Apologies for posting a question then disappearing. I have this job thing and some houseguests. . .
Lots of good ideas here, thanks all.
Using a full wrap of tape instead of just a piece ("duh" -- hits forehead).
Paul, good to hear from you. I ordered a set of those Milwaukee markers, there were only $5 or so for 4. I'm a little skeptical, but even if they won't write on wax they'll be useful for other things, as my current Sharpie army is on the back side of life.
I'm anxious to try embedding a piece of paper in the wax. Wondering if I can just hit a spot with a heat gun and tack the paper into the wax. I could overcoat with wax, but then I'd have to pull out the wax pan (an old single serving electric skillet to which I add old candles).
With apologies for getting on a soapbox, sealant debates almost always miss the real point. Success can be had with most any blank sealant (including latex paint and other MacGyver sealants), it's a matter of matching the sealant (and thickness of said sealant) to the wood, size/shape of the blank, and the drying environment (RH, amount of air circulation). Easy drying woods in smaller thicknesses at 60% RH can go unsealed. Earlier this summer I rough turned some holly boxes from green blanks when the shop RH was running about 55%, and I dried them unsealed without checks despite the incredibly high shrinkage rates of holly. Walls were about 3/4" (holly distorts so much you have to leave it thick) and I was willing to risk being aggressive in drying them because I wanted to avoid staining. I threw an old sheet over them to slow air circulation a little.
Thicker blanks (say 3") of even easy drying woods at the same RH will probably require end sealing. At low RH (my shop runs 25% RH in the dead of winter), even easy drying woods need some sealant on all sides to slow things down (or no sealant and double bagging in grocery bags).
Dense tropical woods generally have slower internal migration of moisture and have very high rigidity, so they have to be sealed better to make sure the outer part of the blank doesn't get too far ahead of the swollen interior. Unless you have RH tightly controlled, woods like katalox, bocote, bloodwood, chechen, etc basically need to be completely sealed in paraffin wax to slow drying enough that they won't check. The alternative is to hold them at elevated RH (like 80%) as the free water is lost, then back them down slowly. Some of you are aware that I turn a lot of spheres. A 3" sphere of those woods equilibrated to 50% RH will check if moved to 25% RH instantaneously (been there, done that). Fortunately, heartwood of those species is very rot resistant, so you can leave them sealed in wax for years and they won't degrade -- just let them dry low and slow. Seal a 6x6x3 block of maple that way and you'll have all kinds of discoloration in just a few weeks, unless the temps are low.
PVA glue, or PVA-based sealers absolutely allow faster drying than anchorseal (wax-based) or straight paraffin wax (at the same thickness), simply because dried PVA transmits moisture more readily. Whether this is a good thing or a bad thing depends on the circumstances -- the species, thickness, RH, and degree of air circulation. A maple bowl roughout that's only 1" thick would probably dry fine (and fairly quickly) under PVA, at least if the RH is not super low (<30%). If the RH is really low, you can put that PVA-coated blank in a paper bag and it will likely be fine. But I can assure you a wet 6x6x3 bocote blank sealed with PVA will check badly. PVA is too moisture permeable and bocote too drying rate sensitive for that to work.
It's not about "good" sealants or "bad" sealants. To twist a phrase, there are no bad sealants, only good sealants used badly.
So how do you know what will work? Information on general factors to consider is available, but there's usually user-specific calibration required. "Good judgement comes from experience; experience comes from bad judgment." Drying cracks are not random punishment that rains down inexplicably. Except for extremely tortured wood like crotches (or pith cracks), virtually every drying crack could have been prevented with a better alignment of the factors that affect drying. When you experience a drying crack (and we all do), think carefully about the circumstances, make a mental note of what likely went wrong, and don't repeat your mistake. You can buy electronic hygrometers (relative humidity meters) really cheap (<$5) on Amazon or your vendor of choice, and I've found them to be surprisingly accurate. Get some and put them in your shop and wherever you dry wood, and learn the annual humidity cycles in those spaces.
Soapbox off. Thanks for all the input and suggestions. Hope everyone has a great long weekend.
Dave