Re: Identifying bowlback mandolin and question about black inside
John, I don't have any photos of that old Washburn, but just checking now in Keef's "Washburn" book, in my edition on page 112 there's a tightly cropped view of the cross bracing and he makes note of it as well on page 113 in his 3.3 "General Appointments".
Not sure if you have the book, but he writes for the 1887-1896 models: "....Ribs are usually cross-braced on the inside with an oval wood centerpiece on which the Washburn logo...."
He continues for the 1896-1905 models: "....The cross bracing method (1889) is abandoned in favor of the traditional paper gluing of the inside ribs..."
I can get a photo up of but the original isn't very big or very clear either...but it does show what was inside mine.
I'm an architect, not a structural engineer, but I have built some thin shell masonry roofs of different sizes. My guess is that a bowlback bowl does behave in some manners as a shell structure and in some ways as a series of connected bent arches spanning from tailblock to neckblock. These types of constructions don't always perform in a singular manner but often as hybrids.
The thin shell masonry vaults / shells I've built definitely benefited from a skim coating of mortar on the interior. Of course they were independent tiles, not spanning ribs so how relevant they are to this discussion is up for grabs.
I suppose if it were as John described, this paper lining was tautly applied and "shrink wrapped" pulling the staves laterally into compression with each other it might add some strength to the assembly. But I've often seen the linings applied like a bad wallpaper job, which puts that into question. It might have worked as intended on some and not on others.
Somewhere, not sure if it was in print or watching online, I recall seeing bowlback ribs being assembled and the narrator / captions clearly spoke of a paper liner place on the mold as a type of "slip sheet" such as Mike describes. Or as far as my Italian language skills go it did.
Whether or not that was the same paper that wound up lining the finished bowl was not clear to me.
One or the other? Seems likely both could have been in play. The idea of a liner serving as a reinforcement must have come to someone's mind at some point. Bowlback ribs were probably splitting apart not long after the were made, for a century or more before my Washburn.
John D'A's cross rib strips seem to be clearly intended to do so.
Don't know if I've contributed anything here, but, man I enjoy these wonky deep dives into bowlback construction.
My partner is a structural engineer who is all over thin shell and tensile structures. I'll bring a bowlback into work and leave it with him and get his take. I know he'll dig it.
Thanks for getting this discussion going!
Mick
Ever tried, ever failed? No matter. Try again, fail again. Fail better.--Samuel Beckett
______________________
'05 Cuisinart Toaster
'93 Chuck Taylor lowtops
'12 Stetson Open Road
'06 Bialetti expresso maker
'14 Irish Linen Ramon Puig
Bookmarks