Carved top starting to split apart, please help me save it!

Hello there fellas, i completed my second build a couple of months ago and i was pleased with the result, but since i am in no way a woodworker i believe i learnt a lesson as to what not to do when gluing two slabs together.

I glued four ash slabs to the solid mahogany slab with the grain orientated at a 90 degree angle to eachother, as well as having the ash joint weakened by the pickup hole

It gave me some tuning instabilities but it seems to have settled now (doing most of the work outside probably contributed to the wood movement, as a welder i am used to metal, it just dont move as much :D

So im looking for some of your expert opinions to mend the current damage and any steps i can take in order to prevent any future problems when humidity returns with the summer
Here's a picture, mahogany base is 30mm (1.2in), ash top same thickness but with an agressive carve all the way around, down to 10mm (0.5in)

https://i.ibb.co/59f5mx7/20220104-203309.jpg

I was thinking of perhaps instead of hiding the defect i could accentuate the split with a dark glue mix and add something like a walnut bow-tie as a suture

And yes as you can see i havent treated the body yet with any kind of finish, i've just kept it indoors, playing it as i dare not expose it to sudden temperature changes and cause further warping, im thinking of going all out with linseed oil and really saturate the wood instead of using some kind of hard varnish, it would become more scratch sensitive but more stable against humidity swings, and it would allow for an easy maintenance down the line, am i thinking right?


I didnt really want to do the finishing touches before i was totally happy with the neck
That was a good call since i aim to sand down the neck profile to more of a D shape, and remove 2mm total thickness as well as dressing the fret ends a lot more.


Pardon the wall of text but i feel obliged to explain myself amongst you fine people if i am to expect some expertise and tips! thanks


If interested, this is a link to the full build https://www.buildyourownguitar.com.a...ad.php?t=11494

I made a couple paper bowties and painted them with some acrylic burnt umber (i really like my 'Van gogh acrylic 10 pcs set by the way, i did use a light brown mix of it to fill the pores in the ash, perhaps i should fill the mahogany pores as well to keep it as stable as possible too

https://i.ibb.co/JFv5v7L/20220104-220514.jpg

Here you can get a visual of what kind of look im thinking of, functional and stylish (if done right), im sure some of you have some great and aesteticly pleasing tips, bring it

You've made a number of errors here.

Firstly, you've glued the ash on with its grain going cross-wise rather then end to end in line with the neck. It's much weaker in that direction and the torsional forces from the strings put a lot of compression force on the top, which the ash is less able top resist in that orientation. That helped to crack the glue line.

Secondly, you haven't put any finish on and the ash has dried out and shrunk as result. Probably the same with the mahogany body if there's no finish on it. So you've probably got differential shrinkage as the woods will shrink at different rates. As the woods have shrunk, they've pulled apart at the weakest join on the ash top, that between the neck end and the bridge end. The much larger surface area between the mahogany body and the ash top means that its glue joint is was stronger than the thin edge to edge joint between the ash sections, so it was always that which was going to go first.

The good news is that the ash probably won't shrink much more, if any. So I'd fill in the crack with whatever you want, sand it smooth and then put a clear finish over the body, top, back and sides

Any finish will help seal the wood and make it less vulnerable to temperature and humidity changes, both the mahogany and the ash.

You could use boiled linseed oil, TruOil, poly, acrylic etc. Anything that sets hard and forms a vapour barrier. Three or four applications of something like TruOil will seal the surface.

I'd also recommend putting the same stuff on the neck. The fretboard looks quite dry to me, so I'd give that a good soak with lemon oil or mineral oil (chopping board conditioner) maybe every 3 months to stop it drying out too much as the board can shrink enough over time to make the frets loose.

I think that these measures should stop any more damage, but short of removing the top and replacing it with some more ash pieces or a veneer (veneer would be very difficult with the carved top), I can't think of a way to restore the looks.

A pickguard would cover the bottom join and if you are good at mixing the acrylics then you might be able to paint the glue in the crack to match the ash grain to at least make it less noticeable.

Anyone else got any ideas?

Thanks for the points Simon, yeah i am aware of my mistake by orientating the grain absolutely wrong, it taught me a lesson tho, i am not in any way used to working with wood, but i really enjoy it compared to working with steel, might switch profession, but you gotta admit it was difficult not to place the ash in the orientation i did, the grain really looked great that way

;) yes the fretboard is dry and my plan was to start soaking it with boiled linseed oil also, but you mentioned lemon and mineral oil, should i refrain from using linseed on the fretboard and opt for lemon or mineral oil?

And you would personally prefer a solution in which i dont accentuate the split in order to add bowties? i was thinking filling it with a dark filler and figure out a suture that is pleasing to the eye

Furthermore if i were to add some kind of bowtie i could make the routed hole very deep almost breaking through the mahogany, that ought to add some stability more than just filling the crack

I thought about hiding it but i think that my mistake really should be highlighted and have the solution visibly displayed on the instrument itself, thats why i am so stubborn about bow-ties

I'm afraid this one's a bit out of my league tbh, but it sounds like you're pretty set on both accentuating the mistake and adding the bowties? I figure if that's what you want to do you may as well go for it, but I can't offer any practical guidance as to how to go about it. (though there must be a tonne of info on YouTube?)

It looks great btw, and I can see why you chose to glue them together like that. Just unfortunate that the nature of wood worked against you!

Boiled linseed oil polymerises, so you’ll get a hard finish in the fretboard surface if you use that. Some people use unboiled linseed oil, which can harden over time but is mainly a fairly thick oil. Lemon oil is the most common oil used on fretboards and mentioned in guitar care articles, but other similar mineral oils can be used. It just needs to be absorbed by the wood to make up for lost moisture, but not remain on the surface so that it makes your fingers oily. As a result, lemon oil or mineral oil is light enough to evaporate over time, which is why you need to oil the board fairly often. Here in the UK you can normally get by by doing it once a year, but i know in warmer, drier climates, you may need to do it every three months.

I don’t know enough to know if bowties will do much good in this instance. I think you’ve had the worst of the shrinkage so sealing the surface should be enough to keep things stable. But you do want something firmer than wood glue, say epoxy, in the crack to give a more rigid filling that can spread any compression loading between the pieces of ash.

Thanks guys for the inputs, i've decided to skip the bowtie idea and instead carve down some of the ash in the shape of a f hole and fill it with a light brown acrylic layer or i might utilize some of my mahogany veneer, going to make some more tests and hear what you think

And as you suggested, Simon, i will fill the gap with epoxy resin then paint over it

I made two paper test pieces and glued them in place in order to visualise, what do you reckon?
https://i.ibb.co/r3PmF3g/20220105-011730.jpg

Quote:

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Originally Posted by Simon Barden

Boiled linseed oil polymerises, so you’ll get a hard finish in the fretboard surface if you use that. Some people use unboiled linseed oil, which can harden over time but is mainly a fairly thick oil. Lemon oil is the most common oil used on fretboards and mentioned in guitar care articles, but other similar mineral oils can be used. It just needs to be absorbed by the wood to make up for lost moisture, but not remain on the surface so that it makes your fingers oily. As a result, lemon oil or mineral oil is light enough to evaporate over time, which is why you need to oil the board fairly often. Here in the UK you can normally get by by doing it once a year, but i know in warmer, drier climates, you may need to do it every three months.

I don’t know enough to know if bowties will do much good in this instance. I think you’ve had the worst of the shrinkage so sealing the surface should be enough to keep things stable. But you do want something firmer than wood glue, say epoxy, in the crack to give a more rigid filling that can spread any compression loading between the pieces of ash.

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So its really a matter of preference as to which oil to use? by the way i may have misnamed the oil that i have, brand name is Teak oil but i assume it mostly consists of linseed oil, or am i wrong?

I did buy a bottle of teak colored oil stain, supposed to get very hard surface but i really didnt like the way it made both the ash and mahogany look, it lost character, especially the ash, now when oiling up the ash using the regular teak oil it really gains depth and a more natural color

You can see in the pictures that i've posted, within the carve of the ash above the low E, the color change in that area is from testing the stain, i can add some of the regular teak oil to the opposite side so you may see the difference

Some comparisons, the camera really doesnt do the teak oil justice
https://i.ibb.co/ZW6BWCC/20220105-015734.jpg
https://i.ibb.co/2gDMPBh/20220104-230222.jpg

I will re-sand the entire thing when the final adjustments are done :)