Can anyone who knows anything about wood floors please help asap

[IHopeYouStepOnALegPiece]

Cleaning water marks off the floor yesterday, gave it a last once over last night and this morning this had appeared.

Didn’t use too much water as cleaning water marks so didn’t want to make worse and no cleaning fluid was there.

It’s not dirt and isn’t coming off with scrubbing.

PLEASE help!

Thank you

I'm not sure but it looks like the marks were made by wiping/mopping.

Was there something on the cloth/mop that has seeped in and stained it?

The tannic acid in the wood is water soluble and can react with alkalis, could there have been something alkaline on the cloth/mop?

Maybe call the manufacturer for advice?