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 Finish cracks along wood joints

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dpgetmanPlayers Union Member

296 posts
since 7/10/12

07/17/2017 06:44:32 View dpgetman's MP3 Archive View dpgetman's Classified Ads View dpgetman's Photo Albums View dpgetman's Blog Reply with Quote

Hi folks,

I have a banjo by a one-man-shop maker with a pretty good name and rep, which I bought about 5 years ago new in person.  Last year, I noticed the beginnings of splits in the finish right along wood joints on the rim, kind of like someone drew a line along the seam with a razor.  I was a little disappointed, but figured on keeping the instrument for the foreseeable future, so didn't really sweat it.  I decided to ask the shop about repairing the finish recently, though, and the reply I got was that the banjo was out of warranty, but they would be happy to give me an estimate on repairing it.  To my mind, a finish failure due, presumably, to shifting wood under the finish seems like a manufacturing issue to me that the maker should address. 

I am curious if other folks agree with me on this and to get any guidance I can about repairing that kind of finish failure myself (I believe it was finished with nitro, which I also use to finish instruments, but I have less experience with repairing them).

Thanks,

David  

sunburst

2422 posts since 9/18/10

07/17/2017 06:57:25 View sunburst's Photo Albums Reply with Quote

Wood moves. Different humidity, different temperatures... If you carry the banjo with you to places, to festivals, take it out and play it in different places, the wood will move, and when it does the finish will either have to move with the wood or it will crack. Even a very flexible finish will often eventually crack at wood joints as a result of wood movement.
I do not think it is the fault of the maker, it is because the banjo is made of wood.

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dpgetmanPlayers Union Member

296 posts since 7/10/12

07/17/2017 07:51:11View dpgetman's MP3 Archive View dpgetman's Classified Ads View dpgetman's Photo Albums View dpgetman's Blog Reply with Quote

Thanks John,

I assumed shifting wood was the cause... Just for clarification, this banjo has never really left my house, it lives in the cabinet with 5 other banjos ranging in age from <10 to >100, all of which have their own various issues, but none of which show anything so clearly structural.  I get that instruments age, but cracks along the joints in <5 years?  

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Fathand

Canada
10101 posts since 2/7/08

07/17/2017 08:15:00View Fathand's MP3 Archive View Fathand's Photo Albums View Fathand's Blog Reply with Quote

The banjo is out of warranty, Finish is also cosmetic, similar to how a paint job on a car is less likely to be warrantied than say the transmission or in case of a banjo the neck falling off.

Read your warranty to see if any coverage still exists. You could talk to the builder who may repair it as a goodwill gesture or to maintain his good name.

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mbanza

United States
1852 posts since 9/16/07

07/17/2017 08:16:24 View mbanza's Photo Albums Reply with Quote

A similar problem I've encountered is contiued shrinkage from moisture introduced during glue-up.  Shaping and finishing too soon results in the edges of glue joints protruding as wood adjacent to them continues to shrink:  They become visible and you can feel them.

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pickin_fool

Canada
107 posts since 6/30/17

07/17/2017 11:07:01 Reply with Quote

if it is a lacquer finish you might be able to repair it with minimal effort and cost..furniture touch-up people use what they call an amalgamator to repair cracks in finish..not sayin it will work in your case but its worth a shot

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JReb

United States
148 posts since 6/4/05

07/17/2017 14:10:44 View JReb's Classified Ads View JReb's Photo Albums Reply with Quote

The rim laminates shouldn't be moving. Maybe the rim is starting to delaminate. I bought a high dollar banjo from Gruhns and discovered a spot like that. The glue clearly didn't hold in that area. I filled it with glue and crossed my fingers. BTW it's very humid in Gruhns store.

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Hedge Hog

United States
878 posts since 3/4/08

07/17/2017 14:24:55 View Hedge Hog's Photo Albums Reply with Quote

The word "move" is a relative thing.  Wood expands and contracts with humidity and heat.  I imagine that is the sort of movement they are referring to.  Real movement such as in delaminating would be unacceptable.

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rudyPlayers Union Member

United States
10862 posts since 3/27/04

07/17/2017 15:11:22View rudy's MP3 Archive View rudy's Photo Albums View rudy's Blog Reply with Quote

quote:
Originally posted by dpgetman

Hi folks,

I have a banjo by a one-man-shop maker with a pretty good name and rep, which I bought about 5 years ago new in person.  Last year, I noticed the beginnings of splits in the finish right along wood joints on the rim, kind of like someone drew a line along the seam with a razor.  I was a little disappointed, but figured on keeping the instrument for the foreseeable future, so didn't really sweat it.  I decided to ask the shop about repairing the finish recently, though, and the reply I got was that the banjo was out of warranty, but they would be happy to give me an estimate on repairing it.  To my mind, a finish failure due, presumably, to shifting wood under the finish seems like a manufacturing issue to me that the maker should address. 

I am curious if other folks agree with me on this and to get any guidance I can about repairing that kind of finish failure myself (I believe it was finished with nitro, which I also use to finish instruments, but I have less experience with repairing them).

Thanks,

David  


Maybe I missed it; are you by chance referring to vertical joints in a block constructed rim?

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beegee

United States
20033 posts since 7/6/05

07/17/2017 16:09:49View beegee's MP3 Archive View beegee's Photo Albums View beegee's Blog Reply with Quote

I have found that I can sometimes repair those little seam cracks by applying some superglue and scraping flush until the crack goes away. It takes several applications of thin glue. Once it has set up(I don't like to use accelerator because I want it to wick into the crack as much as possible), I apply enough until it is built up so I can scrape it with a razor blade with scotch tape on each end. One it is level, I can wet-sand and buff.

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John GribblePlayers Union Member

Japan
4110 posts since 5/14/07

07/17/2017 18:03:15 View John Gribble's Photo Albums Reply with Quote

Finishes continue to dry long after the instrument is assembled, especially lacquer finishes. What you percieve as cracks may simply be the finish taking on the contour of the underlying surface instead of "floating" above it.  

If the finish was thick to begin with, sometimes it can be polished flat and shiney again. But that is risky (one might polish through to bare wood) and will thin the finish even more than the drying has.  

These changes in the finish are not bad. They mean the instrument is maturing, "breaking in," and probably developing its voice. 

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G Edward Porgie

United States
3583 posts since 8/28/13

07/17/2017 18:51:26 Reply with Quote

"I believe it was finished with nitro..."

Before you try anything, I suggest you find out if that actually is what the banjo was finished with. You certainly don't want to have further issues by using the wrong stuff on it.

I would get in touch with the maker again. Be friendly and reasonable, but find out exactly what he uses. You might also ask the maker about options he might be willing to offer, such as professional touch-up. 

Personally I don't believe he's at fault in the least, and I can't blame him for not wishing to redo the banjo under warrantee (he gave it less than five years for a reason). A finish is something that takes abuse from some players (I'm not saying you are one of those abusive players) and some people also think that just any polish is appropriate. A maker certainly can't cover scratches and dings, and he is not in control of the weather. While finishes that have had good treatment may last longer than yours, excrement does happen from time to time. Most builders know this and can be really decent about making things satisfactory. If nothing else, you may get from him some very valuable knowledge on how to handle minor finish problems yourself.

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dpgetmanPlayers Union Member

296 posts since 7/10/12

07/18/2017 07:17:07View dpgetman's MP3 Archive View dpgetman's Classified Ads View dpgetman's Photo Albums View dpgetman's Blog Reply with Quote

 

Maybe I missed it; are you by chance referring to vertical joints in a block constructed rim?


Hi Rudy,

Yes, I am referring to the joints in a block rim construction.

David 

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rudyPlayers Union Member

United States
10862 posts since 3/27/04

07/18/2017 08:03:48View rudy's MP3 Archive View rudy's Photo Albums View rudy's Blog Reply with Quote

quote:
Originally posted by dpgetman

Maybe I missed it; are you by chance referring to vertical joints in a block constructed rim?


Hi Rudy,

Yes, I am referring to the joints in a block rim construction.

David 


Thanks for the clarification, David.  There's all sorts of replies here, some making obvious reference to laminated rims and others pertaining to the entire instrument.

There are pros and cons for all manners of rim construction and the finish anomalies that you have noted are part and parcel for block rims.

Any time we try to make wood conform to a shape that introduces built in stress the possibility of glue line stress failure is possible, and that's what is seen in many of the early three ply rims.  Manufacturers have a tendency to try and minimize the amount of work that goes into producing an object, sometimes deeming the long term integrity to be of much consideration.

The block rim attempts to remove built-in stress, but does so at the expense of all those visible segment joints.  The end joints are the most troublesome, as end joints are very weak to begin with.  Couple that with seasonal movement and you get finish cracks, especially with nitrocellulose finishes that don't react as well as other finishes to under finish wood movement.  Nitro isn't known for its ability to "stretch".

All that said, nothing short of a complete refinish will likely eliminate the cracks for very long.  Even a complete refinish will likely have the same eventual failure.  It's part of the "charm" of block construction.

All of us folks that engage in banjo construction eventually settle into a path that we consider best, but there's trade-offs in any direction.

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rcc56

United States
688 posts since 2/20/16

07/18/2017 11:19:46 View rcc56's Classified Ads Reply with Quote

One of the qualities of nitrocellulose lacquer is that it shrinks very slowly for many years as it gives off its solvents.  As it shrinks, it tends to check or craze, sink into the grain of the wood it is covering, and sink into seams between joints.  These are things we look for when we are trying to evaluate the age of a finish.  It is a natural part of the aging process of the lacquer.

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dpgetmanPlayers Union Member

296 posts since 7/10/12

07/18/2017 13:18:53View dpgetman's MP3 Archive View dpgetman's Classified Ads View dpgetman's Photo Albums View dpgetman's Blog Reply with Quote

Thanks folks, I appreciate all the replies.  I always learn a lot about so many things when I post here and, occasionally, even about the original topic!  I also make block rims and am motivated by the responses here to really dig into the best finish for that particular construction, if not nitro.  Perhaps SSS had it right way back when... clad the dang things in metal!

Much obliged, happy pickin!

David 

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