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Thread: Washboard Back - Too Dry or Too Damp?

  1. #1

    Default Washboard Back - Too Dry or Too Damp?

    I bought a mandolin from the classifieds here. Very nice small builder mando, second or third hand. The back has some beautiful "fishbone" figure, but when I look down the back at an angle the back looks like a washboard. Every "bone" is like a "wave". I can feel it when I rub my hand up and down the back. There is no finish checking and all the joints seem tight. Slight upward bow in neck, but still plays easily. Action is a little high and the bridge is all the way down. I can't get the "waves" to show up in a photo.

    My first thought was that this was a result of drying out, but I read on the Montana Lutherie site that when you can feel the curl of a maple back it is a sign of over humidification. What do you guys think. How can I be sure, and what to do, if anything.

  2. #2
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    Default Re: Washboard Back - Too Dry or Too Damp?

    There have been discussions about this before. I used to have a tenor guitar with a back like that. Some builders chined in to say that this characteristic is indicative of hand work, probably the the back was smoothed with a hand scraper instead of being machine sanded. It is apparently common in hand built fine quality violins. So you probably shouldn’t do anything about it. It is what it is. If I were you, I’d be much more worried about the action being too high with the bridge all the way down, and the bowed neck.
    Don

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  3. #3

    Default Re: Washboard Back - Too Dry or Too Damp?

    My Gibson Bill Monroe model mandolin has the ripples as you describe. I have been told various things about why it's like this.

    One was that the maple was not cured enough before finish was applied. I think the finish used on the Monroe models was Behlens,and sprayed on. Nothing like say Nugget or Gilchrist's "varnish".
    It's more like a urethane type varnish(glossy/thick-looking) than violin-type varnish. Looks more like nitrocellulose-lacquer.

    I don't know. Have asked the same question myself.

    PS:my Monroe mando lived for years in the high desert New Mexico(built in Montana) and was hardly over-humidified. Now resides
    in a very humid locale. The ripples have not changed at all.

  4. #4
    Registered User sunburst's Avatar
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    Default Re: Washboard Back - Too Dry or Too Damp?

    Wood moves. It is normal.

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  6. #5

    Default Re: Washboard Back - Too Dry or Too Damp?

    Thanks for the responses. I found some green verdigree growing under and around the edges of the tailpiece which sounds like it was in a moist environment. It came from around Dallas where I think it's pretty humid. Don, the neck bow is slight and will be remedied when I replace the frets which are due. The action at the 12th is about .075". The bridge stands right at .75" above the top. The break angle is 16 degrees. I've got plenty of room for adjustment. However, I wanted to make sure if the top is raised from too much moisture that I don't go changing things before it has time to go back to normal. I might not need to make changes after all. I can live with the washboard. In fact, it's kind of cool, and the figure is striking.

    So, my real question is how to tell if it's wet or dry, and if it's wet is there any way to dry it other than to wait until it acclimates at its new home.

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    Default Re: Washboard Back - Too Dry or Too Damp?

    Do all types of finish shrink/thin as it cures (like varnish)

  8. #7

    Default Re: Washboard Back - Too Dry or Too Damp?

    There's not enough information here to know for sure, but I'll say that it would be very rare for a curly maple back to be perfectly flat, well flat as in a perfect curve in the case of a carved instrument. The same is true of a spruce top. The localized runout that causes the curl causes the sanding/shaping tools to cut differently, similar to the early/late wood on spruce. The finish may react slightly differently too. Under a thin finish the differences will be apparent in the right light or by feel.

    If your mandolin is in a reasonable environment - not too humid and not too dry - there's no reason to be concerned over what you've described.

  9. #8

    Default Re: Washboard Back - Too Dry or Too Damp?

    Thanks Buck. I'll wait a couple of weeks, checking measurements, and see if there is any change. The mando is eleven years old and should be stable except for moisture changes. That will give me time to wake it back up.

  10. #9
    Adrian Minarovic
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    Default Re: Washboard Back - Too Dry or Too Damp?

    Quote Originally Posted by tbrahan View Post
    Thanks Buck. I'll wait a couple of weeks, checking measurements, and see if there is any change. The mando is eleven years old and should be stable except for moisture changes. That will give me time to wake it back up.
    When John said wood moves he meant it goes both ways. There's no final state of dryness. When environment is mor ehumid the wood expands, when it is dryer it will shrink and since wood shrinks/expands differently in various directions the changing grain wll necessarily show through no matter what method was used to smooth it out before finish. The more severe the curl is the more pronounced ripple you'll get. Of course it the instrument was built at different (higher or lower) humidity than it is normally stored it can show up sooner...
    Here is some extreme example of old fiddle (N.Amati I believe). You don't have to touch it...
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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    Adrian

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  12. #10

    Default Re: Washboard Back - Too Dry or Too Damp?

    Just saw Sunburst's post. John, you are the "Master Po" of tonewoods. If I could just snatch the pebble........

    Adrian, that is exactly what I am seeing. I appreciate your comments. Wood is in a constant state of change. I probably knew that, but this looked, incorrectly, to me to be an extreme case. Now that I know it is not, I will stop worrying. Still I will let it get used to my place before making any adjustments.

  13. #11

    Default Re: Washboard Back - Too Dry or Too Damp?

    It is interesting that of the dozen or so mandolins I have owned,only one demonstrates these ripples. I think it's a cool look;no problems with it.
    My Monroe does have,as Adrian described,a fairly "severe" curl to the maple.Click image for larger version. 

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    Harder than I thought to show the ripples.

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