**Yes—very hot, especially boiling, water can contribute to cracking a natural-gourd or wooden mate cup.** A mate-cup seller specifically warns about pouring hot water into dry wood; usual brewing water is around **70–80°C (158–176°F)**. [Luv Mate’s care guide](https://www.luvmate.shop/blogs/news/ultimate-guide-how-to-cure-wood-or-gourd-mate-cup), [Taragüi’s brewing instructions](https://www.taragui.com/en/post/how-to-prepare-a-good-mate).

But heat cannot explain the first cup leaking during your **cold-water soak**. That suggests an existing crack, a thin or damaged area, or another defect. The other two could have failed because of excessive heat, pre-existing damage, or stresses as the material absorbed water; the timing alone doesn’t establish which.

Your day-long soak wasn’t an obviously unreasonable mistake: leaving yerba and water in the cup for about 24 hours is a conventional curing method, although instructions generally specify hot water. **Wooden cups can require different preparation**, so use instructions specific to the wood and maker. [Taragüi’s curing guide](https://www.taragui.com/en/post/how-to-cure-and-clean-mate).

For replacements:

- Use warm water for initial wetting and avoid boiling water.
- For calabash, scrape out softened loose pulp gently, without gouging the shell.
- Empty after use and let dry with good airflow.

If you used water around 70–80°C, I would suspect the cups’ condition or quality before concluding that you caused all three failures. Curing won’t reliably repair a through-crack that leaks.