I know I'm not the only one here who does DIY tile installation.

I laid some Monday - finished late evening.

Went back Wed thinking I could replace some drywall & grout, but the adhesive was still soft = tiles could slide around.

Put a fan on it & turned AC on to remove moisture.

Went back this AM & still not completely dry. Better, but crackling when pressed on.

I've not installed such thick tile before, only 1 x 1" in sheets & 3 x 6 subway. These are much thicker, 1' hexagons - floor.

I used the appropriate 1/4" notched trowel. Acrylpro adhesive with 48-72 hr drying time.

Starting to wonder if there is a problem, or am I just impatient?

DJ, a few ideas...

1) How old was the mortar? Is it something you've had sitting around for a long time? Might have a shelf life. If you bought new, does it have a date on the container?

2) Do you have any adhesive left? If so, put some on a piece of wood as a test piece...do it in 3 different thicknesses, with one of them being very thin like the thickness of a dime...and watch how it dries hour by hour at home.

3) What was the substrate? If it's very porous, could pull most of the moisture out of the mortar and affect the chemical reaction.

4) What type of tile? Ceramic? Porcelain? Other? For non-porous tiles like porcelain you need a polymer modified thinset.

Thank you all for pointing me in the right direction.

I'll post my error here, so maybe someone can learn from MY mistake, and not have to make it themselves.

It's on a concrete slab. Don't remember the type of tile(I didn't buy it - doing this for a friend) but this adhesive says it's good for all of them - it says so in the FINE PRINT on the container. It also says it's recommended for small tiles & "dry time will be extended if using larger tiles". Don't know how long it will be extended, but it sounds like it will - eventually - dry & be OK.

Lesson: If you don't choose it, SEE the tile ahead of time, find out what it's made of, and read the fine print. Even if you have to zoom in for a photo then zoom in on the photo to read it, like I did.

From what little I just looked up on that adhesive I think you are just being impatient.

Anything over 8x8 has an extended cure time. You said you are using one foot hex tiles. Also I would think that being on concrete will add to the cure time as it doesn't absorb as much into the substrate.

Enjoy the house guest for a bit and wait it out.

Also remember that no good deed goes unpunished. Free jobs have a tendency to come back on you somehow. At least it always seems that way for me.

Robert are you talking about Ditra membrane?