MIMF

Hi

I have a crack in my top in the upper bout and I want to inlay an ebony cross into it to stop it from cracking further. I have tried cleats and hide glue but it just gets bigger. From what I see top inlays can dampen the sound. Will I have an issue if its in the upper bout?

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I don't have enough experience with this sort of thing to do anymore than guess, but some extra information may help those who do. . . First, posting a picture will go along way towards getting some good advice for repair and ramifications. Is this a guitar you built? Is the crack spreading after cleating or just opening up again. Was the top domed and at what humidity was it glued on?

Ya sorry I forgot to include some details. Here is a picture from my phone, sorry its the only camera I have right now. It is a guitar I built around 40% humidity. At one point the humidity dropped to around 30% and the crack started. I rehumidified it and the crack had almost completed sealed so I cleated it and then put thin hide glue on the top and let it dry and proceeded with shellac over the top of that. The crack has opened up a little bit but mainly it is that it is getting longer that I am worried about. It has almost doubled in the last few months.

Here is the pic sorry. I really didn't think it would have spread past the brace and cleats.

I am sure that has frustrated you.

As I look at it, I wonder if the edges have rolled up a little, and it has slightly raised.

If that is the case, a splint might fill the crack well. After placing the surface splint, make sure it is reinforced inside with a cross grain cleat. A few days later, when every thing is dried and back to normal humidity, sand the surface flat over the repair, and fix the shellac damage.

It does seem raised or rolled up a bit. How easy is a splint to do? Would it not be easier and look better just to inlay something into it?

A black inlay will draw everyone's eye to that corner.

A splint is easy.

You take a sharp thin knife like tool, cut a slight V shape into the surface. You take a similar colored piece of spruce and make a matching V. Use hot hide glue and slip the splint into the groove. Hopefully, the depth of the splint is such that it is a little above the surface when you are finished. After it is all dry you scrape or sand it down flat and refinish.

One of the reasons this works well is that the spruce is easy to compress. That means you have a lot of lee way with a less than perfect fit.

This repair is actually quite simple. It just sounds difficult.

It produces a nearly invisible repair without much difficulty. The slight color change from old to new shellac is what will show the most.

Edit--by a slight v shape, I mean a groove that is about 1 or 2 growth rings on a tight growth of spruce.

Drawing there eye to the corner is not a bad thing if it looks neat and clean. I've made so many other mistakes it might distract them from seeing it.


It's the shellac I worry about. I had another piece where I spliced in a section near the binding on the other side and although the top looks ok there is a notice in the finish as it has a much lighter spot. Maybe though I just need a few more light coats on it to blend it better. I got it strung up for the first time and I want to play it a bit as it was a long build to finish with my newborn and work taking priority. Once I get it setup and play it for a month or two then I was thinking I might start fixing all the little mistakes or at least any really noticeable ones. The crack worries me though if I leave it that long. My initial plan was just to fill it with hide glue and then fix it better down the road.

I'll look at the splice again maybe I can do it quickly and just worry about the refinishing part later.

I agree with Steve. Splinting will fill the gap and draw the eye less than an inlay. I use a knife with a wedge shaped cross section and use it to compress the wood on either side of the crack slightly and give the opening a wedge shaped cross section. I use a wedge shaped plane shaving to fill the crack. No wood is removed from the top, and a very thin piece of wood is used to fill the gap.

Pop the bridge off and re-finish the whole top?

I've refinished the top 6-7 times already over the last year for various reasons. Most of them because I was trying a sunburst. Not really willing to do it again. Not yet anyways.
For now I'll just do the spline maybe and finish it quickly with a small brush maybe. In the future I want to redo the purfling so I might just pop the whole top off and replace it or refinish it then

John Nephin wrote:I've refinished the top 6-7 times already over the last year for various reasons...

Perhaps repeated refinishing (with inherent scraping/sanding) thinned the top too much to maintain structural integrity? DAMHIKT

Seems ok so far.

Once you string it up and start playing it, the likelihood that you will go back and fix little mistakes goes way down. As tempting as it is to rush the last little bit so you can string it up and hear it, it is even more difficult to bring yourself to take the strings off and do cosmetic repairs (especially since, by that time, you are already planning out the next one).