Gibson J55 Top Crack Repair Advice

[RETROROD]

I just got in a '73 J55 with a  top

crack along the pickguard extending North and South of the soundhole. I think it can be glued and cleated fairly well, but I would like some advice please.

The treble edge of the soundboard has curled up about 1/8' from the rest of the top. It takes quite a bit of pressure to try and match the edges. Should I humidify some to relax the top before glueing and splinting?

The crack extends north beside the fingerboard and south along the pickguard almost to the bridge.

This is a "classic" Norlin Gibson. Double X-over-,braced example. Also their first year of the arched-back dreadnought..It also has the 'tortoise binding' which is starting to disenegrate....Jeesh!

 

I have taken many pics in the afternoon sunlight and will provide some for clarification.

Rod

[RETROROD]

This is the top-bracing that I am dealing with...

[Hesh Breakstone]

Great pics Rod!

Yeah the tongue shim is what I would do here and I wish that I could draw and post what I am thinking of here but I never learned how to use any of the software programs that let's us draw away.

Anyway the tongue shim will be defined by butting against the upper transverse brace, the two sound hole stiffeners, and the sound hole.  This will give you an idea of the shape.  Grain direction is across the grain direction of the top, like a cleat.  Thickness around .060"isn and material could be mahogany, spruce or maple, I prefer hardwoods for this.  

Where the shim terminates with the sound hole I bevel it back around the sound hole like the inverse of how we bevel the top side of sound holes making a smooth curve.

It's installed of course in the inside and once clamping force is applied the crack in this region is forced back to level.

This is done after humidifying the instrument and attempting to get the cracks to close.

[RETROROD]

Thanks Hesh!

I think that I am clear on the tongue shim that you describe. I do have some spruce and maple patch stock.

I started on the pickguard removal last nite. Slow-going using a light bulb to heat the area. Spent an hour getting maybe 1/3 loose. I may go at it with the hairdryer/naptha method today! Since it is glued to the wood originally, are you on board with applying a coat of lacquer to the raw wood before re-attaching the guard?

Secondly, when starting the bagged humidification process should I align/clamp the curled split edge before the process or just let it do its thing for a week?

 

[Andrew]

I would go for the hair dryer, but I dont see the point of using naptha. The pickguard was fused to the top with a much more aggressive solvent - I dont think naptha would soften the joint at all.

A sealer coat of lacquer or shellac would be a good idea before reattaching it. I also really like the 3M adhesive sheets such as stew mac sells for this purpose.

[RETROROD]

Thanks Andrew! I finished up in an hour yesterday with the hair dryer.

Jeeesh, This thing was glued like "damnit"! If I 'wanted' it to stick, it would be 'falling off'!

 

It was particularly testy around the soundhole perimeter(the last to let go).

As carefull as I tried to be, there was some splintering of the top wood in the center area, but all was well around the outline of the P'guard.

I will post some before and after the humidification pics in a week.

I plan on lacquer-ing the bare wood and then using the 3M adhesive sheets that you mention. I also hope to re-attache the same P'guard if possible. Any caveats on that??

Thanks so much, Rod

 

She is bagged and sponged and hanging for a week

[RETROROD]

Just an update and a couple of questions...

The first and second picture shows the cracks after a week of bagged humidification.

The last picture shows some wood tear-out from the pickguard removal. I understand that this wood needs to be leveled and coated with vinyl sealer/lacquer before re-attacheing the pickguard with double-side adhesive.

What is the best stuff to use in filling and leveling the areas where tear-out ocurred?....Would epoxy be appropriate?

Also, any tricks or advice on removing the glue/wood residue from the back of the pickguard?

[Andrew]

I would try to save as much of the wood thats adhered to the pickguard as possible. Glue and clamp the tear out etc flat, then see where youre at.

Id shave the splinters off the guard with a box knife blade, then scrape it down carefully. Probably with the same blade. Box knife blades are basically long flexible razors, so you can bow them to focus on certain areas etc.

[Hesh Breakstone]

What Andrew said on the Naptha and using the 3M adhesive for reattachment of the guard.  I think that these guards were originally glued on and I only mentioned naphtha in case it has been removed before and reattached with double sided adhesive, then naphtha works great.

The bagging or rehumidification is our effort to swell the wood to hopefully close the cracks.  So no clamping prior to bagging the instrument.  Just remove the strings and bag the sucker.

The cracks may not close all of the way either but they also might so it's worth a try and pretty benign even if it does not close these cracks.  Instruments that have been recently cracked usually close all of the way with this process but the ones with long-term open cracks can be less cooperative and then we have to fill the cracks.

But let's see how she responds first to being bagged.

By the way my hats off to ya Rod for taking the time to carefully approach this very nice guitar and what it needs.  Good going!

Regarding under the guard the Martin method, currently... is to finish under the guard before reattaching.  It also behoves us to finish it well and make the repaired/refinished area level with the surrounding finish.  This when when and if the guard shrinks back the finish under the guard that will now be visible will not have a) a ledge and b) will be less visible with time.

By the way one of the guys at Elderly has been filling cracks that don't close with epoxy and tinting the epoxy to match what is already there.  Cleats are used too since filler has very little strength if any.  When I first heard of this method I turned my nose and closed my narrow little mind to it thinking no stinkin epoxy on my guitars.  But then I saw it done, participated in doing one myself and the results can be very good.  Food for thought.  Or simply use wood and lose your mind with the refinishing....;)

[RETROROD]

Hello Hesh, I could not resist the temptation to pull the guitar from the bag tihis afternoon. I see some improvement.....the curl has relaxed 'some' and the crack is somewhat tighter. Using my Oasis hygrometer, the rh is 51% inside the guitar. In an earlier post, you mentioned shooting for 75%....should I shoulder-on with the bag and sponge for a while longer? Is 75% realistic when read with one of these pocket hygrometers?

Or would the moisture content of the wood be a higher reading than the rh reading?

The question is open to all, of course.

Rod

[Hesh Breakstone]

Hi again Rod!

I took some applicable pics this morning of a couple of Martins that I am fixing cracks and a center seam on.  

One pic shows the 3/4" magnets and the caul and waxed paper and on this one the center seam is being reglued.  On the other pic the crack was off to the side and is already glued but now I am installing three cleats and using smaller magnets to clamp the cleats for a while.

I thought that these might help you out.

[RETROROD]

Just an update on the project (almost complete) and a hearty thanks to everyone for your great advice and time. The cracks were succesfully glued and splinted. I have strung up to pitch and everything is holding. After a truss rod adjustment the guitar sounds and plays amazing!

 

I have dutifully, reglued splinters and coated the bare area for the pickguard with 2 coats of sealer and 4 coats of lacquer, scuffing up to 320 grit. I have adhered the double-side adhesive sheet to the pickguard.

Now, my "Columbo moment"....Oh yeah!....just one more thing????

 

How should I finish up with the soundboard area before 'sticking down' the Pguard?(scuffed or  buffed) and how long should the lacquer cure before doing so? I really don,t want to 'puck-up' this part..... ;-)

 

 

[LARRY KLOSE]

IIRC, FF has a page on laying down a pick guard accurately on www.frets.com.

Larry