1973 Martin D18 partial refinish

[bunny]

I have a 1973 Marting D18 with the back stripped to the bare wood, I had to fix the previous "repair" done poorly, reglue the broken part and level the back which was all humps and pits.
The rest of the guitar finish is ok for the overall "working horse" condition and I have no intention to refinish it except some small touch ups.
What would be the correct finishing procedure for the back? Pore filling, staining, sealer, nitro lacquer. What stains or pigments should I use?
Thanks!

[MaineGeezer]

Since nobody else has ventured an opinion...

I suspect that unless you refinish the entire guitar, you'll never get the back to match the sides. If you're okay with that, fine, but it will look amateur-ish unless the refinishing gods smile upon you with uncommon benevolence.

As far as what to use....LMI and StewMac have appropriate pore fillers and such. What stain to use? Whatever gets you the closest match to the sides. I don't know enough to recommend anything in particular. If you're planning on nitro lacquer....how are you with a spray gun? A good spray finish is a deceptively difficult thing to do. You see guys spray painting cars, or guitars, or whatever, and it looks easy. It isn't. At least that's my experience. You may be comfortable spray painting. If so, ignore this.

I'm going to do a French polish finish on the guitar I'm building. One reason is that shellac will be easy to remove if I screw it up.

[B. Howard]

A typical finishing process would be;
Sand out at 180-220
Apply sealer & sand out at 320
Apply paste pore filler such as pore-o-pac
apply sealer and sand out at 320
apply 5-10 coats clear nitro, number of coats will depend on wet mils per caot and solids contenet of the lacquer.
level sand & buff.

[bunny]

Thanks, Brian!! That's what I'd like to have for every finishing schedule! :)
Can you tell me what would be the typical Martin staining method for mahogany?

[B. Howard]

While I can't speak specifically for Martin, the typical process used by Gibson was to actually apply the grain filler to the bare wood and it served the purpose of both filling and staining. I prefer a sealer under mine as it makes the filling process a bit easier and limits the risk of finish delaminations. I will apply my stains between the initial sanding and the first coat of sealer. While I haven't used the brand in quite a while, from what I remember Minwax 225-Red Mahogany was a close match to Martin's color on Mahogany.

[ruby@magpage.com]

I read that Martin used walnut colored filler on their bare mahogany, so I tried it and it looks right. I took this shot of 2 guitars together with this one on the left, so the headstock looks angled when it is not:

[tippie53]

yes it is a dark walnut color about the color of a dark brown chocolate