I wasn't sure which forum to post this on, but will try here first.

We finally moved in to our ICF home a few months back. Just 2 weeks ago, we made a decision on the fireplace (finally!) and it was tiled with honed vein cut travertine. As you can see from the pictures, it's very tall (20' ceilings) and at the top there are still a lot of "spots" remaining on the tile.

Initially, the ENTIRE fireplace looked like this upon application. (The tiles did not look like this new in the box). However, after grouting everything, the "spotty" look disappeared and it turned out great, except for about 2 feet at the very top. We keep wondering if it could be moisture at the top and it's just not getting as much air circulation to dry, but as time goes on and there are no changes, that does not appear to be a correct theory. It has been over 2 weeks now.

Any advice on what these marks are, and what the cause could be? Thanks in advance for any and all comments re: this.

p.s. It doesn't seem to want to allow me to post more than one picture, so I will hopefully be able to do so in a reply post.