Deep into repair on a 1964 Martin 0-18 where I had to replace the top upper bout from the waist out (see pics) and wanted to see what tricks you folks might have regarding color matching the spruce. I've gotten a pretty good match on the grain etc. Normally I would have opted for full replacement but the balance of the top was in fairly nice shape so this slice and splice method seemed right. I don't want to overspray the original finish so matching the raw wood color is critical. Stories or suggestions welcome.
Everybody here has made good arguments for their points of view.After seeing the beautiful job you did on the repair itself,there is no doubt in my mind that the finish matching will be equally as well done.Good luck to you my friend.Regards Lonnie
A partial refinish, in terms of vintage integrity and vintage value is sort of like being a little bit pregnant. It's either a refinish or its not and the general value, in this catastrophic crunch, does not relate to the degree or extent of the of the repair. I am also concerned about the look - it's like bad car repairs - everybody can see them and knows the score. It alway looks like the owner couldn't afford to get a professional repair done.
A full top refinish is going to fix the repair line area and taking both pieces of spruce back to dead level and devoid of finish is going to give you a very good starting point to getting a consistent and appropriate repair that will increase the value of the instrument in the long run anyway.
As for leaving the guitar out in the sun with one piece of unfinished spruce and one finished piece of spruce glued side by side - you are inviting differential rates of drying/expansion and contraction between the two pieces and failure of the joint area.
Refinish the top with the same schedule that Martin uses and shade the finish coats a touch lighter and let time take its toll. I'd avoid staining or treating the bare wood unless that's how the original finish was done. Rusty.
I agree with you on leaving it out in the sun, not a good idea, I laughed at the suggestion when I heard it too. I still think the need is there for some kind of color balancing no matter if it's full or partial refinish. I'm leaning towards coloring shellac like George suggested. I've used that method before with good results.
The Idea of leaving it in the sun (preferably inside behind a window) isn't so outlandish in my estimation. Chasing the UV effects on spruce with stains and pigments will always lead to angle issues and other frustrations. The "free" color the sun has to offer is a good place to start. A strip and refin on what looks to be a 60's 18 of some sort won't get you kicked out of many snob clubs, but it is more work than a good/fair touch-up that aims for functionality without breaking the bank. (Unless you're doing a neck set/bridge reglue)
Ian has hit on one of my issues with the complete refin. The bridge has never been off and is still perfectly sound and additionally the pickguard is firmly attached (to bare wood) so I avoid any of the possible pitfalls of their removal by partial refin. The neck is already off as that was needed to replace the side properly but Martin necks come off so easily anyway. Tomorrow a sample piece of spruce gets a tan and I'll see what results.
A good tan might take a couple weeks. Make sure all of your prep for finish is done as any after sanding will ruin your hard fought tan. A bottle of lacquer in the window at the same time is a good idea as well.
So here we are a few days latter with the sun tan results. Started with Taylor Swift and was hoping for John Boehner and still have Taylor Swift. Can't wait that long, so I'm experimenting with the tea, black with no sugar, and it shows promise. It too is slow but very controllable, although I'm considering coffee. The question now is what kind ? I love Kona for the taste, but darn it if Columbian doesn't smell better.
I got a flier in the mail yesterday from International Violin. Their 2 oz. bottles of oil varnish are on sale.
If it seems to be taking too many applications consider concentating further by reboiling and adding fresh tea. In the past I have started with 15 tea bags in 2 or 3 cups of boiling water then removing the old bags, microwaving to boil again and add a fresh tea in a similar amount.
To dry the work piece faster I use a heat gun set on low (being careful, aimed from a few feet away) rather than compressed air as my compressor cycles endlessly...
Zinnser makes their bullseye shellac in an amber shade.I recently used it touch up 1920's martin around the bridge area as someone had put on a classical style bridge that was way over sized. I think it would match that shade quite closely.
So I thought I should follow up on the '64 0-18 repair I posted about last month. I tried so many tints and stains on this thing without real success. The end result was a light overspray of the entire top proved unavoidable. Rusty, you hit the nail on the head on this one for sure. One thing I did find helpful was Dichromate. It's used by violin guys to age wood and it works great. Mix it with water (carefully as the powder is dangerous) and apply as wash coats with ample drying time between coats, until the desired aging is achieved. Ended up doing a light amber overspray over the entire top as well as the back and sides. Interesting side note, the first comment from the client was " Why did you overspray it?". It sounded great. Here are a few pictures before strings.