rockm

"Why unsealed, Rockm?

Also, I didn't have shoots sprout from around the cut. The cut areas have been pretty barren"

Cedar elm usually sprouts thickly from cut sites and from pruning. That's what makes them good material. There could be other things going on For instance, are you cutting back the top or other areas of the tree at the same time you're hoping to have the wound heal? Is there any growth near the cut site at all--above below, within four inches? If there is let it alone and let it grow. Also, healing can be accelerated if you just let the tree alone unpruned for the growing season. This takes some patience, but it usually works.

Also, I'd avoid stark soil like akadama for this species. Cedar elm loves water and moist soil that doesn't dry out. It lives in areas near rivers, in low lying areas too. Fast draining soil may not provide it with either the constant moisture it requires (not soggy, but moist) nor the nutrients it needs. Fast draining soil leaches out fertlizer pretty quickly.

These are only suggestions as to what might be going on. A cedar elm that doesn't push new growth or buds at hard purning sites, nor heal wounds is an exception in my experience with them.

"4 years sounds like a long time to me."

Depends on the wound size and what you think is a "long" time. A large chop wounds--over an inch or two--take a number of years to close on most trees. BC take three or four years to close large trunk chops (sometimes more, depending on the size of the trunk that was removed) korean and carolina hornbeam can take a decade or longer to close the same sized wound in a container.

I would also note that you don't want a wound to necessarily close quickly. A fast healing wound that closes in a year usually is accompanied by thick rolling scar tissue that ruins the chop work. Chops on some species, like beech, are done in late fall or early winter and not spring for this reason.