Well, I know Neil’s Tama kit had all the shells coated with fiberglass resin. I would imagine it would brighten the sound and raise the pitch a bit.

But, I think recutting the bearing edges would be better money spent, as long as the person/shop doing it knows what they’re doing.

The shellac will help in projection of sound...The luan is very porous, so, sealing it with shellac will help prevent the wood from absorbing the sound...

Cheers

I’ve used a few coats tung oil to luan shells with success. It’s a longer process but worth it. Natural and also helps waterproof it. You can google tung oil for info.

As far as sound, not sure I can detect a difference with my ears.

I wouldn’t expect much change with tung oil. It is extremely thin and closely follows the pores in the wood.

I would recommend Polyurethane if you are looking to brighten the sound. It's much harder than shelac.

The bearing edges were recut a few years ago, totally worth it, but the guy had to do it by hand as the wood was too soft for a router. About coating the inside, if the change in sound is so subtle, I won't waste time doing this. Will probably remove the top emperor and replace with ambassador, because right now, it sound dead as hell...

Haymans had the white "vibrasonic" coating which was no more than a white polyurethane.

I think Poly would make them louder and more lively but how much, I couldn't say. A layer of woven fiberglass with a thin layer of resin applied neatly to the inside would probably make them sound really lively. I believe the wood in the Pearl Wood/Fiberglass shells was luaan but they used a chopped fiberglass mat instead of woven fabric.

Odd he couldn't cut the edges via router. I used (still have) an old DeWalt variable speed router and different species do require different speeds and feeds for best results. Also the direction of the cut can matter as well.

I had a lot of trouble with figured sugar maple. The "tiger stripes" would pull out if the cut was too deep or the blades were not just a bit sharper than razors.

I laquer the interiors of cheap woods like poplar and basswood with polyeurathane all the time. It makes an enormous difference, much more than recutting bearing edges alone (which I also do). I tried it on Luan shells once, frankly did not like the effect. Yes it made them project more and brigher, but that destroyed that natrual dark warm tone that luan is known for. It is a weird wood, can sound great or can sound terrible depending on a number of factors. If you are looking to brighten the tone, they I guess it would do what you want, but in my opinion it would be a shame. Whatever you do, stay away from tung oil on luan. It's taken the shells decades to dry out and increase resonance. Tung oil will destroy that effect. Great on maple, terrible on luan.