Stabilising lifting finish... Anything that doesn't stick to superglue?

DartmoorHedgehog

OK, I'm back on a project I've discussed on here previously (regarding getting a logo transfer made).

Briefly, it's a Daisy Rock Heartbreaker that's had a bit of a hard life (had big chunks of wood missing etc).  All the finish on the neck had cracked and started to come away from the wood.  It's quite thick so we stripped it all off most of the neck with heat gun and scraper (leaving a really quite nice neck), but at the moment we've left the front of the headstock.

Obviously there are various ways to deal with the headstock (as discussed in my previous thread), but before we go into refinishing it and trying to recreate the logo (or not) it seems like we may as well try stabilising what's there.  If it fails we'd just be stripping it anyway so nothing much lost except a bit of time.

My plan is to inject superglue under the cracks with a syringe then clamp the whole thing flat.  If that works then lightly rub down and put another thin layer of clear coat over the top.  But what can I clamp it with that won't just stick to the squeezed out glue and pull the lot off when I unclamp it?  Sheet of glass?

Hopefully this picture is good enough to show what we're up against - pretty much everything is still there, it's just got these long cracks and each section is slightly lifted/curled at the edges.  Seems like it ought to be savable (and worth a try both because of the awkward paint matching and losing/reproducing the logo)



EDIT: I should add that this isn't intended to be an invisible restoration - the body has had massive chunks of wood replaced and lots of chips that will be finished in a contrasting colour rather than trying to match the original.  So keeping the "character" of the headstock but stopping it all falling off is the goal.

WezV

superglue (CA) won't give you much time to wick in and clamp flat.  The thinner stuff wicks in better, but will definitely  be dry before the clamps are tight.  I'd use it if just stabilising, but not when clamping flat is required

first thing to do is a dry clamp with no glue.  i'd advise a bit of thick perspex as  the caul so you can see what is going on. Obviously it could all just crack and flake off when trying to clamp flat.  if it doesn't, you can try thinned epoxy or a slower setting CA glue - obviously with a non stick barrier between caul and headstock - waxed paper, non stick baking parchment etc

 

DartmoorHedgehog

Thanks @WezV ;
I can push the edges down with my nail and it doesn't crack so I think it's not going to disintegrate (but good point about a dry run first to prove it).  The CA I've got is very thin stuff that takes a few minutes to set (I use it to paint on my nails to stop them wearing through when playing in the rock band - I hate using a pick) so I reckon I'd have time to clamp it (perhaps if I did one crack at a time depending on how quick I am with the syringe).  If baking paper would work as a non-stick layer I think I've got some of that.

One other idea I had (instead of gluing) was to put a clear sheet over the whole headstock, held down by the tuner nuts.  But I don't think there's enough spare thread to fit a rigid enough piece of sheet.  Or even just a sheet of thickish sticky clear plastic.

WezV

Just test a drop of glue on the baking paper as different types seem to work well with different glues

Gagaryn

Polythene. If they make the superglue bottle with it, I would have thought that would be a good shout.

Winny_Pooh

I'd personally wick the CA into the gaps and push each bit flat as you go to level it out. Then use gluboost on the whole headstock as a thicker layer, then sand flat and polish if you have the time.

DartmoorHedgehog

Gagaryn said:

Polythene. If they make the superglue bottle with it, I would have thought that would be a good shout.

Not sure about that - it stays liquid in the bottle as long as the lid is on and the air doesn't get to it, but when it sets it does stick to the plastic, certainly in the nozzle.  But thanks for the suggestion - I'll experiment a bit with various methods people have suggested before I tackle the actual headstock.

BillDL

It's a pity the Screwfix No-Nonsense superglue comes in the container it does, because it is nice and thin, wicks into cracks and under cracked lacquer very well, dries clear rather than going white and crusty from the moisture absorption as it cures like some do, and has a fairly good length of open time before it starts thickening. The hole in the nozzle of the container is too large to do really fine and accurate wicking in and the design of the cap makes it prone to clogging up.  For fine work like this you really need a whip-tip or, if you are very careful and have a steady hand, you can sometimes make a good enough job by dipping a needle into the glue and using that to run along the crack or drop a tiny blob into a small ding.

My worry with clamping down the raised and curled edges of the lacquer after wicking in superglue would be the squeeze out.  You can wipe something waxy around or either side of something you are drop filling (or even mask it with something like insulating tape) so runs don't stick to adjacent areas, but you would be clamping the filled cracks (presumably one at a time) and the squeeze out would spread thinly and be very hard to remove when it's dry.  Where you have overfilled something you can wrap some tape around each side of a razor to act as a safety spacer to scrape down the hardened glue and then mask off either side of the area and finely sand down the thin remainder then polish it to a clear gloss.

Trying to wick superglue into one crack at a time and then press down the curled edges of the lacquer while spraying activator would be practically impossible without having a dozen very skinny fingers.  I don't think you could work your way along a crack gluing it down in stages as you can do with binding, because you would end up with transitions where the glue wicked under an adjacent area not pressed down and you would have small sections that were crisp and wouldn't bend to be held down.  The glue would be all over your fingers anyway, or you would have bits of latex from the gloves stuck to the glue.

I've just fixed multiple longitudinal lacquer cracks that had curled up on the soundboard of an old Eko acoustic guitar with a laminated soundboard.  The lacquer was polyurethane and the edges of the lacquer were razor sharp.  The lacquer would have cracked had I managed to press it down enough to get a reasonably level surface.  If I had sanded the curled up edges of lacquer down flat I would have risked sanding through the top veneer of the laminated board.  I tried warming the lacquer with a hairdryer to see if it would make it pliable enough to bend the curled up edges flat, but it didn't.

The edges of all the cracked lacquer were curled / raised up in the same direction, and the cracks were very straight, which was in my favour because I was able to mask off quite closely either side of one crack at a time and prop the guitar body up at just enough of an angle where the thin superglue wicked under the edges without running into adjacent areas.  When dry I just left the masking tape (electrical insulating tape) in place and used a bare razor as a scraper to effectively shave off the curled up edges of the cracked lacquer which was now filled underneath with clear superglue.  I could then very finely sand the slightly raised bead of superglue then remove the masking and polish the seams down to an absolutely clear glaze with T-Cut.  The filled lacquer cracks are never going to be invisible because they are now very shallow domes running the length of the cracks like the meniscus on a drop of water.  You see them when the light is at a certain angle, but straight on they look a whole lot better than they were.

In your case that logo may present a problem if it's on top of the lacquer or the layer of lacquer over it is very thin.  Any scraping, sanding and polishing of superglue fill (or squeeze out) may start removing the logo.

I have a bunch of clear flexible plastic sheeting that was used to knock together visors for medical staff during Covid.  It's probably polycarbonate that, when about 10 are stacked together, has a slightly smoky tint, but on their own they are just about clear.  It can be cut easily enough with scissors or a Stanley knife, and you could probably round the sharp cut edges with very fine sandpaper and T-Cut.  The material is 0.5mm thick.  It wouldn't be inflexible enough to actually press the edges of the cracked lacquer down using only the nuts for the tuning machines, because it would bend in between over the raised edges of the lacquer I think.  I would be curious to know whether it could be glued and clamped down with a flat caul as a clear headstock overlay using epoxy that is known to dry absolutely clear.  That might work, but I don't know if epoxy would stick to this material.  I can post you a few sheets if you PM me your address.

You could possibly even use the much thinner overhead slide projector transparent sheets that can be printed onto as a thin clear headstock overlay if it could be glued on without bubbles.  I have a bunch of them also.

DartmoorHedgehog

Thanks @BillDL .  The CA glue I've got is very thin and does dry very clear.  I was planning to use a 1ml syringe with a tiny flexi "needle" to get under the cracks, but now people have mentioned it I'm thinking it might just wick in enough on its own. 

Not clamping it down is certainly worth thinking about - all I really want to do is stop it all falling off rather than making it look perfect (the rest of the guitar is pretty "characterful" - it's had a life) and the clamping, with potential to stick to the caul, is certainly the bit I'm most worried about - hence the thread.

I'm not sure if the logo is printed right on top of the finish or whether it's under the clear coat.  If it's on top then you're right that scraping the ridges would be risky - but I'm not sure it would be necessary if wicking glue into the cracks stabilises it enough.

Sticking some sort of laminate sheet over the whole thing was another possibility I was looking into - but my main concern with that is ending up with bubbles.  Worth thinking more about though.  Thanks for the offer of some plastic sheets but I'm sure I've got some suitable thin stuff somewhere that I can experiment with (or even salvage the side of a plastic bottle for something a bit thicker).

Perhaps I'm over-thinking it and just wicking some glue into the cracks and a light clean-up with scraper and/or acetone would be all it really needs.  To be honest, the battered character of this thing is part of its charm so it's definitely a "get it playing well" project rather than a restoration - daily driver not concours as it were.

DartmoorHedgehog

OK, I did something with this over the weekend...

Decided not to try pressing it down flat after all, but just to wick thin glue into the cracks to stabilise it (well I did press the worst bit down a bit with my nail while it stuck).  Which worked well - but obviously a little bit of glue on the surface.  "Easy, just rub it all down with some wet and dry" I thought... then without really thinking about it properly wrapped the paper around a block of wood.  And of course (in retrospect) it took off all the ridges of paint that I'd decided not to press down, leaving bare gaps.  Arse.

But looking at the positives, it's now flat and stable, the logo is still there, and it has quite a cool "flame" effect where the gaps have been exposed.  To go with the idea of painting the repaired areas of the body with a contrasting colour, it may actually turn out quite cool to fill in the "flames" in the same colour and clear coat over it.  And if it ends up shit we can always strip it all off and repaint it (but then we're back to the "what to do about the logo" decisions).

BillDL

That's a pity.  It might be possible to find a felt-tip pen in a matching shade of purple, or a craft pen designed to be indellible and not rub off, and "paint in" the lines where the wood underneath is showing.  Ordinary felt-tip pen ink tends not to stick too well to superglue though because it's like using one on glass.  If the headstock face has been sanded to provide enough of a key on the polyurethane lacquer for clear nitrocellulose lacquer to bind to it well enough you could overspray the whole of the front of the headstock in clear gloss.  The problem with that (and also filling in a ding with felt-tip and dropping insuperglue) is that sometimes the lacquer or glue can darken the shade of pen, or in some cases cause the pen ink to dissolve and run leaving a patchy fill rather than an opaque fill.

Winny_Pooh

I'd use a posca pen to "paint" and then finish over

BillDL

I must commit the name Posca Pen to memory, because there are times I could definitely have used them.

DartmoorHedgehog

Yes, thanks folks.  I think it might actually look quite cool with the "flames" in a contrasting colour - that's the plan with the repairs on the body anyway (which was in a real mess with big chunks of wood missing as well as just paint damage).  The damage is part of its story anyway (briefly, it was smashed up by a friend's ex after a falling out - quite appropriate for a Heartbreaker - then put in a storage container and found years later after she emigrated and asked me to help sell off some of her old stuff).

JayGee

For me that sounds like it’s just begging for a Kintsugi style treatment with the missing/damaged portions filled in with gold…

DartmoorHedgehog

JayGee said:

For me that sounds like it’s just begging for a Kintsugi style treatment with the missing/damaged portions filled in with gold…

I think it'll end up something similar.  Probably not gold though - more likely something bright like pink or green.  We'll see.

Sesh

I missed this thread the first time round, but for future reference PTFE sheet is good at not being stuck to.  I see eBay has small quantities at pocket money prices. I suspect wrapping the contact points of other objects with plumber's PTFE tape might work, but I've not tried that.

Looking forward to seeing how this turns out.

DartmoorHedgehog

Yeah, thanks folks.  I think it's going to turn out interesting.  Not sure when it'll get finished but I'll definitely post an update when it does.  My daughter bought it from our friend (the original owner) and I think she wants to do the arty bits.  The bulk of the repairs are done now so it just needs finishing next time she's here (she's a uni student at the moment).

paulnb57

If you did want to go down the gold route, Posca do gold paint pens…