I'm going to step outside the box here for a minute.
Sealing the ends of a log has never worked for me. The seasoning checks always got me and made my efforts result in little more than nicely dried firewood.
The term "bowl blank" apparently means different things to different people. My sources of influence conveyed the bowl blank definition as a roughly turned and sealed bowl that is either drying or dried, ready for turning.
Here's old photos of how I produce "bowl blanks"
Rough logs ready for processing
Band Saw litter from processing the round slugs
Waste that has to be dealt with
Processing the rough slugs into roughly shaped bowls, usually with a 1" or more wall thickness. Unturned slugs can be seen at the top left of this photo. Lots of damp shavings.
These are what I've always known as "bowl blanks". Green colored Anchorseal has been wiped on the end grain areas with free areas at the side grain. This way, the bowl blank dries more evenly and most importantly, more slowly. End grain sheds its water very quickly and the long grain slowly. The resulting structural end grain collapse is called a seasoning check. These bowl blanks will dry from nine months to a year.
Getting green wood in log form is a 'right now' kind of thing. The wood needs to be sawn out, rough turned, sealed, and set aside to dry. A few days of dawdling at any point of this process runs a very high risk of checking failures. That's a lot of effort to turn into firewood.
When I first got acquainted with AAW and woodturning in 1993, I've read and probably tried all the "quick and easy" ways to process green wood into turning stock. Most methods failed. The only consistent method of getting good bowls for me is the above. Sure, there are a lot of turners that process green wood into a finished product, but they use wood movement as part of the process and finishing methods have to agree with water soaked wood pores.