How do I ensure a level, seamless capstone on a retaining wall?

[Baitball Blogger]

The wall was made out of rough, Rumblestone, but it's as level as this type of paver allows. The capstone is Travertine. It was an obvious great buy, probably the last of a large order and we just lucked into it because the buyer wanted to move inventory. It takes 5 of the Travertine capstones to cover the top of a 120 inch wall. A couple of the Travertine tiles move a bit, but if we gently life one side of the stone, it all fits seamlessly.

We were going to use Loctite PL 500, but I have a hunch we are going to have to use cement. Maybe Heat Stop, because it will be four feet from a firepit?

https://www.amazon.com/Mutual-Industries-60090700-0-0-Heat-Stop/dp/B00XNQL6GK/ref=as_li_ss_tl?ie=UTF8&qid=1466781800&sr=8-6-spell&keywords=heatstop+mortar&linkCode=sl1&tag=shiyouligblo-20&linkId=5f53c14ef7a1443decc3c68e134377e6

Am I on the right track?

[randr]

1. Use a thin set mortar mix

Place it thick enough under caps so they self level with some tapping. Clean out any that oozes out before it sets. Not sure why you would worry about the heat as stone will take a lot and you have 4 feet which should be adequate. If you can stand 4 feet away surely the wall can

[Baitball Blogger]

2. Thank you for responding.

We'll use the thin set mortar mix, as you suggest. Makes sense. I only mentioned the heating cement out of ignorance. I read a DIY article, and she was adhering capstone to an actual fire pit. In her case, it was necessary. But I wasn't sure of the rules of distance. We obviously don't need it. Thank you again.

[randr]

3. Share a pic when you finish

[Baitball Blogger]

4. I'll PM you the photo.

We're almost finished. We just need a few rain days to help clean up the stone so we can be sure we have the ones with the best marbling. We washed them down, but they're still dusty.