Understanding the end grain
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Centered growth rings indicate
the post is made from
peeler core and won't accept
pressure treatment well
(right), while off-center rings
mean the post is not the
log's center (left).
4x4s are typically made from “peeler
cores,” which are the byproduct of plywood
production. When a log is turned
on a lathe to produce plywood veneer,
the center that remains, called the peeler core, is used as a post. These cores often
contain the pith, or center of the log,
which doesn't accept pressure treatment
as well. Peeler-core posts are more likely
to warp and twist than posts cut farther
away from a tree's center.
When shopping for 4x4 posts, look at
the ends. If growth rings start near the
center of the post and expand outward,
it's almost certainly made from a peeler
core. If the rings are off
center, it's not the log's center. Buy 10-ft.
posts instead of peeler-core 8-footers and
trim them to fit.