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Thread: Reinforcing Bowl of Bowlback mandolin?

  1. #1
    Registered User bobskiebudgie's Avatar
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    Question Reinforcing Bowl of Bowlback mandolin?

    I was wondering if there was any way to reinforce the bowl of a bowlback mandolin. I have an old italian mandolin and I would like to reinforce the bowl.

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    Default Re: Reinforcing Bowl of Bowlback mandolin?

    Is it of any value? Do you want it as a player? Or wall hanger? Can you show photos?

    The above are important questions because a player may be repaired differently than a wall hanger. depending on the problem they it may be easy or quite a complex problem.

    We need more information.
    Bart McNeil

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    Registered User Tavy's Avatar
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    Default Re: Reinforcing Bowl of Bowlback mandolin?

    More information is definitely required: why do you want to reinforce the bowl? Normally these are repaired by pushing open joins back together and re-gluing, then possibly adding some cleats to the inside. Inspite of the inherent flimsyness of these bowls, reinforcement isn't normally required.

    HTH, John.

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    Registered User bobskiebudgie's Avatar
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    Default Re: Reinforcing Bowl of Bowlback mandolin?

    Thanks for the answer Tavy. The reason I wanted to reinforce the back was just for a bit of added strength but it should be fine!
    By the way, what are cleats?

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    Registered User Tavy's Avatar
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    Default Re: Reinforcing Bowl of Bowlback mandolin?

    Quote Originally Posted by bobskiebudgie View Post
    Thanks for the answer Tavy. The reason I wanted to reinforce the back was just for a bit of added strength but it should be fine!
    By the way, what are cleats?
    Reinforcements to cracks, here's a cello top with rather a lot taken from here:

    Click image for larger version. 

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  6. #6

    Default Re: Reinforcing Bowl of Bowlback mandolin?

    Quote Originally Posted by Tavy View Post
    Reinforcements to cracks, here's a cello top with rather a lot taken from here:

    Click image for larger version. 

Name:	cellorepair-13.jpg 
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ID:	81706
    uhhhhhh....

    wow.

  7. #7
    Registered User Tavy's Avatar
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    Default Re: Reinforcing Bowl of Bowlback mandolin?

    Quote Originally Posted by labraid View Post
    uhhhhhh....

    wow.
    LOL, that's what I thought when I saw those pictures too!!

  8. #8

    Default Re: Reinforcing Bowl of Bowlback mandolin?

    I wonder why more repair folk don't do the spruce shaving as opposed to the cleat. Any idea Tavy?

  9. #9
    Registered User bobskiebudgie's Avatar
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    Default Re: Reinforcing Bowl of Bowlback mandolin?

    I think I may have figured out how to do this. Could I stick lots of cloth inside and that would reinforce it?
    bobskie

  10. #10

    Default Re: Reinforcing Bowl of Bowlback mandolin?

    Quote Originally Posted by bobskiebudgie View Post
    I think I may have figured out how to do this. Could I stick lots of cloth inside and that would reinforce it?
    The term "reinforce" is so loose.. As is stuffing lots of cloth inside something.

  11. #11
    Moderator MikeEdgerton's Avatar
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    Default Re: Reinforcing Bowl of Bowlback mandolin?

    That cello top is similar to John Fahey's Recording King Guitar.

    This is probably a silly question but how much does a bowlback back vibrate? Does the back add significantly to the sound that is being projected through vibration?

  12. #12

    Default Re: Reinforcing Bowl of Bowlback mandolin?

    Quote Originally Posted by MikeEdgerton View Post
    That cello top is similar to John Fahey's Recording King Guitar.

    This is probably a silly question but how much does a bowlback back vibrate? Does the back add significantly to the sound that is being projected through vibration?
    I don't feel the back vibrate a lot when I play one, and yet those with heavy bowls sound quite different from those with eggshell-like bowls...

  13. #13
    I may be old but I'm ugly billhay4's Avatar
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    Default Re: Reinforcing Bowl of Bowlback mandolin?

    bobskie,
    You're not helping the very experienced and talented people here who could really help you. They need a precise description of what is wrong (if anything) with this instrument that makes you want to reinforce the bowl. Pictures would really help. Terms like "stick lots of cloth inside" really violate the spirit of instrument making, aside from being so vague that no one really knows what you have in mind.
    You CAN reinforce a bowl with cloth. That, and Brian's spruce shavings, are how it is traditionally done. But this is not a "bunch" of cloth, but a thin layer glued inside the bowl. How will you get in there? What kind of cloth will you use? Glue?
    Let these people help you. You might have an instrument that deserves it.
    Bill

  14. #14
    Moderator MikeEdgerton's Avatar
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    Default Re: Reinforcing Bowl of Bowlback mandolin?

    I've never really understood the physics of the bowlback.

  15. #15

    Default Re: Reinforcing Bowl of Bowlback mandolin?

    Yeah but they just look too cool for school.
    Kip...
    Blessings,
    Kip...

    If you think you can or think you can't... you're likely right!

    Eastman MD515, amid many guitars and a dulcimer.

  16. #16

    Default Re: Reinforcing Bowl of Bowlback mandolin?

    The goal of the system in classical mandolin is to create a highly reactive top, richened by a light, airy bowl, which should in fact resonate and "flow" with the strings' energy. In heavier bowls, the bowl isolates itself from the top, simply acts as a container for air volume, and is in many ways like a capacitor -- reflecting back whatever energy is put in. The tone is thinner, more acute and piercing, less musical -- only one small surface is producing the bulk of the sound. In lighter bowls, you get a sense of richness: the whole of the instrument is working together, creating a smoother, more lush tone. Of course the top needs to be crafted to match... There must be interplay.

  17. #17
    Moderator MikeEdgerton's Avatar
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    Default Re: Reinforcing Bowl of Bowlback mandolin?

    Thanks for the explanation. I've always wondered about this. I know that the more expensive models produced by major manufacturers generally had more ribs, did that in any way equate to a lighter bowl?

  18. #18

    Default Re: Reinforcing Bowl of Bowlback mandolin?

    I think the number of ribs is more for that precision look, an Audi/Porsche sort of thing.. And it commands a bit more respect, as well as a higher price, partly because of the work involved. Each rib takes about a half hour to fit, then there's the scalloping. It's really about the prestige I'd say, and rightfully so.. A good classical is a mighty force. Might as well look the part.

  19. #19
    Moderator MikeEdgerton's Avatar
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    Default Re: Reinforcing Bowl of Bowlback mandolin?

    I always figured that the expense was in the workmanship but like I said, I never really understood what was happening in the bowlback. Thanks for the information.

  20. #20
    Registered User Bill Snyder's Avatar
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    Default Re: Reinforcing Bowl of Bowlback mandolin?

    Brian's scope of work and knowledge is a wonderful set to add to all the other fine builders that are a part of the Mandolin Cafe.
    Bill Snyder

  21. #21

    Default Re: Reinforcing Bowl of Bowlback mandolin?

    My first mandolin was a bowlback, built by Heinrick Moritz Schuster in Markneukirchen, Germany. It was a wall hanger in an antique store, but I wanted to learn to play so I repaired the cracks, etc. As I recall, the inside of the bowl was made or perhaps previously repaired with newspaper strips, shellaced to the inside of the staves of the bowl. I didn't want to take the top off to repair the crack on the bowl, so I worked yellow glue into the crack and clamped it together. After that, I poured a little two-part epoxy resin into the bowl and tilted and swirled it around to coat the inside, creating a sort of thin epoxy shell inside to reinforce the bowl. I never had another problem with cracking, but I don't know if it hurt tone or not, since I never heard the mandolin prior to the repair. For what it is worth, I thought it sounded good...loud with a bright attack. Not the gentle tones of an F style, but bowlbacks never do sound like that.

  22. #22

    Default Re: Reinforcing Bowl of Bowlback mandolin?

    Quote Originally Posted by eastmountain View Post
    For what it is worth, I thought it sounded good...loud with a bright attack. Not the gentle tones of an F style, but bowlbacks never do sound like that.
    The modern German bowlback most certainly has a soft, gentle tone, much akin to the classical guitar -- they go superbly well together in fact. It excels as a solo instrument precisely because it lacks the harshness traditionally associated with Italian bowlbacks. The Italian bowlback excels at piercing through a large orchestra, with a tone to differentiate itself markedly from the other instruments. This is the benefit to that bright piercing tone. Here is an example of the softer, modern German sound:


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