Sealing inside the box

No tonal change....just like there isn't if you put only one or two coats of shellac on the outside of a top.

Shellac is a very good humidity barrier (i assumed it wouldn't act as a great barrier until i saw a graph showing that it was one of the best).- (forget where i saw the graph though)
 
I do it (shellac) for three reasons: for humidity issues and stabilization, contrary to opinions I do think it may effect sonic properties although I have no evidence that it does so and this may be just bias on my part and finally, it just looks cool when you peer through the hole.

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I never seal the insides of my instruments. It makes a future repair-person's job harder and also sealing isn't so feasible for a lot of the instruments I build, such as lutes and ouds which have paper between ribs.
 
This is the graph i was talking about that shows how good shellac is as a moisture barrier
It's from the book that the Wood Database website sells.

Jo- smart to not seal lutes and ouds.
I spoke to a cello maker today and he seals the insides. His cellos are $60k each.

The aerosol spray can of Bullseye is dewaxed (as is the pint can of sanding sealer of the same brand). ALl the other ones are waxed (including the pint can that looks identical to the aerosol spray can)

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Bowed instruments are normally assembled with HHG and are meant to be regularly disassembled, so sealing the inside is not an issue as far as repairs are concerned.
 
Yes, the Bullseye liquid stuff in the can is waxed and the stuff in the aerosol can is de-waxed. By the way, I called up Zinnser and talked with them about their product. I was trying to decipher their codes as to expiration dates. It is in code and if you know how to break it it will tell you the manufacture date. This is very important with shellac as it has a limited shelf life. Wonder why they do that? Hmmmm.... ($$$???). Also I learned that it is a 3 pound cut. I dilute to 1 or 2 pounds which is contrary to the instructions on the can. Have had no problems. Perhaps the instructions are due to ($$$)???

I say don't worry about using waxed shellac for shellacking the inside of an instrument. As I understand it, waxed shellacs do not dry as hard and are softer than the de-waxed stuff. However this is not an issue on the inside... (These statements might trigger a lot of opinions which will derail the thread)... As to the point about shellacking the inside and future repairs: I am not a repair person but I definitely get how this could cause big problems. This might be why the Big Boys don't do it.
 
It would be interesting to know whether the top makers such as Martin, Taylor, Gibson, Lowden etc.etc. seal their instruments internally. I'm guessing they don't, but if anyone knows differently?
 
Zinnser used to have de-waxed available in the can but I haven't seen it for a long time. It's not that hard to mix up your own with the flakes.
 
Used sealing inside of my ukes,
with acrylic vernish for canvas painting.
But not the backside top.
Love to think that sound waves rebound on sides et back to go faster to the top ...
Don't smile.
Think also that sealant secure gluing bars.
And it's cool to see sealant by the sound hole ...
Don't smile again ...

Gerard.

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I don't shellac the inside of any of my instruments. 2 coats of tong oil (wipe on and wipe off) is great for sealing the inside. It brings out the color of the wood and works as a great vapor barrier and protectant. But most of all it dries clean.... No shellac film. I also use it on the outside of my soft wood creations (bass wood, cypress, or butter nut) to stand up the hairs prior to the final sanding.
 
Works two ways..if the moisture is already in the wood which is often the case unless you live in Death Valley then it hinders the moisture drying out.
I dont do it co's its not in the specification. :)
 
shows how good shellac is as a moisture barrier

That surprises me as I know from experience that shellac doesn't withstand water but just cracks and let's the water through.

I shellac'ed a wooden cycle fender and left it in the rain and had to redo the whole thing.
 
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This question pops up now and again, and what it amounts to is that the majority don't do it, including the big manufacturers as previously mentioned. I think that tells us it's unnecessary.
 
This thread is bumped up by spammer forsythan. Seems nobody reported him. I just reported.
Please be sure to check if an old thread is bumped by spammer before you reply.
 
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