"Your Gut" as a tool

Construction and repair of Classical Guitar and related instruments
Massimo Barbi
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"Your Gut" as a tool

Post by Massimo Barbi » Fri Jun 09, 2017 7:41 pm

Just a few thoughts as I progress...



I've recently realized that if you find yourself saying "I knew that would happen," you have no excuse for the mistake.

I am starting to try to use my "gut" as a tool. It's uncomfortable at first as you can't calibrate or test it, like you could a caliper, without risking failure. But I am learning that it's better to risk that failure than to run your shop without your gut on the bench.
In the process of finishing my second guitar with a French polish, I decided to do some high grit, wet-sand leveling on the top and back today. I
knew I should have laid more shellac on the top first. Though relatively unfamiliar with the process and how many polishing sessions to do (I do realize sanding is not part of true French polishing), I could just tell for whatever reason that the finish on the top was not nearly thick enough. But I had shown the guitar to my boss- not a guitar builder- and he said, "I don't do French polishing, but it looks good to me," so I went against that feeling in my stomach and sanded through the shellac in some spots, wetting the exposed grain with the water from sanding and raising it. It's an unsightly and bumpy texture now.

And the only thing I would have risked was some more time spent polishing before sanding. I see that using your instincts, though risky at first, will build proficiency with them and your making as a whole. I guess it's like figuring out how far you can progress your plane iron, inching it forward until you gouge out a long track of rosewood. Next time you'll know better. After all, I've heard the old makers in Spain used to thickness their plates with their fingers.

Any thoughts on this? Anyone recently said "I should've known," or listened to your gut?

MessyTendon
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Re: "Your Gut" as a tool

Post by MessyTendon » Fri Jun 09, 2017 8:29 pm

Slow and steady wins the race. I am starting my first guitar next week. But I have practiced shellac on many guitars. I got good results on the first one, but I had to undo a bunch of mistakes.

First mistake...I did what you did, sandpaper, loads up with shellac...all that work applying it...gone. The important thing is to allow the actual shellac to harden.

Everybody has different methods. But I think it's important to take the first layer and let it sit for a few days, then do another, and another. Because at times when you take a polishing session, sometime solvent carries some shellac over to the next area while leaving the other thinner.

I think it's important to just polish the hell out of the guitar with lot's of elbow grease. It sounds like it's possible you got some abrasive trapped underneath the shellac causing the roughness. But that's just a guess...I certainly did that a few times.

What I learned...the initial polish, is not perfect or pretty. It gets better with time. At some point, the polish actually looks refined. Then there is a diminishing. When you feel you reached the point of diminishing from the polishing session, I think that's when the final abrasion polish should be done.

I used a mix of things. I think the scratch pattern is what creates the mirror polish, that is the shine you see. You aren't actually creating the polish by sanding, and the more you sand, the more shellac you actually remove. We are talking a very thin finish. So the final abrasion, is merely a visual effect of the scratch patterns. Less is more. But I'm not an expert, just somebody who tried and found it, not hard to get a good looking finish.

Massimo Barbi
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Re: "Your Gut" as a tool

Post by Massimo Barbi » Fri Jun 09, 2017 9:38 pm

Thanks for the reply. I had done three or four polishing sessions after the spit coats with about a week between each. What made me want to sand was that the shellac had shrunk back into the wood grain, creating a fairly glossy but not smooth surface. I sanded in order to level it, with the intention of going back to polishing to build shellac and get that luster back. Unfortunately there wasn't really enough shellac on the top to sand like that. From what I can tell, what created the bumps is where I sanded through the finish on the high part of the spruce annual rings (I don't mind being able to see that lined texture on the spruce, I was trying to get rid of a finer pitted texture), and swelled the newly exposed wood. So I have little streaks of bare summer rings that are shellac-less and raised above the rest of the surface. In fact I think they've now dried out and shrunk below the surface making what looks like little tears or large scratches in the finish. I'm hoping that with more polishing like you recommend they'll naturally get filled and leveled.

Massimo Barbi
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Re: "Your Gut" as a tool

Post by Massimo Barbi » Fri Jun 09, 2017 9:39 pm

Thanks for the tips, especially about the "diminishing". That is helpful.

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Philipp Lerche
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Re: "Your Gut" as a tool

Post by Philipp Lerche » Tue Jun 20, 2017 8:44 pm

This thread put a smile on my face instantly !
My gut is working the same way and I had situations where could slap myself, because I pretty much knew it will go wrong.
But thats part of the whole thing, we train our feeling for materials and tools. Sometimes we just forget to listen to our inner voice.
The question for me is; is it possible to go to far with listening to your gut ?

I mean for example don't measure thickness by a tool and just bend, tap, feel & smell if the guitar top is perfectly done.
For me it is quite a romantic idea, that a luthier can be experienced enough to feel all those things which gives the instrument its unique character.

I'm defo using my gut as a tool right now & its also interesting what others think about it.
"If you spend too much time thinking about a thing, you'll never get it done."
Bruce Lee

Best regards
Phil

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Alexandru Marian
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Re: "Your Gut" as a tool

Post by Alexandru Marian » Tue Jun 20, 2017 9:26 pm

I would not use water to level shellac even if thick and cured. It goes through it very fast. Use olive oil, while for localized sanding the warts that appear sometimes over dust or lint you can go dry too. Discard (or wash) the paper as soon as it accumulates shellac warts.

Dave M
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Re: "Your Gut" as a tool

Post by Dave M » Tue Jun 20, 2017 9:59 pm

Yes that feeling is so familiar!

I would put it slightly differently however. I think for we amateurs (and please excuse the term if that is not the case), we are trying to develop craftsmanship which the more professional among us have spent a lot of time acquiring, along with some proper training. So I think that little voice is actually the beginnings of a developing skill and we need to recognise it as such, pause and say hang on don't I remember reading, hearing, noticing that particular action is not going to work!

As someone coming to this craft at a certain age I find I really have to keep the focus levels high to avoid those mistakes which perhaps a better trained and experienced builder might not have to think about so much.

But it does get better the more you do it. By listening to that little voice befoe rushing ahead the quality of work does get better.(well most of the time!)
Dave

Francisco
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Re: "Your Gut" as a tool

Post by Francisco » Tue Jun 20, 2017 11:10 pm

Massimo Barbi wrote:
Fri Jun 09, 2017 7:41 pm
After all, I've heard the old makers in Spain used to thickness their plates with their fingers.
https://en.wikipedia.org/wiki/Antonio_de_Torres_Jurado
During his later years, Torres' close friend, a priest named Juan Martínez Sirvent, lent him a hand in his workshop. Many years later, in 1931 Sirvent wrote a letter to Francisco Rodríguez Torres, mentioning the following explanation Torres made when he, at the age of 68 was asked by the famous father Garzón at a dinner about his "secret" of how to make his outstandingly sounding guitars:[5]

"[...] smilingly [Torres] responded: 'Father, I am very sorry that a man like you also falls victim of that idea that runs among ignorant people, Juanito (that is how he addressed me) has been witness to the secret many times, but it is impossible for me to leave the secret behind for posterity; this will go to the tomb with me for it is the result of the feel of the tips of the thumb and forefinger communicating to my intellect whether the soundboard is properly worked out to correspond with the guitar maker's concept and the sound required of the instrument'.
Yamaha GC42S

Massimo Barbi
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Re: "Your Gut" as a tool

Post by Massimo Barbi » Thu Jul 13, 2017 12:51 am

Glad to have the confirmation from Torres himself! And glad I'm not the only one who feels this way.

Alexandru Marian - thanks for the reply and advice. I was following the process of a luthier's (can't think of who at the moment) tutorial on YouTube. He actually warned against oil because he said it would clog the paper. After my experience I would rather go through paper like you said than through my finish!

Douglass Scott
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Re: "Your Gut" as a tool

Post by Douglass Scott » Thu Jul 13, 2017 3:35 pm

There's no perfect way to sand French polish. If you haven't oiled your guitar before beginning to French polish and then use oil to lubricate the sandpaper, the oil will soak into the wood in any spots where you sand through making that spot permanently look really different from everywhere else. Some think naphtha is good because it lubricates and also evaporates completely. I use the sandpaper dry but you need to be very careful not to scratch.

Douglass Scott
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Re: "Your Gut" as a tool

Post by Douglass Scott » Thu Jul 13, 2017 3:54 pm

Like Dave said I think that voice means you're learning something. You didn't know something was going to go wrong until it actually did - you just had a feeling it might.

In my experience you need to make every possible mistake at least once. Then you know where the lines are that you don't want to cross, and you'll be more sure to listen to that voice. You'll never stop making mistakes, but gradually they won't upset you so much. Early on I discovered making two guitars at once helped get over the burn of a screw up. When I made a mistake on one, I'd be more careful and redeem myself on the other.

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