The boxes are coming from BeeThinking. Here is what they say from their own website.
Western Red Cedar
All of our top bar hives and Warre hives are made
from Western Red Cedar harvested in the Pacific Northwest in the United
States. While it costs more, we select only kiln dried, tight knot
Western Red Cedar for our hives. Our wood is kiln dried to between 12%
and 18% moisture to minimize warping and cracking. Other hive builders
use pine due to its availability and low cost. Pine, however, requires
painting in order to have a comparable longevity to Western Red Cedar.
We usually don’t paint our hives, but either leave them unfinished to
weather naturally, or seal them with Tung Oil.
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