Just don't expect the bark to stay on forever. It's frustrating but bark just won't stay on a dead tree forever, if you are regularly handling it, no matter how well you seal it or try to protect it.

Eighteen dollars for a slab of firewood? Man, I am in the WRONG business.

It's a slab of firewood planed and sanded with at least $2-3 in mineral oil rubbed into it! Then again, firewood is like $4.50 a bundle now so maybe it's not that far off anymore.

ash trees will be extinct in a few years if the ash borer isn't stopped (an invasive pest from asia that has no known predators in north america that has killed millions of trees throughout the midwest) so you can also consider the slab that was rubbed with oil and sanded by a human to be a fossil of sorts.