Black vs. sweet gum
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Q: I need to know what the difference is between black gum compared to sweet gum, and how do I identify black gum. I think I am getting black gum in my sweet gum and our customers do not want it.

A: Sweetgum (Latin name Liquidambar styraciflua ) has white to light pink sapwood (sometimes sold as sap gum) and reddish brown to brown heartwood (sometimes sold as red gum).

Black gum (sometimes called tupelo gum) (Latin name Nyssa sylvatica ) has sapwood that is light gray brown and heartwood that is darker gray brown.

Positive separation of the wood (if the color does not provide obvious separation) can only be done with a microscope. Even with x10 magnification, they cannot be separated with certainty. I am curious what keys your customers are using to indicate they have black gum, as the experts cannot usually separate the two!

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About the author
Gene Wengert

Gene Wengert (1942-2025) was popularly known as “The Wood Doctor.” He trained thousands of people in efficient use of wood for more than 50 years and authored foundational resources on wood technology. He worked at the University of Wisconsin-Madison and Virginia Tech. His popular "Wood Doctor's Rx" column has appeared regularly in FDM and FDMC magazine since 1978. Because so much of his advice was timeless, he asked that we continue to run his columns in memoriam.