Weather-beaten.

 I had some time recently to revisit the electric bodies I've been seasoning for some years after an extended period of exposure to the elements in a harsh Canadian climate.  I finished this one by very lightly cleaning and sanding with 600 grit paper and applying one extremely thin coat of polymerized tung oil just to set the patina in place. I expect new scratches and dents to appear.  Right now it's loaded with some pretty raw-sounding GFS overwound pickups.

Nuts.

I had occasion to retrofit a nice contemporary Gretch with a new bone nut recently, and thought I'd discuss my thoughts on this important component of playability and tone.  The owner and I scratched our heads for a minute or two, trying to decide if this was factory-original equipment or not. It's a synthetic compound and there wasn't a whole lot of care put into shaping it.  It functions.  He didn't think it looked quite right.

It's flat on top and doesn't echo the radius of the fretboard. It's deeply slotted in parallel lines. (For reference, those are *big* strings. 12-52's.

The nut isn't solid, and it's held in place by some adhesive. I prefer to use less glue. One shouldn't need to hammer repeatedly to crack it free. Just a little rap with a block of wood and the amount of pressure you'd use if you were knocking on a door.

That's less than ideal...   The ragged take-off point give the string a mushy and inconclusive place to start. They're buried pretty deep, too.

Clean off the old glue!

The slot varies in width from .227" on the treble side to .239"on the bass. It's good to measure these things before taking a file or sanding block to the bone blank. -Make the bone blank an even thickness and by the time it fits nicely in the tighter side of the slot it would be flopping around on the other side. It's not hard to match a little taper like this and it's less stressful than trying to score and cut the nicely lacquered headstock overlay.

Filing to width involves scribing a line to work to, then repeated trial fitting until it feels right.

The pencil has been planed down to half it's usual thickness. It rides the surface of the frets and acts as a guide for slotting depth and preliminary shaping.

The new nut has a more graceful profile that follows the shape of the board, slightly higher on the bass side.

The bass strings only need to be seated about half their diameter. Excess material surrounding them can hang up and cause tuning issues. On bone or (legally obtained) ivory that material can be brittle and crack off.  All edges should be nicely radiused with no sharp corners! The profile should be smoothly rounded and provide a good bearing surface, not too long, not too short.

Slanting the string slots a little towards their respective tuning posts helps tuning and prevents premature wear. Two tiny drops of CA glue hold it in place, ready for play!

The finish line.

Here's a late-'90's Guild F47 that came in for some finish work recently.  It's got some localized pick wear.

Pretty vigorous strumming!  It extends into the spruce, and it's worn deeper in the soft summer growth, leaving the harder winter lines standing proud.  What's nice is that the abraded surface is fairly fresh and clean looking.

This is a chip on the lower bout.  This seems to be nitrocellulose lacquer, and it's very thin for a production model guitar. (That's not a bad thing). You can't see it well in these photos, but the entire surface has that sunken washboard effect one finds in nitro that has been buffed soon after spraying. This chip has been exposed to the elements for much longer and the spruce has oxidized quite a bit.

It's a multistage process.   I start with a thin coat of cyanoacrylate to seal the wood surface, followed by light washes of dewaxed shellac tinted with dye in an effort to match the darkened lacquer.  This is a guessing game. The tendency is to go too dark, and one has to remember that the new lacquer is going to age and darken as well.  In the end, I'm happy to subdue the raw white of the abrasion.
Next comes another layer of cyanoacrylate, and finally several coats of lacquer, sanded and leveled prior to hand-rubbing with polishing compound. The lacquer keeps sinking into the canyons between growth lines!

I didn't use any color on the chip, because I had a hunch about the surface oxidation. The longer it's exposed to air the darker it gets.  Have a look at the joists in a the attic of a fifty year old house and marvel at the complex chemical reaction! After a century they're like dark chocolate.   At least this appears cared-for, and it's not prone to further flaking.

 The area next to the bridge fared better.  The lesson being: if your guitar gets a scrape it's easier to disguise if it's tended to sooner rather than later.