Power washer?

Does the tile still have a shiny finish or glaze underneath the paint? How many square feet do you have?

Hi, thanks for the comments. I doubt that a power washer will work, but I think it's still worth a try! No shiny glaze underneath the paint. It is around 30 square meters so 322 square feet.

Thanks Jan, appreciated.

IMO you either paint it now or remove it. How do you know it was chalk paint that stuff usually does not stick like that. You will now have to remove any bit of the stuff you have tried before you can paint it too,

Thanks for info. I agree that paint is not going to come off gracefully because the original shiny glaze is gone. Test for lead before sanding or scraping. Then decide what color you want to paint over.

I doubt chalk paint is containing any lead: )

If the original poster didn't apply the paint and know what was in the can, it's better to test than assume it's lead free paint. Various areas implemented lead paint standards at different dates.

Apply paint stripper and cover with plastic so it doesn't evaporate so quickly. See if this has any effect. If it does, you could then use a floor buffer with either a wire brush or a pad driver and black/coarse stripping pad. Make sure any fumes are vented before buffing.

what room is this in? If it's a super casual room, I'd just cover it with carpet. if it's a laundry or craft room, utility carpet or cheap carpet squares. or like others said, paint over it now, and you can put down a big area rug to hide most of it.

if you really must remove the paint: given that you've already tried all the standard things, it's probably going to be easier to sand with a power sander. I agree with apple_pie_order. test the paint and the glaze for lead first. or just rip it all out and re-tile.

On second thought, the more I look at your pictures, the more I think that this was a glazed tile and the glaze is chipping off in places. If so, nothing short of sanding would remove the color.

How do you know it's chalk paint?

If it is glaze there's a greater chance it contains lead.

Can you just remove it? Rent a jackhammer and take it out! Then lay something you like. Or primer it and paint

actually scratch my former comment. I can see this is a patio or sunroom. just paint over it like others suggested, and lay down a big indoor/outdoor rug.

or consider covering it up with teak patio tiles: