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Fixing a Giannini classical


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Hi everyone, I've been lurking on this site for quite a while now and it's time I finally emerged from the shadows. I've just picked up an Ebay gamble, in the form of a 1970s Giannini classical guitar which has a heel crack, but the draw on this old girl is a Brazilian rosewood body and mahogany neck. The heel crack is courtesy of someone who failed to realise what they'd got  putting steel strings on it, resulting in this -

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So...I'd greatly value opinions from the site membership on the best way to fix this. I'm wondering about mixing up some cascamite and dribbling it into the crack then clamping, or would thin CA be a better bet? I'm also wondering whether to take the heel cap off and put a brass screw or two in to make totally sure the crack stays closed.

The other thing I'm chewing over is refinishing it. There are a lot of knocks and dinks in the varnish so I was thinking of stripping back but question then would be nitrocellulose or oil? I've been impressed with the results some builds I've seen here have got with oil, thoughts/opinions anyone?

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Hi and welcome!

That's an interesting looking crack as it goes right across the grain pattern. It almost looks like the heel has been cut and reglued which would make a weak end grain joint. If that really is the case, trying to somehow clean all previous glue from the crack would be the first task which would require some improvising. If you can wiggle the crack open to see any glue residue that might give you a clue about how to proceed. If there's glue residue, using a tiny wedge to keep the gap open would help cleaning. Proper wood glue could then be squeezed into the crack. Again, that is if it originally was a glued joint.

CA is a good option as well as it will wick into the gap. Cleaning the crack would still be recommendable. If we compare CA with wood glue like Titebond in an end grain joint, it might be worth knowing that CA bonds to itself, often even better than to the actual material. So if it's an end grain joint, getting CA glue into the pores and letting it partially dry before applying the final amount might be a good option as well.

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8 hours ago, Bizman62 said:

It almost looks like the heel has been cut and reglued which would make a weak end grain joint

Look closer. The heel block is a laminated extension of the neck; pretty standard on acoustic guitars - you can see where it's been attached above the crack (the shadow of the original glue line is visible about one third the way towards the fretboard, and the grain pattern is obviously different between the neck and the heel block which makes it easy to see where the two pieces meet). It's definitely not an end grain joint.

The crack is with the grain, which indicates the heel has split under tension from the (wrong type of) strings, or it's received a bit of a brutal knock in a past life that's caused it to open up. I wouldn't use CA as it will wick away into the timber before it gets a chance to allow the two halves to set up, but rather mildly watered-down PVA (Titebond I, Elmers etc). Try and work as much as possible into the crack using something like a business card. If you've got a syringe handy, injecting the glue in will also help get it in as deeply as possible. Some gentle leverage on the neck may assist on opening it up enough to get the glue in there, but go easy - you're not trying to drive a car into the gap! Clamp from heel cap to fretboard to keep it tight and mop up any squeeze-out. Use some kind of protection to stop your clamp faces from denting the timber under pressure.

 

10 hours ago, Professor Woozle said:

The other thing I'm chewing over is refinishing it. There are a lot of knocks and dinks in the varnish so I was thinking of stripping back but question then would be nitrocellulose or oil? I've been impressed with the results some builds I've seen here have got with oil, thoughts/opinions anyone?

The traditional method would be French Polishing, but it is time consuming and laborious to do right, Wiping varnishes are easy and can look pretty good if done carefully. @Andyjr1515 did a tutorial that's about as good as it gets a while back which you might want to have a look at.

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26 minutes ago, curtisa said:

Look closer. The heel block is a laminated extension of the neck; pretty standard on acoustic guitars - you can see where it's been attached above the crack (the shadow of the original glue line is visible about one third the way towards the fretboard, and the grain pattern is obviously different between the neck and the heel block which makes it easy to see where the two pieces meet). It's definitely not an end grain joint.

"Laminated" - that's what I meant by "cut and reglued".

Line #1 is obviously a seam, the grain pattern doesn't continue on the other side of the line. Line #2 is what puzzled me, the line is straight but the small block looks to be from the same piece as the larger block.

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I'm with @curtisa in rather using wood glue, that wasn't too clearly said in my earlier post. Brushing some warm water into the crack first might help as it will go in more easily than glue. As the water absorbs into the pores of wood it causes a suction that will draw the glue in. Compressed air can also be used to push the glue deeper.

 

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Thanks for the comments both, looks like diluted PVA will be the way to go, and I do somewhere have a syringe from an old inkjet cartridge refilling kit that would be spot on for injecting it deeper into the crack. I did wonder whether CA might soak in and discolour the timber, and I really don't want to spoil that nice mahogany! Another thing I didn't mention was cleaning the fingerboard - I don't know how it got that way, but there's a load of grey-black gunk clagged all over it which resisted a wipe with white spirit. I may try warm soapy water and a stiff bristle brush, and if that fails the xylene will be coming out! I'm not quite sure what wood the fingerboard is, colour-wise it's the same tone as the rosewood back and sides (where it can be seen under the aforementioned gunk) but with a lot less figure to it.
As for finish, I'll keep chewing over what will be best - I do have a spraygun that I haven't used in around 20 years that I keep meaning to dig out, strip down, clean and try. on the other hand, maybe there is some merit in repairing the original finish. The machine head gears look a bit worn too, so I'll keep a look out on fleabay for a decent second hand set of Schaller or Gotoh classicals

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1 hour ago, Professor Woozle said:

I may try warm soapy water and a stiff bristle brush, and if that fails the xylene will be coming out!

Good old elbow grease is the way to go! Xylene sounds quite extreme to me, however I know nothing about it other than it's a solvent. Lighter fluid is also commonly used for tough grime. A single edge razor blade can also be used similarly to a scraper, it will take care of any deep fingernail grooves as well as thorough cleaning.

Don't forget to apply oil after cleaning! And I mean real oil like Boiled Linseed Oil, not the "Lemon Oil" which is basically mineral spirits with some scent and colour. The latter can work for cleaning, though, so it's better than nothing. The oil won't "moist" the wood but it will both make it look nicer and protect it from getting dirty too soon. As with any oils, don't skimp when applying and make sure every spot gets as much oil as the wood seems to want to suck in. Rub properly, then wipe it all off with a clean towel. After some ten minutes wipe it dry again as the wood may sweat the excess out. If needed, wipe clean a second time after a while.

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Xylene is the last resort, it's a good solvent and shifts most things but as is often the case with the best solvents, it's not good for your health - one to definitely use outside or wear an activated charcoal filter mask! I'll try the stiff bristle brush with soapy water first, it almost seems like the former owner not only nearly killed a fine guitar by putting the wrong strings on, but they regularly played with sugar-sticky fingers...

Yes, I do use linseed oil on fingerboards after I've cleaned with lemon oil or suchlike. I generally leave it on for a while and keep topping up the coating until the wood doesn't seem to be taking any more in , then wipe clean and give it a good rub with a lint-free cloth.

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SInce you're in the UK... I've heard that Crimson Fretboard Cleaner would be even more effective than lighter fluild as well as being more gentle to the wood. Then again, as they say that it's a centuries old recipe without any petroleum products I guess that it must be quite close to soap... Maybe boosted with turpentine? Their data sheet is available only on demand so it's not too easy to find out the formula. Anyhoo, soap and turps have been known for centuries.

You may be interested in other household mild cleaners as well. As I wasn't sure about the popular vinegar and baking soda mix being suitable, I did a quick search and found some interesting recipes:  https://www.tipsbulletin.com/how-to-clean-wood-furniture-with-vinegar/. Note that there's no soda in the recipes! The reason for that can be found in https://www.express.co.uk/life-style/life/1397980/baking-soda-why-never-use-bicarbonate-soda-on-wood-evg , where it clearly says that baking soda can stain high tannin woods.

Oh, and a tooth brush might come in handy in getting right down to the frets.

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20 minutes ago, Bizman62 said:

I guess that it must be quite close to soap...

What makes you say that? The product description makes it sound more like some kind of natural oil blend.

 

11 hours ago, Professor Woozle said:

Xylene is the last resort,

Too aggressive for the application at hand. If you're not happy to get it on your hands then it's probably best to keep it away from the timber as well. Xylene could easily react with the old finish, or if you have any plastics nearby (think binding around the body or fretboard inlays/markers) it may melt them.

Things at the milder-end of the scale like a damp cloth, lighter fluid, shellite, methylated spirits etc in combination with good old fashioned elbow grease should be all you need.

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43 minutes ago, curtisa said:

What makes you say that? The product description makes it sound more like some kind of natural oil blend.

Well... The Restorative is a blend of oils as they say. For the Cleaner they only say "The Cleaner is based on a vintage recipe used for over 3 centuries to clean stringed instruments of the highest quality."

Also, if you look at this comparison review you'll see that it a) can be spritzed and b) looks more like water than oil and c) the towel doesn't seem to get greasy.

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As a side note, the guy in the video later joined Crimson Guitars to work there for a while so take the praises with a grain of salt.

 

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To quote Baldric, "I have a cunning plan" - it's occurred to me that probably the best non-aggressive means of cleaning the fingerboard gunk will be lemon juice on an old washing-up scourer (well worn so it's less scratchy) and elbow grease. If that does the trick and gets the grot removed then I'll give the surface a rub-over with fine scotchpad, and then give it a good application of linseed oil. If my suspicions about the wood are right, then that'll hopefully show up if there's subtle grain pattern and confirm whether or not it's a lightly figured piece of Brazilian Rosewood.

I'll take some before and after photos too.

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2 hours ago, Bizman62 said:

Also, if you look at this comparison review you'll see that it a) can be spritzed and b) looks more like water than oil and c) the towel doesn't seem to get greasy

There are loads of products out there that appear to have the same properties as water (can be spritzed, looks like water, doesn't leave an oily residue on the cloth) that will be more compatible with raw unfinished timber as you'd find on a fretboard than water with soap (white spirit or naptha come to mind). To assume that the Crimson product is largely soapy water seems a bit of a leap.

FWIW here's another fretboard cleaner that uses very similar terms to sell itself as Crimson's cleaning solution - no petroleum distillates, all natural ingredients. The difference in this case is that they at least allude to a blend of plant-based oils as the primary ingredients in the product description:

https://www.musicnomadcare.com/Products/Fretboard-F-ONE-Oil-2-oz/

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4 hours ago, curtisa said:

To assume that the Crimson product is largely soapy water seems a bit of a leap.

I agree. During the day I remembered that I actually have a bottle of it! So now for the first time I opened the bottle and took a sniff. It smells like vinegar to me. So no soap as it won't work with vinegar! It has been sitting on the shelf for several years so something may have happened as there seems to be some tiny harder particles in the liquid. Not many but when turning the bottle upside down with a finger as a tap one or two tiny grains were felt for a moment. It also leaves a slightly oily feel on the fingers. Not greasy, rather like some real lemon/orange oil that is used as a cleaning agent. Maybe pine turpentine? There's recipes about using equal parts of white vinegar, turps and linseed oil as a cleaning solution for furniture. At least all of those were available 300 years ago.

Edit: I just got a bit of  "insider secret" from a guy who used to work at Crimson: The cleaner had a strong vinegar smell when they bottled it.

The difference between Crimson and F-ONE-Oil is that the former is a kit of cleaner and oil and the latter is an all-in-one product. For tough dirt I'd prefer separate products, for regular maintenance one single product will save time.

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Add lemon juice to that list. This afternoon, having a slack half hour, decided to try and clean the fingerboard with lemon juice on an old sponge dish scourer, and boy, did it do the job quick and easy! The first photo is before, the second is after a scrub with lemon juice, and the third was after I put a coat of linseed oil on to soak. I don't think the nut is original and it looks like there's a bit of glue spill, so I'll scrape back when re-nutting.

As to what the wood is, I'm still not 100% sure - I'm asking myself if it is indeed Dalbergia Nigra, same as the back and sides, but it's very lightly figured if so. Having said that, I think this is a mid-range instrument, so maybe Giannini were using a lower grade of rosewood for the fingerboard on these, which would have the desired tonal qualities but not quite the same aesthetic appeal?

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Lemon juice! Of course! It's an acid as well as vinegar and a commonly used for deliming coffee makers. I guess any residue of lemon juice tastes better in your coffee than vinegar residue...

Industrial lemon juice can even be better than vinegar for fretboards since they don't peel the lemons before squeezing so there's also some lemon oil from the zest included. And lemon oil is a very effective cleaner!

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Definitely better than the "lemon oil" sold specifically as a cleaner which has never even seen a lemon beyond the scent, that's for certain. I agree with the obviousness of what Dan Erlewine said in one of his books (...or perhaps just put his name against? Not sure how much ghost writing goes on in this game...) in that you start with the least aggressive solvent first, which is distilled water (or saliva) and work your way up through the solvents. Of course, knowing which one to stop at before they start attacking finish/materials is key. I've pretty much always got a spray bottle of Sinol (denatured alcohol/DNA) on the bench for all sorts of stuff since it's the most common. Anything like nitro is out of course.

Cleaning a fingerboard for me is always water/naphthalene/alcohol in that order. Lighter fluid is pretty good at reflowing human debris.

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Yepp. Back in the day I used to work as a salesman and there was quite many of lemon/citrus oil products in our variety, starting from screen wipes through rubber roller cleaner/regenerator to hand scrubs. Very effective, skin and environmentally friendly etc. But despite the alimentary origin citrus oils aren't something that you could drink as such! A couple of spoonfuls of cold pressed olive oil nourished daily is said to be healthy, the same amount of pure cold pressed lemon oil might be fatal if swallowed. That said, it's still safe to grate lemon peel on your food, the amounts used for spicing are too minuscule to ever cause health issues.

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Today I gave it a go with glue - I couldn't open the crack up enough to get a wedge in, but using my syringe I wetted the wood then dripped thinned PVA glue in, and flexed the neck as much as I was comfortable with doing to work it in. Clamped up with scrap wood for protection and wiped the excess glue off, I'll probably leave the clamp on for a week to give it plenty of time to dry.

I also took time to properly look over the state of the finish and I think I'll repair rather than redo - there's a few knocks need filling, some areas of scratching, and the end of the headstock has been abraded. I remember someone, possibly Martin Carthy, telling the tale at a gig about taking a treasured but road-worn guitar for refinishing; the luthier started asking about how the various knocks and dinks happened and MC (if indeed it was him I'm remembering telling this) realised that getting it re-laquered would be removing the guitar's history and changed his mind. I get where he was coming from on that...

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It's difficult for me to comment on the neck block repair without physically inspecting it, however I feel somewhat doubtful that anything more than a cosmetic repair can be achieved from the outside. The dovetail or tenon inside the body is where the real repair may lie. If you're able to manipulate the neck enough to get glue to work around the crack, it should be apparent whether the joint itself is good or not.

That said, steaming off the entire neck when the problem might simply be cosmetic is a mammoth task just to flick a stray hair out of your vision!

After a little reflection (and Internet searching) I found this to illustrate the point better:

https://www.tdpri.com/threads/full-crack-in-neck-heel-of-acoustic-bass-how-to-fix.847809/

If that crack extends through the dovetail (likely) then any issue is likely going to be hidden and/or delayed from reappearing. The tooled-up repair would be to remove the fret directly over the neck join, razor the lacquer around the seams, drill out a hole through the fret slot and force steam (Espresso makers are a popular choice, oddly) into the joint to remove the neck. To recover a Brazilian Rosewood instrument, this isn't entirely unreasonable. The bad news here is that PVAc glues are terrible to remove when doing repairs, as they don't clean up or work well with finishes/stains.

If the instrument plays, then put it into service. If it proves to be unstable or unplayable, then consider the hard route....possibly professionally if the right tools are not to hand.

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Given how difficult I found it to get the crack to open even the slightest amount, and it's been caused by over-stressing the neck with steel strings, I think the neck tenon joint is still sound. I'll see how it behaves when strung and like you say, if it stays stable and plays fine then nothing else is needed. I'm thinking of fabricating a new bridge and nut out of African blackwood, then I can get strings on.

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I have, mostly turning so I know just how quickly it takes the edge off tools from my experience of resharpening  the skew chisel frequently! I do love that chocolately smell it has, and it has a fine ringing tap-tone as well.
I did also consider lignum vitae for the nut and bridge, since I've got some of that in stock too. One piece is a small plank, nicely figured and I've wondered in idle moments whether it would make a good fingerboard, putting aside lignum's tendency to resist being glued...

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Lignum Vitae isn't much use on a guitar really. It is however, excellent as the sole of a plane or water bearings. My last teacher turned one for a water mill in Noormarkku, and said that it was throwing water all the while. It seems too far a throw from typical woods to be useful.

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Has anyone ever tried, I wonder? I know the traditional uses of Lignum are mostly related to turning (mallets heads, wet-use bearings and suchlike), and it is a lovely wood to work on a lathe given its oiliness, but its density (and the nice figure it can have) is what made me wonder if it could be used for a fingerboard if you could get glue to stick.

One of these days I may try an experiment with an offcut, treat it with solvent  to try and de-oil one surface then see if I can get it to glue to a different wood.

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