Been years since I studied such things in school and with
Shellac it would seem now a days, there ain't crushed up bugs involved with the former........
So no given lots of Sellac available for her new dresser, what's the difference between it and Polyurathane in end result?
Yep Ship,
Shellac is still made from the carapace of the Lac Beetle.
No bugs, no Beautiful finishes. After the bugs are euthanized < Humainly, I'm sure.> they are covered in Denature alcohol and the
shellac is leeched from there little beetle bodies. Check out this place
Shellac.net It's hard to believe these guys are as excited about
shellac as they are, but they are. < maybe too many
denatured alcohol fumes....>
Major difference between Poly and
shellac is
thickness of finish, resistance to nicking/scratching Water resistance, finish times, finishing process.
Shellac can be as thick as you want it, provided you put on enough coats. Poly is going to go on thicker and require fewer coats.
Shellac is more likely to crack, on it's own, when it ages though not as much as a
varnish.
Poly's are designed to not crack.
Shellac is highly water resistant provided you are using a "common"
shellac not a "de-waxed" but long term exposure to water can lead to premature discoloration.
Poly is a man made product that inherently Hydrophiliac when setting up and impervious to water when cured.
High quality Poly's need hours to set up and days to cure, cheaper Poly's hours and hours.
Shellacs are absorbed into the wood, usually resulting in a natural staining process. Shellacs can be used on top of any finish and stick to almost anything. Poly's are usually used as a top coat over another staining product but shouldn't be used over certain oil-based stains and won't adhere to most plastics.
And most important
Polyurethane should never be eaten.
Shellac < all natural> is an FDA approved food coating.