Violin Forum/Message Board

[Dave Chandler]

In my previous violins, I waited untill it was fully assembled before sealing the wood. On my last project, I assembled the back and ribs, used the assembled ribs to create an outline my top, then sealed the back and ribs with 1#cut shellac while working on the top. When it finally came time to assemble, the back/ribs shape had changed, now my overhang is uneven.

My thinking was that because the shellac was cut with alcohol, it wouldn't swell the wood like a water base sealer, but apparently it does. It may be because it took me a week or two to get the top ready. Meanwhile, I rescraped the back several times to removed raised grain, and then sealed it again. Maybe its because the interior was unsealed while the exterior was sealed, and uneven humidity may have caused some reshaping. Any thoughts? Work faster (ha)?

This violin has a real pretty quilted maple back and ribs, and that in itself creates a number of optical issues making it difficult to tell if you are looking at indentations and unusual bends, or just optical reflections. Even holding it at different angles fools the eye.
_________________
Dave in the Blue Ridge
Southern Violin Association

"Success is the ability to go from one failure to the next with no loss of enthusiasm" Winston Churchill

"I took the road less travelled, and now I don't know where I am." Marco Polo

[Jack H.]

normally the ribs are kept in the form until it is glued to the back to prevent any distortions.
i would seal the instrument in its entirety and not in pieces.
Might get some shelack on the gluing surface of the ribs...

[Dave Chandler]

Thanks Jack, think I'll go back to my old way. Easy enough to remove sealer from blocks, quick swipe on the sanding board. Curious about gluing the back to the ribs while still on the mold, presume that you don't add the linings for the top until you've removed the mold. Seems it would add some potential for distortion of the ribs adding linings off the mold. What's your secret? Collapsible mold?
_________________
Dave in the Blue Ridge
Southern Violin Association

"Success is the ability to go from one failure to the next with no loss of enthusiasm" Winston Churchill

"I took the road less travelled, and now I don't know where I am." Marco Polo

[jethro]

Dave:
On my first violin I let the completed body hang from a nail on my pegboard for about 6 months. the humidity here can be 60-110% most
of the time. Over that time the body was slowly unbending- on its way to
going back to a round hoop ! I too a piece of 3/4 hardwood plywood about 12 x 20 and lais the body down on it. Then I cut a slew of little
triangles about 2 inches on a side and glued them all down to the ply
on the outside of the body holding inward on it. I have one about every
inch all round. Then there are a couple of balsa sticks in the center to
keep presure pushing the ribs outward against the many little blocks.
It has worked great for shape control. You just take the sticks out and
lift it straight up and out when you want it out. How does thaat sound ?

Tim

[Dave Chandler]

Jethro,
Sounds like a pretty good system (and something like an outside form), the blocks all around and wood strips pushing outward. You have a lot of humidity, I'm running about 45-55% almost all the time.

Back to sealing the back and top seperately -- I'm thinking it was not a good idea in hindsight. It seems the lag time between gluing the back to the ribs and getting the top on is critical, so on my current project, no sealing, no purfling, no fooling around during this period. Otherwise, although the variations are minor, if the purfling is already done on the top, you're pretty much stuck with the variations in the overhang if there are any.

What about sealing the interior -- Alcohol base or water base sealer for the interior? I've read about a early 20th cent maker that used a concoction that included hot water, egg white, something else I can't remember now. If you did, it would seem it would be at the last moment before gluing the top on. Anyone have experience with this?
_________________
Dave in the Blue Ridge
Southern Violin Association

"Success is the ability to go from one failure to the next with no loss of enthusiasm" Winston Churchill

"I took the road less travelled, and now I don't know where I am." Marco Polo

[violinarius]

Take a piece of excess rib material, and coat one side with shellac, and then observe.

[Jack H.]

[Dave Chandler]

Jack,

You're probably right, there has to be some shellac that seeps deep into the end pores of the blocks that just removing the obvious sheen doesn't address, but I was pretty careful not to seal any gluing surfaces.

I would think that even though the alcohol in the shellac evaporates off pretty fast, any swelling at all and the dried shellac in the pores would prevent its returning to its original shape, and so even the slightest swelling would be permanent.

I'm with you, wait till its all complete before sealing.

I like using a 1# cut clear shellac because it dries very quickly, and almost immediately, and because of the slight sheen you can detect and address issues before moving on to the varnishing. It also stiffens the grain so that another quick tour with the scraper results in an even smoother surface. What do most makers use for a wood sealer?
_________________
Dave in the Blue Ridge
Southern Violin Association

"Success is the ability to go from one failure to the next with no loss of enthusiasm" Winston Churchill

"I took the road less travelled, and now I don't know where I am." Marco Polo