I recently started removing carpet to reveal the stained concrete floors beneath. After taking up the carpet and the old glue, I'm cleaning the concrete, but it's now showing a chalky white residue until it gets wet. When I mop the floors, they dry back to that white chalky look just a few minutes later. We bought this house last year, so I'm not sure how long the carpet was there or what's causing this. I've read that it could be a moisture issue, but I'm unsure how to resolve it. I want to get this sorted out before staining the concrete. Any guidance would be appreciated! I'll try to share a photo showing the difference after mopping.
3 Answers
Yep, that definitely sounds like efflorescence. I suggest using EFF-Ex, it can really help deal with it effectively! It should take care of that white residue for you.
Sounds like you're dealing with efflorescence, which is pretty common when there’s moisture in the concrete. A trick to check is taping some Saran Wrap to the concrete for a day to see if any moisture builds up underneath it. If it does, that confirms the moisture problem. As for staining, check the instructions on your stain to see if it mentions moisture concerns, since that could affect how well the stain adheres.
If moisture forms under the wrap, what should I do next? I just want to ensure the concrete is good to go before proceeding!
Just a heads up, concrete’s alkaline nature means that if you’ve been using any acid-based cleaners to remove the glue, that can also cause it to turn white. Make sure what you’re using is suitable for concrete to avoid further issues.

I haven't heard of EFF-Ex before, but I'll definitely check it out for our place. Thanks for the tip!