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I'm working with a very nice and white Italian spruce top. The grain lines at the centre are so tight (close together) that I can barely see them at all.

I use fish glue for gluing my joints and shoot the joint with 240 grit sandpaper on a level.

I join the pieces by Spanish tourniquet.

I've never seen this before but I do have to say that most of my guitars have been cedar or redwood topped. Only have built 2 spruce guitars and this is #13.



I've inspected the joint under magnification. It's not open at all and I'm confident in the stability of the joint. Just a bit unhappy that the glue line is so dark.

Thoughts? I'm sure most will say it's the jointing method but there are many builders out there who use a sandpaper type "plane" to joint their boards as I do.




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In the close-up photo, it looks like there is a visible layer of glue between the plate halves. This should not be. Maybe it just appears that way, always hard to tell from a photo.

Grant

Have you sanded it yet?

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Yes it's sanded to thickness. I could pull it apart and reshoot it but I'm not sure I'd get any better results then I'd also have to ensure I get the plates joined perfectly flat too...

When marking the soundhole center point I can certainly feel the hard line of the glue as it is of course harder than the spruce.

The joint didn't break when testing the off cut, just the wood broke.

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Hi Rod,
A couple of important tips next go around.

1) Don't sand to thickness before installing rosette. Also, don't sand to thickness until a couple days after installing rosette to allow for complete drying of the glue - unless using CA glue.

2) Don't ever use fish glue around spruce -- it can discolor spruce exactly the way it has in your photo. I've never had this problem with any other glue but it once happened when installing soundboard binding. At spots along the end-grain, the fish glue soaked in and discolored the soundboard. I had to rip off the binding and redo. Without question, this is the result of using fish glue rather than a poor center joint.

3) The best glue for center joints is hide glue. As a general rule, use hide glue for everything you possibly can. If not hide glue, then use Titebond. Those two glues work every time for every application. I only use fish glue for attaching the plates to the sides where I want a bit of extra open time. It is a phenomenal glue but in most situations, hot hide glue or titebond will be more user-friendly.

I hope you still have a bit of material left to sand some more off that top. If so, I would cut open the seam and get rid of about 1/8" material or as much as you can possibly spare. That will get rid of the discoloration. Otherwise, I wouldn't use that top -- it will look very bad under a finish.

I have used fish glue for many years and this is about what I have discovered as well.

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Gwaltney Guitars

Thanks guys.

I have room to open this up both in thickness and in width (I've not installed the rosette yet) so I will open it up and reglue with titebond as I'm not set up with HHG.....but maybe I should?

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Hey Rod, nothing wrong with Titebond for this application.

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Gwaltney Guitars

I have always use Original Titebond -- that's five decades

I am interested in the comment about Fish Glue staining the spruces -- I have yet to use it, same experience for others?

Thank you

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Ken Cierp

http://www.kennethmichaelguitars.com/

I use it for everything but the center joint and bindings, and have never had staining. You would think I would get staining from gluing in the rosette if it is a problem, but i puddle it in and slap in the rosette with never a problem. The only reason I haven't used it on tops is I get my tops joined and rough thicknessed from LMI. I do that because a good luthier advised it on expensive top wood in that LMI discovers any problems like pitch pockets rather than myself. It is pretty cheap as I buy all my wood using the LMI kit wizard process and joining and sanding is heavily discounted at that time.
Mike

Thanks again guys for all the help. I've got the top pulled apart and in the process of joining again. As I don't have a lot of room to play with the thickness I decided to use the tape and tent method and join in my go-bar deck on a very flat stack of MDF.




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I was thinking it looked like some sort of discoloration from the glue. Sorry this happened, Rod, but it's good to find that my instincts are improving with experience. :-)

I suspect the clamping method and glue you're using for the fix will work out fine.

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George :-)

When using a level or anything straight with abrasive paper on it to do the joints it's possible for the discoloration to be the result of the debris from the abrasive paper. Especially when the same leveling/flat beam was used to sand the back halves the paper contamination gets into the joint of a lighter colored top and shows.

Another reason to shoot joints with an uber sharp plane.

We repair a lot of cracks and step one of fixing any top crack, back and sides too, is to wash our hands before poking around the joint with dirty fingers. Cracks are dirt magnets, glue it up that way and the dirt is forever enshrined in our glue.

Sorry this happened Rod.

I've never used fish glue but have read quite a bit about people using it on these fora. This is the first time I have heard any mention of it discoloring spruce. Sure enough 2 people here, plus the OP, have seen it. Have I just missed this tidbit? This seems like it should be talked about more; we talk about it all the time with CA. . .

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Bryan Bear PMoMC

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Interesting. I've been using fish glue for the past 10 guitars for purling and binding, and not a bit of staining. Even on end grain.

Steve

Rod: The set up and difficulties associated with HHG are highly exaggerated. The main problem is doing your clamping in a timely manner. Now is the time..................JUMP.......!!!
Tom

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I've seen it as well, but only when I re-hydrated it and applied heat and clamping pressure to squeeze out binding gaps. The thin and hot glue wicked up into the endgrain. Before squeezing the gaps there were no stains. I usually use hide glue for bindings and squeeze gaps the same way with no troubles. Never tried fish for center seams.

I'm sorry that it happened to you, but you seem to have solved the problem, that's great!
I had my first unlucky experience with fish glue too: I glued the rosette purflings with FG and it stained the spruce around it.
Hopefully I didn't have done the final thickness sanding and the sanding removed it in the end.
It seems that HHG and Titebond are really our best friends for all purposes..

Thanks for all the help and thoughts on the issue. I think Hesh may have nailed this issue as of course there is no end grain being glued in my scenario. But we'll see.
I put a new piece of paper on my level before shooting the second time and for the final pass I cleaned the paper with one of those large rubber "erasers".
I've not pulled it out of the deck yet to see how it turned out but I'll be sure to post a picture later tonight.


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We see this commonly on individually built Luthier guitars, the dark center seam, and it's usually a contaminated joint from abrasives. What you just did should do the trick nicely.

Just a quick wipe with a clean cloth removing debris and dust is a good idea too then tie that sucker up and put it on the rack.... Nice to see someone using and describing it as such too, a Spanish tourniquet. Some of the old ways are still very good ways and another one is the very concept of a go-bar deck. I've read that archeologists found examples of this clamping method in caves where humans 1,000 years ago were likely making their next double neck to rock out with....

Well I think this is much better.




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"We have to constantly remind ourselves what we're doing....No Luthier is putting a man on the moon!" Harry Fleishman

"Generosity is always different in the eye of the person who didn't receive anything, but who wanted some." Waddy Thomson

+1
Personally I plane to joint, but know others have success with this method.

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

I'm glad it worked out! I hated the idea of losing that top.


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Saved Rod!!!

I've probably used fish glue on the last 15 or 20. I only use it on top bracing and gluing the top to the rims. I like it because it would appear to dry harder than Titebond, similar in hide in the brittle feel in clean up. Also has a nice long open time and good tack.

I don't like the fact that it leaves a yellow stain on Spruce and doesn't clean well with a damp cloth unlike Titebond. Not really an issue on a spot where you need a mirror to see.

And like Titebond it comes in a handy, ready to use bottle.

Those are all the same reasons I like Fish glue Danny! Guess I'll just have to leave it for the same purposes as you...

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