Prepping finished concrete for tile?

Cup wheel and a grinder hooked to a vacuume.

If you can't identify exactly what the finish is then I'd remove it. If you know exactly what it is then call your favorite adhesive vendor and ask them. I know that's not a direct answer but that's how I'd handle it.

EthanB said:

If you can't identify exactly what the finish is then I'd remove it. If you know exactly what it is then call your favorite adhesive vendor and ask them. I know that's not a direct answer but that's how I'd handle it.

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It's that basement and garage paint with the flecks in it. Not sure what it's called.

I think Ethan has the best idea..... but I always thought the concrete should be stripped (not chemically.... ground off with a cup wheel).

If there is a different solution,,,, I've sure wasted some time in the past.... oh well.....

Mechanically stripped unless one knows, without fail 100%, the chemical reaction with the adhesive or mortar will be positive. Since it's almost impossible to know that mechanical is the safe route to take. Cup wheel on a grinder, buffer and hard plate, scarifier, shot blaster, etc. Depends on access of job site and availably of equipment.

If the epoxy is soundly adhered and is giving no signs of failing, I'd probably scarify it, put some primer or bonding agent on it, and fire away. If your adhesive is going to be thinset, I'd scarify more. If you were using a urethane to adhere an underlayment, I might do nothing more than rough sand - Bostik's Best and the like are never going to separate from it. It depends on the application and the budget.

Can we get rid of the term "cup wheel" I keep envisioning the carborundum Gigantor wheels used in the 70's .
Today they are diamond grinding blades , a multitude of different types , if you are serious about your profession you need this system . Floor prep is priority one, if it is high it needs grinding, low it needs fill, no way around it. If there is a bond breaker it should be removed.

MIKE ANTONETTI said:

Can we get rid of the term "cup wheel".

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No. Every flooring, GC, concrete, guy I know - knows what that means. Kinda like skilsaw or sawsall. You wanna spend your free time re-educating everyone so they can then be confused, be my guest lol.

p.s. The rest of your post I agree with 100%. Now where'd I put that cup wheel......

Dam, I knew you were going to reply , those grinding stones were such a pita. All of them, I still have a couple , bunch I threw away, obsolete.

MIKE ANTONETTI said:

Dam, I knew you were going to reply , those grinding stones were such a pita. All of them, I still have a couple , bunch I threw away, obsolete.

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Lol. Yeah I hate those things. They make more of a mess than actually accomplish anything.

They're still a cup wheel, just with diamond impregnated stones. A diamond blade is a flat blade you use the edge to cut tile and masonry with.

I just call them grinding blades , they're not categorized on the market very well as far as description , grit, bond, patterns , quality of diamonds, although I have a bunch and their hard to wear them out.