We just grouted our bathroom wall tiles (smoooth white subway style pattern) with smooth white pre mixed grout. It isn't going in well and is now cracking and hardneing with bums and edges :( Do we have to do another coat or will that be too thick... it is showing some thinset and the edges of the tile too

We never recommend using anything that comes pre-mixed for ceramic tile especially for wet areas. Lots of horror stories from non suspecting DIY's. Sometimes these products never dry. And most shrink and crack.

The thinset is showing because you didn't clean it when you installed the tiles. Applying another coat may work? Or remove it and use real grout?

Jaz

Jazman

Thanks you that's what I figured. Now next question can I use sanded grout (not premixed) over the current smooth premix as a top coat to cover these problems

We never recommend using anything that comes pre-mixed for ceramic tile especially for wet areas. Lots of horror stories from non suspecting DIY's. Sometimes these products never dry. And most shrink and crack.

The thinset is showing because you didn't clean it when you installed the tiles. Applying another coat may work? Or remove it and use real grout?

Jaz

We would rather not remove it (lots of work) but rather cover it. Can we now use a sanded grout to do the last coat?

With those tiles I would figure your joints are narrow, probably around 1/16"? You need un-sanded up to 1/8"width. New grout is not going to stick to the grout already there. Grout needs to also "grab" to the sides of the tiles. You should have about the top 3/16" or so open for grout.

Although it'll be a PITA, it shouldn't be that hard to remove that stuff.

Jaz

I agree with Jazman. At this point you can't make a silk purse out of a sows ear. Your thinset was not properly clean between the tiles, probably way too thick also. Your premix was not pushed into the grout line far enough so it cracked and now you'd like sanded to grout to hide the whole mess, it won't work. You need to undo any much,many of your mistakes and the regrout the proper way.