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Thread: Sealing inside the box

  1. #1
    Join Date
    Jul 2019
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    ..........
    Last edited by Dougbias; 10-02-2019 at 12:17 PM.

  2. #2
    Join Date
    May 2018
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    Kekaha, Kauai
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    The changes in tone are insignificant and it may slow down the changes caused by humidity, but won’t prevent them. I do not do it because it makes repair work on the inside, like adding cleats for crack repair, a nightmare.
    Bradford Donaldson
    Kekaha, HI and Cannon Beach OR
    bradfordj48@outlook.com

  3. #3
    Join Date
    Dec 2011
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    Grand Junction, Colorado
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    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)

  4. #4
    Join Date
    Oct 2014
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    Little River, California
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    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.

    sealedbox.jpg

  5. #5
    Join Date
    Oct 2014
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    Little River, California
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    Quote Originally Posted by Dougbias View Post
    is the Zinnser Bullseye Home Depot stuff good enough?
    Good enough...

  6. #6
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    May 2010
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    London, UK
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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.
    My Website
    The stringed instrument database which I also run.
    I play far too many instruments to list, but I like 4 courses of nylon strings best!

  7. #7
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    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)

    68968306_519572092148959_5367740205442793472_n.jpg
    67763401_363145784355417_2080494858400694272_n.jpg

  8. #8
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    May 2018
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    Kekaha, Kauai
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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.
    Bradford Donaldson
    Kekaha, HI and Cannon Beach OR
    bradfordj48@outlook.com

  9. #9
    Join Date
    Oct 2014
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    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.

  10. #10
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    Sep 2015
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    Stockport, Cheshire.
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    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?

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