawry..do you mean the water seeps from inside the kerb? Does it mean the water-proofing is not present?

It is normal to do water-proofing for kerbs? and also normal to do water-proofing to cover the whole wall tiles?

- Soda is alkaline, vinegar is acidic, mix together will neutralise each other with some creamy foam +water.

- The residual can be easily brushed away after soaking with diluted acid for a few minutes. 1 bottle of diluted acide cost abt $2.

- Believed the bonding material that used to glue the kerb on top of tiles is the result of this residual.

- Some more the floor tiles with rought surfaces leave room for water to .....

- Normal washing powder is made of soda, mixed with different content, pure soda in white powder form need liciencing.

- Those transparent "washing cloth liquid" is actually diluted soda solution, you would feel hand slippery after touching it.

Edited June 29, 201016 yr by bepgof

- Soda is alkaline, vinegar is acidic, mix together will neutralise each other with some creamy foam +water.

- The residual can be easily brushed away after soaking with diluted acid for a few minutes. 1 bottle of diluted acide cost abt $2.

- Believed the bonding material that used to glue the kerb on top of tiles is the result of this residual.

- Some more the floor tiles with rought surfaces leave room for water to .....

- Normal washing powder is made of soda, mixed with different content, pure soda in white powder form need liciencing.

- Those transparent "washing cloth liquid" is actually diluted soda solution, you would feel hand slippery after touching it.

Ooops, you were right.

For the limescale

Alkaline solution - Baking soda + water to make a paste or

Acidic solution - Vinegar or Lemon juice

Baking soda + vinegar is for clearing clogged drainage.

When you add the 2 one after another followed by hot water, you get some nice bubbly chemical reaction, good for clearing pipes.

I didn't add white vinegar..probably that explains why I only achieve 80% results..your idea is good, I'll try it overnight later.

Bro lawry..do you mean the water seeps from inside the kerb? Does it mean the water-proofing is not present?

It is normal to do water-proofing for kerbs? and also normal to do water-proofing to cover the whole wall tiles?

Hi, I said that based on what I see in your photo. The limescale seems to be nicely formed just along the edges.

If it were from the sides of the shower screen, you would have limescale on your kerb as well.

But strangely, it's just along the edge.

No worry, this is still quite easy to remove with some non toxic household ingredients.

Ooops, you were right.

For the limescale

Alkaline solution - Baking soda + water to make a paste or

Acidic solution - Vinegar or Lemon juice

Baking soda + vinegar is for clearing clogged drainage.

When you add the 2 one after another followed by hot water, you get some nice bubbly chemical reaction, good for clearing pipes.

Hi, I said that based on what I see in your photo. The limescale seems to be nicely formed just along the edges.

If it were from the sides of the shower screen, you would have limescale on your kerb as well.

But strangely, it's just along the edge.

No worry, this is still quite easy to remove with some non toxic household ingredients.

Wah piang, I taught my secondary-school son how to mix baking soda & vinegar to simulate the effects of a erupting volcano in a school open house project , a month or 2 ago.

.

Wah piang, I taught my secondary-school son how to mix baking soda & vinegar to simulate the effects of a erupting volcano in a school open house project , a month or 2 ago.

.

Did it "erupt"?

usually water proofing is only done for flooring with upturn at the sides for about 15cm. it may not be done over the kerb.

I am sure they didn't do water-proofing for the kerb.

Reason I ask is because for the future..thought of doing water-proofing for whole bathroom, coz 15cm upturn at both side don't seem to be working well as I wash the wall tiles weekly, and the peeling and cracking 1 floor below my bathroom is very bad