To get heat marks off travertine, follow these steps:

1. Clean the affected area with a pH-neutral cleaner and a soft cloth to remove any dirt or debris.

2. Mix equal parts baking soda and water to create a paste.

3. Apply the paste to the heat mark, covering it completely.

4. Cover the paste with plastic wrap and let it sit overnight.

5. Remove the plastic wrap and wipe away the paste with a damp cloth.

6. If the heat mark is still visible, repeat steps 3-5 until it is gone.

7. Rinse the area with clean water and dry with a soft cloth.

Note: Avoid using acidic or abrasive cleaners on travertine as it can damage the surface.