Removed top finish. Thinning the top or not?
 

EDIT: For those of you that don't read the whole thread, I have already done the work and I describe the result in a post on page 2. Thanks

I bought a used Recording King RO126. I was surprised how good it is for the price paid, and even without considering the price. So good that I think it can be... even better. I would like to expand the dynamic range.
I took it to my luthier with the idea of reducing the bracing to let the top move a little more. He told me that braces are good and scalloped enough and that the "problem" is that very thick polyester finish. "Remove it and then we do a nitro finishing so the top will move like you want".
So I removed the bridge. Since the bridge was too heavy we removed wood mass from the bridge itself to let the trebles ring a little more (they were softer than the basses).
Then I removed all the finishing from the top and I was thinking of making the top thinner than it is, so it can move more and more.
The luthier told me that it is not a good idea because the sound can lose some "body" (if this has a sense translated in english)
I am confused, I always thought that a lighter top can produce a louder sound with more dynamic...
I imagine that a guitar like this is overly built to resist everything. It is short scale (24.9) and I will put only light strings (12-53) so in my opinion it could be much lighter than it is. A lot.
Maybe the sound could be good enough right now, but before re-glueing the bridge and discover it (and maybe take it off once again) I would like to have some skilled luthier opinion.
How thin can be the top? Do I remove mass or not? If yes do I remove mass even under the bridge or only around it?
Thanks everyone for your precious help

Wood costs money. I'm no luthier, but in going to guess they didn't use a lot more than they need to.

The top is just one of many influencers of tone. Thinning it will change the overall dynamics, but in what way, and whether it is pleasing or not, is a total experiment.

Go too far, and you will not realize the damage you have done to structural integrity until it is restrung and under tension for a while.

The likely result is warping of the top, bellying behind the bridge, and perhaps broken or unglued braces, as they are called upon to do too much of the work.

Unless it is a guitar you can risk throwing away, I would not mess with the top thickness, especially if you removed the poly finish by sanding.

You are well on the way to having a ruined guitar. Might as well complete the destruction and just sand down the top so it explodes under tension.

With the absolute plethora of used acoustic guitars flooding the market at all price points, I think you can likely find the tone you are looking for without having to fire up the belt sander.

I have never heard of taking mass out of a top - removing the thick finish as you have already done is likely going to impact the tone more than any additional wood removal will accomplish. I'm no luthier, but I would question the competency of any luthier that suggested you proceed with this course of action.

Think in terms of stiffness, rather than mass. Reducing the thickness lowers the stiffness more quickly than mass, so you can end up with a flabby guitar that is likely to have excess belly. It may be louder, but tone quality and sustain will probably suffer. The more you head in this direction, the more it will sound like a banjo.

Once you remove the wood it's a done deal.😬😰

OK, thank you so much for your suggestions.
So it seems like I stop my work and I re-glue the bridge and see what happens.
To be honest I'm not so much afraid of the work done. Hey, it is a cheap guitar and it is the right one to do some experiments. I will never do that on an expensive and quality guitar.
To be honest I am expecting an overall improvement, if it is not so it is not a big problem.
Thank you once again for your support and ideas.

There's missing information:

Did you remove wood when removing the finish?
What is the current top thickness (that you judge to be too thick)?
What is top material; sitka?

I was very careful. I'm sure I didn't remove any wood.
The top is Sitka.
I am not sure of the current thickness. I can measure it only on the sound hole that is 2.96 mm (0.12 inch) but I am not sure if it is the same on all the soundboard.
I have to go to the luthier to take the right measure, he can do that.
I will do it in a few days.

It sounds like your luthier gave you good advice - remove the thick finish on the top and then apply a thinner finish and be content with that. If you liked the sound of the guitar to begin with, a thinner finish on the top _may_ give you a little more, but changing things in a big way (sanding the top) will most likely give you less. For some reason people seem to think the lighter a guitar is the better it will sound, which is not true. And a too thin top makes the instrument sound "thin".
If you want to play around with sanding a top find a cheap instrument that you think sounds bad. It is better to go from bad to worse than it is to go from good to bad.:D

Your logic is faulty.

If something is “so good” as it is, what makes you think it can be better? How do you know that it isn’t already the best it can be, already fully optimized for what you want and that any change to it will make it worse?

I wish it really was as simple a path to the best tone as just changing the finish and reducing mass. if it were, every instrument would be great, since the formula would be so easy to implement and achieve.

Unless you have experience with doing this , i suggest you dont do it.
many changes like this are impossible to come back from .
if your not happy with the results .

Of course , its your instrument you can do what ever you want to with it
but you dont want to say " should off, could of "

The finish makes good sense. The thinning top, I would hesitate personally.

Ed

Hi Eso612,

If you sanded all the old finish off the top, you have already removed at least a little of the top thickness. That probably will help. It helped on my Santa Cruz OM/PW when the top was refinished due to some blue staining of the top because of bleeding from the case inner material. When I got my OM/PW back from Santa Cruz it had more treble. For me, it was a better sounding guitar. Maybe reducing top thickness had nothing to do with more treble -- maybe the finish was a little thinner, who knows. Santa Cruz did not care to speculate at all about why the change in sound occurred. It was fairly subtle, anyway.

As others have suggested, it's probably best not to remove any more top material.

- Glenn