How to remove paint from concrete floor before tiling

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Removing paint from concrete floor in preparation for tile

Having never done this before, I have found I'm pretty terrible at grinding concrete. Did I remove enough of the paint for SLC or thinset to stick? If the middle of the floor is good enough, how do I get the paint off where the grinder won't reach? I slid the dust shield face over and that's as close as I could get. Is there a paint remover compound I should use to get the paint off the edges?

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Stay away from any chemical strippers. While they appear to remove the paint, the paint will be dissolved and drop deeper into the pores. It’s not what you want.

What is on the business end of that grinder?

As far as judging if the slab has been sufficiently ground:
Drip some water on there for a few minutes. If it soaks in or leaves a wet stain when you towel it off, you’ve opened up the pores sufficiently. As for the edges, forget about it unless you’re installing tiny mosaics. With any tile bigger than a few inches, the lack of a great bond on that little edge won’t matter.

Last edited by Tool Guy - Kg; 05-20-2018 at 02:21 AM. Reason: Spelling

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The business end is a double row diamond cup. The paint is over 10 years old and is quite stubborn.

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This one.

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Oh, and the tiles will be 12" squares. I will be doing Ditra before that.

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That's a nice looking slab, from-the-picture it looks like you've done a great job removing the paint. For the edges, I'd put some water on the paint and use a 4" razor scraper (Have a fresh blade on it). Sometimes the scraper alone takes the paint up but water does help things. After it's to your satisfaction, I'd get a clean bucket of water and large sponge and lightly wash the floor. It picks up all the fine dust and gives great adhesion for your tile, SLC, or crack iso after its dry.

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Justin
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what's the order

Okay, thanks everybody.

So, I've only done tile over Ditra on wood subfloor previously, so this is my first on concrete. You'll notice that there's a crack in the slab in the upper right of the pic. Some years ago when I started this, CX didn't give me much hope of a lasting tile installation, but I chose to roll the dice anyway. I haven't been able to work on this for quite some time and the crack hasn't moved in those years, but it always was raised compared to the rest of the slab. Therefore, do I pour SLC first, then Ditra, then tile - or what is the correct order?

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bump

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You'd pour SLC first, then Ditra.

However, CX's caveat about tiling over a crack where there's a difference in plane between the two sides still very much applies.

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Lou

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Yeah, that's what I thought, i.e. SLC then Ditra. Thanks.

And I'm hoping fortune is in my favor on tiling over the crack, but I'm not expecting a miracle.

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