old fiddle repair jobbie

[matthew]

This old fiddle was given to me in a parlous state. Tonight I removed the top.

The front has a crack that runs almost the whole length and the lower bout ribs are cracked at the block.



The bass bar is not original, this top probably has an integral bar when first built.



The linings appear to be feathered to nothing at the corners and blocks glued in over the top. The linings are therefore neatly tucked behind the blocks.



Underneath the thick black buildup of rosin the wood looks nice.







The inside has some odd hurried-looking gouge marks at the eyes of the FFs.



The crack in the rib is clean and won't be too much trouble, I hope.



The only mark inside is a barely legible pencil scribble near the neck that looks like "60YO", a sure sign of a master instrument. Yeah, right.



There is no neck block. The neck runs right through and glued into the plates directly.

[kiwigeo]

"SOYO"......A Japanese Whaling Company that unsuccesfully tried to branch out into violin making.

Looks like a nice challenging repair job there Matthew. Progress pics of same would be much appreciated.

Cheers Martin

[matthew]

I've been spending some careful time with the gunk on this fiddle.

It seems the rosin and dirt is actually fused with the spirit varnish. I've been as gentle as I can but its frustrating. On the one hand it seems like I should preserve the original varnish at all costs. On the other hand, this is a fiddle of unknown quality. Although the varnish was once very nice, now it is pretty ugly and dirty. So I could just strip the finish on the belly and revarnish to show off the grain and purfling.

However that's a big undertaking too, so I'm persevering with gentler methods.



The black buildup adds a certain character to the thing, but obscures the grain of the wood. The purfling is all but invisible in places.



in places it is so thick that the line of the FFs is obscured



I resorted to scraping gently under the loupe but this takes the finish off to a matte layer, and its too easy to break through the last layer to the yellow wood underneath. Not really satisfactory.





Best result I have had so far is simply 320 grit abrasive paper on my forefinger. I can control the rubbing and grind the rosin buildup down to the level of the varnish, more or less. It is not going to preserve all the the original finish, but it blends the rubbed rosin with the existing varnish. So I think I'm going to have to french polish this top, and try to blend in some new lac with the old and any residue of rosin left.

[Paul B]

What about chemicals?

I don't know what rosin is like chemically, but I'm wondering if there's a solvent that will dissolve the rosin and not the varnish. Shellite (Naptha) maybe? Hexane?

That's a pretty cool project Mathew. Wish I could find me a gunky little fiddle.

Welcome back BTW.

[matthew]

yeah the problem with chemicals is that they always seem to dissolve the varnish too.
you can use meths or acetone or xylene or toluene etc but they all damage the shellac underneath. In any case, the rosin seems actually fused with the shellac, so there is no dividing line.

Right now I'm cleaning up the cracks with meths and a stiff brush and some dilute oxalic acid. Rosin and grime in the cracks means I can't glue it. Once its clean I'll glue it up and THEN go back to work on the finish.

[sebastiaan56]

Hi Mathew,

That seems like a staggering amount of rosin. Its hard to imagine a pro allowing that to happen to their instrument. Do you know its history? It certainly looks like a challenge to me.

Sebastiaan

[matthew]

I don't think a pro owned it!

I think it was a folk fiddle, well loved, played a lot, but not well cared for. Probably got left in a car often, which caused the rosin to bake on and the cracks to form.

[Paul B]

Neither shellite or hexane should damage the varnish. Hexane is sold in the automotive industry as grease and wax remover, the stuff you wipe a finish down with prior to spraying on a new coat. At least it smells the same as hexane.

I'll have a look in the chemical bibles when I'm back in the lab tomorrow, see what rosin is soluble in. There's got to be an easier way than chipping it off.

[James Mc]

Ok this is going to sound incredibly harsh. If you’re not going to be able to save the varnish (looking at the photos it doesn’t look like you will) then try paint stripper. Do a small area at a time let it wet through for 10 min or so give it a quick scrape then scrub it with steel wool and metho. I wouldn’t recommend this for laminated timbers but I’ve used this method on solid timbers with no problems.

[kiwigeo]

Rosin is basically resin is it not? Resin is mixed with shellac by some so one would assume then that the resin like the shellac is soluble in alcohol??

I believe the problem with leaving rosin on a varnish is that after a while the rosin acutally bonds with the varnish. Not surprising as varnish usually contains resins.

Heres one discussion on the topic which may help:
http://www.thesession.org/discussions/display/3840

[Paul B]

Yeah, forget about it.

Varnish sometimes contains rosin, so the chemical path isn't going to work without great risk. I've been reading up....

Mechanical scraping is probably the only way.

Still a pretty cool little project. I bet that thing is gonna sound great. Someone obviously played the hell out of it for a long time. That doesn't tend to happen with a shitty sounding instrument.

[matthew]

yes both rosin and shellac are soluble in alcohol. The varnish is shellac-based so unless I can find a solvent that is very selective its mechanical means only. And I think the Rosin HAS bonded with the shellac over time. So it may all have to come off. In which case I'll be using alcohol, not stripper.

[kittykatjaz]

Wow Matt, you really have your work cut out there!!

Please keep us posted with your progress,

Jaz