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Kiln dried rounds splitting
(lemmy.world)
Advice needed. I sanded the tops of these kiln dried rounds and then coated both sides with shellac. Most of them split a few days later.
The untouched rounds have been stable.
How can I make these smooth and shiny and keep them intact?
I find it interesting that the untouched rounds are (so far!) doing better. I don't have any answers, but I'll speculate.
Shellac is pretty permeable to water vapour. I don't know how much it slows the exchange of water vapour, but it might not be much.
I would be curious how sanding alone affects stability. I can imagine sanding increasing the surface area exposed to the atmosphere, speeding up the exchange of water vapour.
I'm going to experiment a bit.
While you're at it, maybe plane or scrape a couple of rounds, too. If sanding marks and raised grain really do increase the exposed area, getting rid of them will reduce it.
I would think someone out there has already done the experiments, but I didn't find anything with a quick look.
Also, if you're not committed to shellac, there are coatings that are less permeable to water vapour.