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Blog 153: Wuyi Oolong’s “Toad’s Back”

Experienced tea drinkers would know that infused Wuyi oolong leaves often have many “bubble-like” humps. This phenomenon is more visible on heavily roasted Wuyi oolong products. Because of the look is very similar to a toad’s back, these humps are called “toad’s back/蛤蟆背”。

Some tea lovers claim that “toad’s back” is a sign of good quality oolong teas. Is this true? Today, let’s talk about why some oolong leaves have these “humps”.

The term “toad’s back” first appear in The Classic of Tea, an ancient book written by Mr. Lu Yu between 760 CE to 762 CE. In this book, Mr. Lu described “toad’s back” as an indication for reducing heating during “Zhi Cha/炙茶”, an ancient way of tea drinking.

In today’s tea-drinking, “Zhi Cha” is already history but the term “toad’s back” is still used by modern tea makers. Today, “toad’s back” refers specifically to roasted Wuyi oolong leaves’ uneven humps on the surface.

“Toad’s back” is also a term used in professional oolong tea assessment. Tea experts check “bubble-like” humps on dry and infused leaves.

As we all know, Wuyi oolong has a unique roasting process. Wuyi oolong’s roasting temperature is between 125℃/257 to 135℃/275℉. In this high-temperature environment, a leaf woud start to shrink, but parts of the leaf would expand (imagining fried foods). This is the reason why only Wuyi oolong leaves have “toad’s back”.

However, not all Wuyi oolong can develop “toad’s back”. The emergence of “toad’s back” requires a high temperature and multiple rounds of roasting. Because the high roasting temperature, leaves cannot be roasted for too long. Normally, one round of roasting is about 10-12 hours. Light to medium roast Wuyi oolong products typically have only one to two rounds of roasting. This is insufficient to develop a large amount “toad’s back”.

Heavily roasted Wuyi oolong products, such as Rou Gui and Shui Xian, have three or more rounds of roasting. As a result, heavily roasted Wuyi oolong products have more obvious “toad’s back”.

Does “toad’s back” indicate good quality?

Not necessarily. “Toad’s back” alone cannot present the overall quality of a Wuyi oolong.

There’re many types of “toad’s back”. The appearance of “toad’s back” can only tell the quality of the roasting process as well as some crucial facts, such the temperature and the balance of the roast. Furthermore, experienced tea makers can also learn more about roasting process. For example, whether leaves were flipped in time (see Blog 30 for more); if leaves were burned; or how thorough the roast was, etc.

There are three major types of “toad’s back”, and they show different roasting results.

1. If leaves are yellowish brown, soft, bright, and have a larger number of bigger humps, it indicates a thorough, high-temperature roast. Wuyi oolong tea products with this type of roast commonly have a thicker and calming tastes and aromas, and they can be stored for a long time.

2. If leaves are still yellowish brown, soft, bright, but fewer humps on leaves, and humps are significantly smaller, it means these leaves were roasted at a lower temperature. Most light and medium roast, such as Huang Guan Yin and Golden Peony, would have this type of “toad’s back”.

3. If there’re lots large humps on leaves, but leaves are dark brown and hard, it indicates leaves were roasted wrong. The typical causes of this problem are excessive temperature, sudden temperature change during the roast. Both causes might lead to the carbonization of leaves. Tea products with this type of “toad’s back” are considered “junk-grade”.

We hope you enjoyed today’s blog. As always, if you have questions or suggestions, please leave a comment, tweet us @valleybrooktea or email the author directly at Please also follow us on Instagram @valleybrooktea and join our mail list to get our daily tea updates and our latest promotions!

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