Official Luthiers Forum!

I'm finally to the point where I can being prepping my first acoustic build for the finishing process.
I have a few noob questions that I am hoping I can get some of you guys to answer for me.

I've listed what I believe will be my steps to prep the wood, but I have a few questions in bold that I'm still not clear on...
Does the below order and process sound correct?

1)Sand entire body to 220...Black Limba back and sides, sitka spruce soundboard, mahogany neck, and black binding.

a. Can I just sand over the binding also?

2) Sanding Sealer on Neck, Back and Sides

a. I assume tape of my bridge spot here?
b. Do I sanding seal my Sitka Soundboard too?
c. Do I sanding seal over my binding?

3) Pore Fill on Neck, Back and Sides

a. Do I need to tape over my binding while grain filling?

4) Sand entire body again to 220
5) Begin finish (Nitro or French polish TBD)

Thanks!

Yes, you can and should sand over the binding. After you apply a couple of coats of sealer you will not need to mask the binding during grain filling. Sealer can be applied to top and binding. Masking the footprint of the bridge is optional.

When you say sanding sealer, exactly what product are you talking about? I use vinyl sealer under my lacquer finishes.

Sand to 320, then 400.

Do you sand all the way to 400 before you apply finish? That's impressive, I tend to stop at 220.

sometimes it is a good idea to raise the grain as you finish sanding so your applied coating won't raise the grain when you apply it. Wipe your guitar and neck with a watered damp cloth (just the parts that will get finish) let it dry and then do your 220, or whatever your finishing grit is, sanding.

I sand to 220 except if I am using plastic binding it gets sanded to 320. Also curly maple likes 320 grit.

Ebony and rosewood fretboards get sanded up to 600 grit and then buffed.

I’d recommend sanding past 220. ESPECIALLY if you’re going to FP.

Also make sure your pore fill of choice will play nice with the finish you plan on using. Once you figure out what exact products you’ll be using post here and I’m sure folks can tell you.

Congrats on getting close! Good luck on finishing !


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A poster on the wall of the Martin finishing shop - I got it off another forum perhaps 5 years ago

Ed

https://www.flickr.com/photos/ruby1638/48921804176/in/dateposted-public/

I sand the neck and body to 320. Be sure to sand all end grain well, (the neck heel, on the sides of the head stock or where ever you find it). 220 works for the top.

I treat wood binding the same. I also like to round over the edge of the binding during this stage. It gives a more finished feel to the guitar. I have never used a material other than wood for the binding so if that is the case I have no recommendation, but I'm sure others will.

As far as sealing goes, if you plan to use nitro then seal with a manufacture recommended vinyl sealer. but not until you are ready to apply the nitro. For french polish, I would again seal with the finish manufacturer recommended sealer but only when the procedure you are using calls for it. I consider, pore fill, sealer and finish material all part of the finish process.

There are times when you need to seal this or that part of the guitar during construction, but it will be sanded to bare wood when you start the finishing process.

If you are plannng to fill the pores be sure you have filler, sealer, and finish that all work together. It is best to follow recommendations for the particular products you have chosen. For instance, I usually use an epoxy filler direct on bare wood. After the epoxy has cured 3 or more days depending on conditions, then you can start the finishing. For nitro I use vinyl sealer first, over the epoxy, followed within thirty minutes by the first coat of nitro. I use Cardinal and that is their recommendation.

_________________
Joe Beaver
Maker of Sawdust

I don't think anyone's mentioned to test the finishing schedule on something besides the guitar... I think experimenting on the instrument itself is a very sporty proposition.

_________________
Peter Havriluk

Both professional finishers that I worked with told me back in the day that 220 - 240 grit was what I sand too, anything finer was not recommended. This is for nitro, cat poly and cat urethane. Other finishes such as varnishes which I never used may be different as Vic said.

Thanks so much for the replies everyone. Maybe one day I'll get to finish this darn thing!