What’s this stain?

[mnahmnah]

Hi

We moved into our house a few weeks ago. The hearth had a doormat covering this stain and I can’t work out what it is from and if we can do anything to rectify it? It’s an electric fire, not gas.

Any ideas? Thanks!

It looks like what happens to outside tiles when minerals rise to the surface in the sun, after being wet.

You can get cleaner for this so I wonder if this would work?

It looks like salt leach (Efflorescence). I'm guessing they are actually formed concrete patio tiles rather than stone ? Cheap but prone to this when they get wet.

Looks like salt leaching out to me too.

If they are actually stone then it's probably mortar leach, same thing (Efflorescence). It must have been left very wet at some point. Check your chimney has a good hat on it if that is an old fireplace - because it could be caused by water coming down the old chimney?

Might just be the heat from the fire bringing up the salts. Or a combination of heat and damp from washing them. Can you change them?

If it's just on the surface you might be able to sand them off slightly?

You don’t need to do this, just keep cleaning op, it stops eventually.

Don't do this if they are formed concrete tiles ! The colour is never consistent throughout the mix so you might get permenent lighter patches.

Thanks for the ideas.

Not sure what kind of stone they are, but it is rough to the touch.

We’ve already had a roofer up at the chimney and it’s completely blocked off.

If I want to try cleaning it off, what should I use?

Have you tried just soapy water?

@Janieforever

Not yet because until yesterday the Christmas tree was covering it and I’m just working out what to do. I will try that first!

Well scrubbed it last night with fairy liquid soapy water and it looks a bit better this morning. Might do the same again and see if that works!

Oh that's a better picture. Those are definitely not stone tiles. They are moulded concrete patio slabs 😞

You could just put some more tiles over the top, like a proper hearth? It’s a bit of a bodge at the moment, the tiles don’t seem to be grouted, or maybe that’s just the angle? That would be a shorterm fix.
I would think these are very cold and not easy to clean, they are not really meant for internal use.

Ah ok, they are outdoor tiles, same happened to me when we had the path relaid. The good news is it does go away, the bad news is you will need to keep cleaning it till all the salt has come to the surface.

Well the previous owner was a DIY enthusiast and there are plenty of dodgy jobs! Makes sense. Thanks!

you could paint them?

Efflorescence- salt leaching coming up after laying tile or concrete. Very easy to remove. Dilute 1/10 hydrochloric acid in water. ( Or use full strength and be very careful / eyes, skin etc.) Mop up. Let dry. Repeat as necessary.

I bought a house like that once. Always astounded us the stuff he’d done.

anyway, it’s just effervescence. Don’t worry, certainly don’t paint or sand them! They just need cleaning, and as someone has oddly put them inside, then maybe seal when it’s all gone.

https://wausautile.com/blog/concrete-efflorescence.cfm#:~:text=Efflorescence%20is%20a%20white%20deposit,and%20pores%20of%20the%20material.

https://www.mcmonaglestone.com/aftercare/efflorescence-a-natural-stone-nightmare/#:~:text=Efflorescence%20is%20a%20white%20substance,leaving%20behind%20the%20crystalline%20deposits.

There are also plenty of products to do the job. However I had it in Indian sandstone and just hosed and scrubbed it off, it reappeared another couple of times then gone completely.

https://www.amazon.co.uk/Everbuild-SALT1-Salt-SPRAYABLE-Clear/dp/B006FTDY8A/ref=sr_1_5?crid=33VSSA8AFXH4W&keywords=efflorescence%2Bremover&qid=1704735388&rdc=1&sprefix=Effervescent%2Bremover%2Caps%2C63&sr=8-5&th=1

As others have said its from the salts in the material. When some materials get wet the moisture brings the salts to the surface,the moisture then drys and leaves the white staining behind. Looking at that picture my guess is damp coming up from where the old fireplace was.