You can buy pre-mixed thinset pals and you will not have to worry about it!

Add about 3/4 of the expected water to the bucket. Add the thinset. Mix. Slowly add a bit of water and continue mixing until you get a good consistency. It is impossible to to take water out once you've added it, so just add a bit at a time and continue mixing.

Also, Don't try to make big batches. If you can't use it in under an hour, you made too much. Slow and steady wins the DIY tiling race.

I made it up in small batches which made my life so much easier. Put in the water, then the thinset until I think its right. I use a plastic spoon to the hold test and then let sit for five minutes, mix again. These 12x12 tiles take a lot of mortar and I try to get a lot on the cbu which starts to starts sagging down. I use the 1/4x1/4x1/4 towel to make the ridges but I'm not doing something right. Because when I check the tile less then 50% of it is covered with mortar so I have to butter it.

Most people have better luck with a 3/8" trowel for 12x12. Make sure you are pulling at a 45 degree angle too. A shallow angle will pull off too much thinset and you won't get good coverage.

Also, I suggest you try the mixing method I posted earlier instead of trying to add dry mix to a soupy bucket. It is a whole lot easier to add "a little" water than "a little" dry thinset when you are getting close to the consistency you want.

Wish I had gotten your post earlier, just came back from HD. Oh well, they are getting use to seeing me everyday anyway. I don't think I was doing the 45 degree angle because I was pulling off quite a bit of thinset.
So instead of using the dry mortar to get the right consistency use water instead. As long as it doesn't kill my drill, I'll try it. But that seems to be opposite of what the bag shows.

Pulling the thinset off the CBU can also mean that you're not "burning it in" to the surface of the CBU, so to speak.

First, make sure the CBU isn't dusty. Wipe it down with a sponge until it wipes down clean.

CBUs, especially hardie, can wick water out of the thinset, "drying" it out prematurely. Misting your CBU with a spray bottle, letting it soak in, and then tiling can help.

Apply the thinset to the CBU with the flat side of the trowel. Really work it in to the surface for a few seconds, Work it so you get the thinset in to the textured surface of the CBU. Spread it around so you leave a little over 1/8th inch thickness. The >1/8" thickness isn't not crucial, just a technique.

Then come back and comb it out with the notched side of the trowel. Combing from bottom-to-top may help too.

If they need buttering, use the same technique on the back side of the tiles, but only with the flat edge of the trowel. Again, you want to work the thinset in to any texture on the back of the tile, then remove most of the thinset with the flat edge of the trowel. Like lightly buttered toast.

For nice flat tiles, you don't really want a thick opaque thickness on the back of the tiles. You want a well-worked in "smear".

If your tiles are not flat, or if they have a textured back side; a waffle pattern or other mold markings, you might need more thinset than a smear.

Just like the CBU, some tiles might have dust on the back too. Any powdery residue might inhibit the thinset from sticking to the tile. Theoretically you could have enough thinset on the CBU, but when you test set a tile then pull off the tile to check thinset coverage, not much is sticking to the tile due to the dust. The dust is acting like a release agent.

Lots of variables. But you're developing a new skill set, and the next project will be easier.

Remember a lot of tiling is "technique". What works for me or bill may not work for you. Eventually you find your way, things come together, and it all seems so easy.

The tile I'm using has the waffle so yea I put it on thick then spread it smooth. Then I push that baby on to the cbu which cause some to ooze out. I use a putty knife and rag to get between the side before it had a chance to dry. Its looks like a lot of thinset to me (thickness between the cbu and tile is about 1/4) but the tiles I put up there are somewhat even and flat. I wipe the board down before I start but it takes me so long between tile that I try to remember to wipe again. I did have spray bottle yesterday but forgot to use it.
I got the 1/4in x 3/8in trowel so hopefully this will help using it at a the 45 degree angle.

I screwed up the kerdi band on my niche so now I have to see if I can fix this new problem. Thank you guys for your help, I really do appreciate it.

Mongoct,

Mixing the mortar the way you suggested worked. However, I wished I had posted sooner. The mortar stuck the tile out a little from the other tile so its going to take some work to get this right.

Mongo, you do a terrific job of explaining things. I am always so happy to read your solutions to our problems!

Mori, glad to read things are coming along.

Enduring, thanks. Maybe it's a byproduct of homeschooling my kids years ago, lol. Did you ever get around to tiling the 6x12 herringbone?

What do you do when you mix mortar with too much water and don't have enough mortar to make it thicker ?

You need another bag of the same product NOW! Dig a hole in your yard and pour it out.

Agreed!!

You mentioned Kerdi...so this is a Kerdi shower? What brand and type of thinset are you using?

@ harry_wild "...So my question is what am I doing wrong?"

Not using any measuring devices for the thin-set or the water. A digital food scale is the best thing you can have when mixing small units of thin-set or grout. You can see an example of the scale in action here: MIXING GROUT IN SMALL BATCHES The link shows Permacolour grout but the principles can be used for any product. I find that most manufactures have the water ratio a little dry. I like to use the upper end of their specification and for installing sheet membranes and uncoupling membranes often increase the water ration a good 5-15% beyond the printed spec.

@ Derrick M - "What do you do when you mix mortar with too much water and don't have enough mortar to make it thicker ?"

You are kind of hooped it this happens. Not much you can do. The thin-set is too wet so it will not have the proper strength at all. Like what Tundra says - DUMP IT.

If the thin-set is just a hair over watered you might leave it an hour to kick off a bit. Sometimes I mix my mix and let it sit for a good half hour to hour before using it. When I want it a little thicker but want the mix to be the same as all the rest.