I use a 12" diameter by 18" long piece of maple that had been cut
for about 6 months. Left the bark on for “aesthetics”. I smoothed
off the top and cut several depressions and groves in it. I also
sunk a hole to take the posts of a stake. After a year and a half
there are several cracks. All large pieces of wood will crack! There
is no way to prevent it in a stump size block. The good thing is
that this piece is very portable for demos. I place it on a wood
stool and flail away. The public loves it. I always have enough
copper scrap on hand for the adventurous to try something too. Fold
forming gives some quick, simple hands on pieces. Great PR.
Anyway, your stump will crack! Nothing you can do to stop that other
soaking it for a few years in Polyethylene Glycol. Waxing or
painting only slows down the process. Just work where the cracks
aren’t. I would remove the bark on the Elm, Walnut, Gum, and some
Oaks. The Maples and Poplars are OK left on. It is not as much a bug
problem as it is the bark crumbling when it is dried out.
Sorry that you lost a special tree. The “stump” could become a
family story piece! Hope so.