More I've studied on it, more I've come to realize waxiness is the key to good sealers. All the the latex paints and elastomeric roof sealers and the like breathe too much. Far better than nothing, but not nearly what Anchor Seal or Klingspor's Green Wood Sealer equivalent or blended mineral oil/beeswax will achieve. Not bothered much by cracking as beautiful epoxy fills of cracks are part of my stock in trade as a woodworker, they always just look better the more subtle and narrow that they are. A big pie slice crack full of epoxy doesn't look particularly good. On the flip side, end grain rarely looks that all great, so some artistic enhancement of it often helps. Best end grain cookie table I ever did was this from a hollowed out guanacaste cookie in Mexico with a custom cut blue glass inlay. But after I sold it, the wood kept shrinking in an air conditioned office and exploded the glass.I'd like to know if your successful with the Ash cookies. In January, I dropped a very large, 30" plus diameter ash that EAB killed. Cut several cookies, at different times. 1st cracked within a week and continues to do so. The next several, through some very helpful members here suggested coating both sides. I used a water based ceramic roof coating. Cracked, but not as severe or as soon. Cut a 2 1/2 center hole in one, coated, so far so good. Last one I cut into a pie shape; 4 slices coated. As I cross cutting, it started to split, mildly, but hasn't advanced. Checks about 14% moisture content. Keeping fingers crossed. The above mentioned pieces are for a 9-year-old to paint, so appearance if reglued isn't an issue.
I did try cutting a slab. without a mill. Beautiful grain, but not very even.
Good luck!