Acoustic Guitar Construction

I read somewhere (I don't remember where) that the braces, end, and neck (inside the box) are treated with shellac prior to closing.
I have two factory made, and one luthier made classicals none of which seem to have been treated with shellac.

Any thoughts?

Welcome!

The thought, although incorrect -- is that "sealing" will help protect the instrument from the effects of humidity change. Alvarez Yari's are the only high volume guitars I can recall that have/had finished interiors. Looks pretty cool but that is about it. You certainly want to take care about getting sealer on any surface that is going to be glued -- sealer prevents the adhesive from working properly at the molecular level -- not good!