MIMF

I just watch the hundred-part StewMac series on finishing with nitrocellulose in cans. Is there a practical advantage to nitrocellulose or is it just a tradition thing? It looks like a giant, time-consuming hassle.

Left to my own devices, I'd shoot with a gun (I thought it was weird that they had a spray booth but were using rattle cans). I'd also use activated urethane like I was doing on motorcycles.

I could see how the type of paint they were using would make a difference on an acoustic instrument, but on the solid bodies I want to build it's hard to think it would matter.

Side note: when I was a kid I refinished a cheap acoustic with hardware -store urethane and afterward it sounded even worse

Nitro is definitely a tradition thing, but it is also a very easy material to spray and level. The ability to burn into previous coats is an important property. But other finishes are fine if you keep the finish thin. Thick finishes are what kill tone.

SM pushes their rattle cans cause it makes good profit. Spray guns are a better way to apply finish, if you are properly setup.

You think heavy finish on a solid body instrument would have a significant effect on tone? My favorite method with metal was to use rattle cans for the color and then cover it with activated urethane. I'm sure you end up with something thicker than lacquer but it's super durable and requires very little finish work.

Of course it l's incredibly toxic, so there's that.

I don't think a heavy finish will hurt the tone of a solid body. In that situation, the only real downside of a heavy finish is they tend to chip and crack more easily than a thin finish. But if your urethane is working out well, I would be inclined to keep using it. What brand of finish are you using?

One thing that I am thinking more about these days, especially sisnce I'm trying to move away from nitro to waterborne, is that being a repair person in the future ain't gonna be fun! Although I don't do many repairs anymore, for my combined 50 years of building, nitro and a bit of shellac have been pretty much all I needed to do most any repair. Future repair people are going to hate us! Weird glues, finishes, unknown building components, etc. I'm thinking, and I plan to implement this, that builders need to start including a compendium of all the kinds, of material, finishes, next joints, and other new age stuff used in their builds. No guarantees that it will stay with the instrument, but at least gives future builders and repair people a fighting chance!

I can always fall into my usual rant against nitro. It is a health, fire and safety hazard to use, and breaks down inexorably over time, producing toxic and corrosive fumes. Most of the benefits of using it accrue to the factory that has invested in the technology to work with it more or less safely and expeditiously; the consumer gets the down side. For a small builder there are much better finishes: nitro is a snare.

And if you want to know what I really think... ;(

After using nitro on 60+ guitars, I gave Simtec sealer and 2K acrylic urethane a try.
I sprayed 3 coats of Simtec, sanded, and another 3 coats and sanded on Limba.
Two days total and the pores were completely sealed. It was easy to sand and does not shrink back.
3 coats urethane. Two days later wet sanded with 3000 grit and polished.
Looks perfect and a very hard finish.
The urethane flowed out well enough that some areas like the neck did not require wet sanding or polishing.
The products are nasty and require organic face mask and full clothing.
I sprayed outdoors and there were no issues with dust.
Follow the product instructions and be aware of the cure time, clean your gun after every application.
I’m sold on the stuff.