How does one improve on the durability of a shellac french polish finish?

[Srick]

Way back in college chemistry I was taught you could not easily create 200 proof alcohol because of water in the atmosphere. And regardless, grain alcohol works just fine. A little goes a long way. I prefer the grain because it’s pure ethanol - no methanol, which is toxic, and no denaturants of unknown stripe. Of course grain alcohol is toxic too, but your body can metabolize it to an extent <lol!>.

I get my flakes from shellac.net and it’s pretty easy to whip up a batch. This is what I use for finishing. For a quick blast of shellac, sometimes I will spray some Zinnser Bullseye into a cup and use that. It’s always fresh, but it does have a shelf life.

Just today, I may have shortened the French polishing protocol by days. I porefilled mahogany with GluBoost and then, after scraping, I sanded the surface with Assilex and bufflex sheets. At that point, just a few coats of shellac have provided a wonderful gloss, plus it’s already flattened and mirror like. Almost too good to be true. I’ll keep the forum posted on this.

And back to your original question, there are resins that can be added to the shellac to increase its hardness, but there’s not a lot of detailed information out there. Simply letting the shellac age on a surface increases its hardness and durability over time.

[beginner]

thank you....i just went too fast, beginners mistake....at some point it looked so pretty and i had hoped that more was better

looking forward to seeing how your technique worked out

[phavriluk]

I always thought (and still think) I was blessed by magic when I watched that lumber turn into music. Every time.

[jread]

I always thought (and still think) I was blessed by magic when I watched that lumber turn into music. Every time.

I agree. There's something really cool about those moments when your project goes from carpentry to musical instruments. My biggest charge will always be seeing and hearing talented players make music with these things I built.

[MaineGeezer]

Way back in college chemistry I was taught you could not easily create 200 proof alcohol because of water in the atmosphere.

I knew it was not easy, although I had assumed it was because some amount of water (5%) got carried over in the distillation process. I didn't realize humidity played a significant role.

It is possible to buy 100% alcohol, but I expect one would have to keep it tightly capped and use it quickly before it absorbed moisture from the air.

[Srick]

Way back in college chemistry I was taught you could not easily create 200 proof alcohol because of water in the atmosphere.

I knew it was not easy, although I had assumed it was because some amount of water (5%) got carried over in the distillation process. I didn't realize humidity played a significant role.

It is possible to buy 100% alcohol, but I expect one would have to keep it tightly capped and use it quickly before it absorbed moisture from the air.

You’d probably have to add an anhydrous scavenger to the liquid to remove any water. Way too complicated! 190 proof Grain alcohol works just fine.

I just remembered that Sandarac is the additive used to make traditional shellac harder. It’s a whole ’nother rabbit hole to follow down, just like so much of luthiery.

[MaineGeezer]

Years ago shellac and wax was a common finish for hardwood floors. While certainly inferior to mode modern finishes, it must have had sufficient durability to be chosen for that application. Seems as though a guitar should be less demanding than a floor.

[Tomcat]

Seems as though a guitar should be less demanding than a floor.

Unless you're playing bluegrass...

[beginner]

the shellac french polish finish in my opinion sure looks gorgeous. That said if and when i ever finish this one....I think my next build will use either one of the UV cured options or a light coat of hardwax oil. it would be interesting to see if i can identify a notable difference in acoustic quality.