Crawls Backward (When Alarmed)

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Refinishing Spruce Top on 1931 Martin O-18T Tenor Guitar

The new bridge is finished.  If I keep making enough of these things, one day I'll get a really good one.  But that will take 50 years for me to get that good and I probably won't live that long.

It took me three blanks to get one that was reasonably decent.

There it is with one of the pictures of an original one that I used as a general guide.  It's not perfect, but as the justly famous Sven of Argapa says "there are little mistakes, but that's what makes it personalized."  Or something like that.

At any rate, it's far better than the hacked-up on that was on the guitar originally.

When I first got the guitar, it was clear that a lot of finish was missing from the top.  I figured there would be enough left to clean and polish out.  Some missing finish would be ok and would look cool.

But as I cleaned all of the filth off, the truth was revealed.

There's hardly any finish on it at all!  What you see is all of it.  Some around the bridge and a couple spots here and there.  As much as I didn't want to do this, I'm going to have to refinish the top.

I hate hate hate to touch the finish on old instruments, except for cleaning, polishing and a small touchup here and there.  But if I play this guitar as is, I'll just proceed to grind dirt back into that beautiful spruce.  (Which is probably 90 or 100 years old to begin with.) So refinish it is.  Fortunately, the back, sides and neck are in ok shape.  Only the top needs to be finished.

Before I do any prep on the top, I figure I have an opportunity to at least brew up some lacquer toner that will match that lovely shade of finish that's still on the top.

I made up a small batch - a few drops of amber Color Tone liquid and even fewer drops of medium brown.  Here's the final test on a scrap piece of spruce - the blotch on the left is the winner.

Then I very carefully took the remaining old finish off with lacquer reducer, and sanded the top.

I may have shown some of the awful scratches around the bridge that were made when the original was taken off and replaced.   At least this was an opportunity to get them off.  Or, at least, made less noticeable.

I didn't dare go lower than 120 grit paper - I used that sparingly on the scratches and places were dirt was ground into the wood.  I couldn't get all of the deep gouges out, but it looks much better than it did.

Then I used 220 and 320 for the final sanding.  Look how white the spruce is!  How wonderful it must have been to have worked at Martin in the 1930s - imagine the smell of spruce, mahogany and rosewood mingling everywhere as the craftsman did their work. And this little guitar was one of the instruments they crafted.

The grain is just wonderful.  You can also see how Martin glued the top so the tighter grain is near the center seam, and the wider grain is further out.  (The tape is to mask the bare wood where the pickguard and bridge will go after the finish is done).

I mixed up some blond natural shellac I use as a sealer/wash coat.  It's about a 1 to 1.5 pound cut.  Two thin coats did the job - I used a high-quality taklon artist's brush.

I considered using varnish or shellac as the finish period, but I decided to use nitro lacquer since that's what Martin originally put on it.
Finally we journey to the Crawfish Instruments spray booth - as big as the great outdoors.  I had to wait several days to spray the lacquer because it was extremely hot and humid.  Once the humidity dropped below 60 percent, I ran outside and went at it.

This is just the first coat of toning lacquer.  I'm using a Preval sprayer - I don't have a spray gun (yet), so this will have to do.

The color is not bad, I think.  

I'm thinking 2 coats of toner, and then 7 or 8 coats of clear.  We shall see.  This first coat is still drying as I write this.

As an aside, this is my 500th post on this blog! 

 
 
 
 

Post a Comment 2 comments:

  • Anonymous said...
    September 12, 2013 at 12:38 AM
    Hi there,

    I am currently working on a Vintage D-28 Martin. I have a sand thru on the lacquer. The sand thru is an oval shape and I can't seem to color match it. Was wondering if you had any suggestions. Can send pics if you need to see. I was contemplating refinishing whole top so it's uniform, but the question is will it ruin the value? Thank you for any words of wisdom.
  • Yr Fthfl Blggr said...
    September 14, 2013 at 1:26 PM
    Hi - I'd be happy to take a look...please send me another comment with your email address.

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