How to remove black stains from Teracotta tiles?

[Gilbert]

Hi, I have been "googling" this for hours and am making no progress so any help appreciated! I laid some Parafeuille tiles (basically just teracotta tiles) about 5 years ago in our hallway and kitchen. When they were laid I sealed them with linseed oil and white spirit to stop any salts coming through. I noticed after a couple of years, however, that there were black spots appearing on the tiles by the front door and around the kitchen sink. I am thinking that this is where water has just sat on the surface of the tile. My memory isn't great these days, but I dont think I used any additional sealer when they were laid. Last year I tried to scrub out the black spots that had appeared and then applied some sealer. This has probably just sealed in the black spots (maybe a mould)?!

So what I am trying to work out is does any of this make any sense, and if so is there a product I should use to remove the black spots and then reseal so it doesnt happen again?

As you can probably tell I ain't no expert!

Thanks for any help you can provide

Gilbert

 

[Lithofin BOB]

Spore quite comman In Terracotta, where water has ingressed or migrated from a leak or such, if on the surface test a suitable mildew remover on one tile in a discreet area. , if it is below your linseed you may need to strip this back to then apply your product, leave 5-6 days after all this then re apply your oil or such.
Only one thing, if you select several tiles these can then stick out as cleaned tiles to the rest.

You said you originally oiled to stop salts, is this a very old floor? It may need to breath. Any photos noise spore and tile.

 

[Gilbert]

Spore quite comman In Terracotta, where water has ingressed or migrated from a leak or such, if on the surface test a suitable mildew remover on one tile in a discreet area. , if it is below your linseed you may need to strip this back to then apply your product, leave 5-6 days after all this then re apply your oil or such.
Only one thing, if you select several tiles these can then stick out as cleaned tiles to the rest.

You said you originally oiled to stop salts, is this a very old floor? It may need to breath. Any photos noise spore and tile.

Thanks for responding. The tiles are old internal roof tiles used in south of France and Spain but were only laid for first time 5 yrs ago. I think it probably is spore you mention and it's probably under the linseed. Would I need some form of acid to strip back do you think? Once stripped back any advice on spore cleaner and how I could stop it happening again? I am going to be at house in 2 weeks time so will post some pics. Have some spare tiles so if I damage them I can swop! Thanks again. Gilbert

 

[Lithofin BOB]

Hi < not acidic , i would test a solvent stripping agent on one tile to cut into the oil, we have wax off; as for the tile specific mildew remover , we have mildew away , others available.

 

[Jason-OTS]

Hi - There are a couple of options here you could simply try a product called LTP Mouldex I think it is around £8 -9 this is a Mould and algae remover and its good stuff suitable for terracotta - try it on a small area if they mould has not been sealed in it should get rid of it quickly alternatively it would be a case of stripping back and cleaning may be use something like LTP Power Stripper this will strip everything off and take it back to its original state - it would then be a case or re-sealing either with a traditional clear wax or Linseed Oil or the more synthetic route - Thing to be aware of is that whatever you do to just the tiles with the mould it is quite possible they are going to look cleaner than the rest of the floor - Good Luck