How to remove yellow stain on honed concrete flooring?

[AM1234]

Hi guys, i have a yellow stain on my terrazzo or honed concrete flooring. I have tried CLR (Calcium, Lime, Rust remover 1L - link below) from Bunnings but it doesn't seem to have worked.

https://www.bunnings.com.au/clr-1l-calcium-lime-rust-remover_p4460670?srsltid=AfmBOoqEp2E-O1S2OYD0S4...

The previous owners left the stain and i'm not too sure what its caused by. Has anyone had this before and know what product to use to get rid of it? 

Thank you 

[JacobZ]

Hi @AM1234,

Welcome to the Bunnings Workshop community, it is fantastic to have you with us.

I could only take a guess at what's caused it, but it looks to be a pretty uniform shape, so I suspect something was sitting on it for a considerable amount of time and has leached something which has seeped into the concrete or affected to the sealer.

You've already tried CLR, which would be my usual starting point, so next I would try a concrete cleaner such as this Chemtech Concrete And Driveway Cleaner, testing it in a small area before committing to the wider application.

Mix it with warm water following the recommended ratio on the packaging, then apply it to the concrete and give it a good scrub with something like this Oates Long Handle Deck Scrub Brush.

If this has no effect, then I suspect the staining has gone deeper into the concrete and the best option would be to grind it off, repolish and reseal the surface. If this is the case, I woud suggest contacting a concrete grinding and polishing company for their assistance.

Allow me to tag @Dave-1, @Nailbag and @AlanM52 to see what they think.

Let me know if you have any further questions.

Jacob

[Dave-1]

Good morning @AM1234 

Ugg, and my go to products would be the same as yours. 

There are heaps of network outlets on teh walls, makes me think that maybe there was a rubber mat of some kind sitting on the floor. @JacobZ concrete cleaner would be my next step. 

If that dosnt work I would be thinking if somethingrought to really scrub the floor (mechanised) but not cutting it. I am hopping it is leftover rubber backed stain. So a scourer pad to really scrub it hard.

Dave

[Nailbag]

Hi @AM1234 

Unfortunately I can't offer anything new. I would also go with @JacobZ suggestions with a regrind and polish as your last resort.

Nailbag

[AlanM52]

Hi @AM1234,

@Dave-1's thoughts about leaching are correct.

Chemical leaching between dissimilar materials is quite commonplace - almost inevitable.

Can you hang on while I go take some photos.

OK... I'm back.

Bottom of the stairs.

Original family home built in 1971, continuous traffic all the living is upstairs and never any floor covering at the bottom.

We moved back in 2004 and since then started using mats because the dogs were skidding into the wall doing zoomies up and down the stairs.

A bit obscured with daylight coming in through the entry foyer windows.

After dark with stairwell light on quite obvious.

Bathroom with your regular bath mats.

Morning sun although diffused by the bathroom window also plays a part here.

Shower mat area is very obvious!

Cheers

[AM1234]

@AlanM52 

Thanks, how did you end up removing the mat stains? 

[AlanM52]

@AM1234,

The stains are still there and we put up with it because they are only seen when the cleaning lady is doing her rounds.

Having said that this discussion has given me the incentive to see what can be done to remove the stains.

Google search 'how to remove rubber mat stains from linoleum' returns this AI result:

To remove rubber mat stains from linoleum, start by cleaning the area with a solution of warm water and mild dish soap. For stubborn stains, try a paste of baking soda and water, or use a commercial vinyl floor cleaner and a soft brush. Rubbing alcohol or a magic eraser can also be effective, but test in an inconspicuous area first to ensure they don't damage the linoleum.

Assuming some sort of rubber backing:

To remove rubber mat stains from honed concrete flooring, start by trying a gentle approach with a mild soap solution and a soft brush. If the stain persists, consider a stronger cleaning solution like a concrete cleaner or a diluted acid solution (like muriatic acid, used cautiously). Always test any cleaning solution in an inconspicuous area first and rinse thoroughly. 

Cheers