I have been cutting osage recently and only removing the bark and sealing over the sapwood and ends with titebond 3. I can tell you that alot of pieces haven't checked at all along the sapwood, and most won't check on the main portion of the back, or of the peices that I have got recently. Takes 3 or 4 layers of tb3 on the ends and at least 2 on the back to seal good. But if they start checking on the end, it will go down the back and into the sapwood. It's always more likely to check at a knot, and always of course at the ends. But I totally believe everyones advice to remove sapwood soon. Almost everybody on here probably has more experience than me with osage. I haven't had any of these staves over 3 or 4 months anyway so who knows what il happen, they might all get ruined if I don't get the sapwood off soon enough. The sapwood does check super fast if you don't get something on it either the day or next day you cut it. I mean 2 days and it will be checked into the heartwood, so waiting till the next day is as long as you can wait really. I like to wait till the next day for a little bit of moisture to leave the back, but not enough to start checking. It's just usually soakin wet right after the bark is removed. The checks start as black lines on the sapwood I have realized (with the stuff I got anyway, may be different for you), and if I let them go with out sealing em they spread, get longer and darker and then start to turn into cracks. The lines usually start at the ends, and rarely in the middle.