removing limescale from outdoor tiles

[Kenny202]

Have some shiny ceramic (porcelain?) white tiles on the verandah outside. One of those areas that collects water and in the shade / sun. They are large white shiny tiles like you would have inside. In a few areas there is a greenish coating on them which is quite hard and stubborn. After soaking in pure bleach for 30 minutes and then a good scrubbing, I got stuck into it today with a steel pot scrubber and did remove it from a small area but was a lot of work for little return. Nearly something you need the angle grinder on! The good news is it looks like what ever it is hasn't permeated the tiles. I thought maybe an acid based thing is needed? Its going to need a lot more than a soak in bleach or vinegar. The bleach did very little to remove or loosen it up. Lots of products on Lazada but its been scam city lately, I throw more products in the bin / return than I keep and 100s of reviews is no guarantee these days.

 

Can someone recommend a HD cleaner or what sort of ingredients I need to look for in a HD outdoor tile cleaner?

[UWEB]

27 minutes ago, Kenny202 said:

Have some shiny ceramic (porcelain?) white tiles on the verandah outside. One of those areas that collects water and in the shade / sun. They are large white shiny tiles like you would have inside. In a few areas there is a greenish coating on them which is quite hard and stubborn. After soaking in pure bleach for 30 minutes and then a good scrubbing, I got stuck into it today with a steel pot scrubber and did remove it from a small area but was a lot of work for little return. Nearly something you need the angle grinder on! The good news is it looks like what ever it is hasn't permeated the tiles. I thought maybe an acid based thing is needed? Its going to need a lot more than a soak in bleach or vinegar. The bleach did very little to remove or loosen it up. Lots of products on Lazada but its been scam city lately, I throw more products in the bin / return than I keep and 100s of reviews is no guarantee these days.

 

Can someone recommend a HD cleaner or what sort of ingredients I need to look for in a HD outdoor tile cleaner?

I'm using always for such kind of cleaning some of my Pool Acid mixed with Water 10:1. You have to work in small sections and not leave the Acid on longer then 2 Minutes and clean it with clear Water. If still some left I repeat it again.

[Kenny202]

16 hours ago, UWEB said:

I'm using always for such kind of cleaning some of my Pool Acid mixed with Water 10:1. You have to work in small sections and not leave the Acid on longer then 2 Minutes and clean it with clear Water. If still some left I repeat it again.

Thanks for the reply....pool acid is hydrochloric right?

[UWEB]

1 hour ago, Kenny202 said:

Thanks for the reply....pool acid is hydrochloric right?

Yes, Hydrochloride Acid 34%.

[Pogust]

Phosphoric acid is commonly used to dissolve lime scale. Available on Lazada. Dilute to 10-20%. Good in bathroom if you have that problem.

[NorthernRyland]

14 minutes ago, Pogust said:

Phosphoric acid is commonly used to dissolve lime scale. Available on Lazada. Dilute to 10-20%. Good in bathroom if you have that problem.

I have hard water where I live and if it's not too thick vinegar takes it off. I should get that acid though probably. Thanks for the tip.

[Sheryl]

Vinegar or lemon juice  will do it but problem is it may run off, and at least  few hours contact is necessary.

 

In which case  2 approaches:

 

1. Soak paper towel in vinegar and cover the tile with wet towel. .Rewet periodically.

 

Or

 

2. Mix vinegar with cream of tartar into a thin paste, apply that.

 

In both cases keep the vinegar applied several hours, then scrub.

 

Never use bleach for this as bleach is a base, and   you need acids to dissolve limescale. 

 

 

 

 

[alanrchase]

Just buy some toilet cleaner. ARO brand in Makro is 22% hydrochloric acid. Make sure you dilute it as at 22% it melts Scotchbrite. Vixol is a name brand at about 11% and Tesco had their own brand at about 14% I think.

 

 

[xtrnuno41]

Dont forget HCl 34 % is "smoking" , pure HCl is coming out !

Dont inhale , as your lungs can handle it and you can go down, with burned lungs.

Dont put on skin or worse in eyes.

Very hygroscopic leaving burn marks on skin and very possible not ever be able to see anymore if in eyes.

Dont put water to the HCl, an exotherm reaction will occur and it gets real hot, to boiling, splashing the liquid around, ON YOU.

Can solve calcium very good, but be aware how to handle !

 

[RocketDog]

On 2/18/2025 at 3:43 PM, UWEB said:

I'm using always for such kind of cleaning some of my Pool Acid mixed with Water 10:1. You have to work in small sections and not leave the Acid on longer then 2 Minutes and clean it with clear Water. If still some left I repeat it again.

Pool acid is HCl usually 35%. As you say delete and wear a mask and goggles when pouring and using. Add acid to water, not reverse.

 

I razor blade scraper will help on glazed tile after the acid dissolves some of it.

 

Greenish color is not calcium carbonate the OP describes.