Cloth reinforced top

brent635 · #1 03-10-2021, 07:41 PM

I'll be removing the bottom from my H2145 archtop to fix some internal issues. The top is lined with cloth, I assume to reinforce the f-holes. Does the cloth dampen the sound much? Would it be better to remove it and reinforce the f-holes with wood veneer instead?

charles Tauber · #2 03-10-2021, 08:10 PM

Quote:

Originally Posted by brent635

The top is lined with cloth, I assume to reinforce the f-holes.

I've not seen that done before.

Quote:

Would it be better to remove it and reinforce the f-holes with wood veneer instead?

F-holes aren't usually reinforced.

redir · #3 03-10-2021, 09:07 PM

I have seen that before. Just a piece of cloth glued to the f-hole in what looks like an attempt to sure it up a bit. I don't think you mean that the entire top was covered in cloth right? I can't remember what guitar it was I saw that on now. But it was basically a rectangular cloth patch and it looked like it was glued in place first and then cut through but I'm not sure.

I have also seen wood veneer for the same purpose which imo would be a better way to sure up the f-hole.

I would just leave it. It was part of the original design for one thing and also I doubt it would have any impact on tone.

brent635 · #4 03-11-2021, 06:56 AM

Quote:

Originally Posted by redir

I have seen that before. Just a piece of cloth glued to the f-hole in what looks like an attempt to sure it up a bit. I don't think you mean that the entire top was covered in cloth right?

Using a dental mirror, the cloth appears to cover the whole middle of the top, not just around the f-holes. That's why I wondered about tone. It's like this one:

Rudy4 · #5 03-11-2021, 08:04 AM

Good question to ponder.

In the era of all those inexpensive archtops being produced I'd venture that tone wasn't a primary concern. Preventing top cracks on solid top instruments was probably more of a motivation, so if a little gauze was a good thing, why not more?

The only vintage arch top I've owned was a 39 Epiphone Triumph with a carved spruce top. It felt smooth inside the f holes and I didn't have cause to look inside.

The cloth tape is often seen in strips added to guitar sides as insurance towards cracks not developing. I've seen it as patches around f holes, but not that much.

The 2 carved top instruments with f holes that I've made I used thin (.040") veneer about a 1/2" bigger than the f holes and applied 90 degrees to the grain direction. I beveled the bottom edge back slightly at the f hole edges so it couldn't be seen and didn't make the top look thicker than it was.

redir · #6 03-11-2021, 08:26 AM

Yeah that's a lot of cloth. I would be concerned about that on a solid arched top and not so much on a laminate.

John Arnold · #7 03-11-2021, 08:54 AM

It is a pressed top, hence the excess reinforcement.

Alan Carruth · #8 03-11-2021, 09:10 AM

I ran a test once of the reinforcing effect of cloth side tapes. I made up standard wood samples with and without various tapes and glues, and tested them to see how much force it took to break them. The tapes were quite effective; it took about 50% more force to break any sample with a tape than without. There were some differences depending on the type of tape and the glue. In use I've found that side tapes do a pretty good job of limiting the spread of side cracks: they tend to run up to the next tape and stop, rather than going the whole length of the side.

One big issue with all such reinforcements is that air gets at the glue and breaks it down over time. They used to glue paper on the inside of mandolin bowls to reinforce the joints, and when you open them up the paper is often flapping loose. Not much help there. I've been shellacking my side tapes after putting them on, building up enough to get a bit of a shine, in the hope that will help the glue to last longer. We'll find out in 75 years or so. If I were working on that guitar I'd shellac the cloth patch while I had it open. It probably couldn't hurt.

I don't have any data on the effects of the cloth on either stiffness or damping. I would expect that the cross grain stiffness, at least, and the damping both rise.

brent635 · #9 03-11-2021, 06:51 PM

Quote:

Originally Posted by John Arnold

It is a pressed top, hence the excess reinforcement.

Interesting point! I see a lot of old pressed tops will crack badly, but this one is perfect. I guess the cloth is doing its job.

brent635 · #10 03-11-2021, 08:07 PM

Quote:

Originally Posted by Alan Carruth

If I were working on that guitar I'd shellac the cloth patch while I had it open. It probably couldn't hurt.

I'll give it a try and let you know.

ArchtopLover · #11 03-12-2021, 07:35 PM

All of the archtops, that I have repaired to date, use some form of reinforcement for the F holes. This is either, thin wood veneers, cotton muslin, cotton gauze or in some cases I've seen news paper glued over the F hole cut-outs.

This technique is the traditional method of reinforcement and should be respected as such. The idea is simple, cracks are going to happen in solid wood tops, this can not be prevented only mitigated. Since the f hole represents the beginning of a crack in the top to begin with, adding the cloth reinforcement acts like rip-stop nylon, the fabric stops a crack from spreading.

Yes, it looks like this factory used a little too much, that's OK. It will not effect the tone, since it is so light weight. Removing it and replacing it with wood veneer will add mass and will likely change the tone, since the wood veneer must be positioned perpendicular to the grain of the top, just like a ply-wood/laminate, in order to achieve the same "crack stopping" performance of cotton gauze.

printer2 · #12 03-13-2021, 01:10 PM

Quote:

Originally Posted by ArchtopLover

All of the archtops, that I have repaired to date, use some form of reinforcement for the F holes.

So the reinforcement caused repairs to be needed?

Just kidding.

brent635 · #13 03-14-2021, 05:09 AM

Quote:

Originally Posted by ArchtopLover

Yes, it looks like this factory used a little too much, that's OK. It will not effect the tone, since it is so light weight.

Thanks for the reassurance. I don't know how I would have removed it anyway LOL.

brent635 · #14 05-11-2021, 09:32 AM

Quote:

Originally Posted by brent635

Thanks for the reassurance. I don't know how I would have removed it anyway LOL.

Update: When I got the back off, the cloth was more like canvas than gauze and it was everywhere. Since I figured it was probably glued down with hide glue, I laid alcohol on it. The glue weakened to some extent and I was able to strip it off.

Then I put in chips of wood veneer to reinforce. Now it sounds like wood instead of a blanket.

ArchtopLover · #15 05-11-2021, 01:39 PM

Now that I see the extent of the cloth application to the sound board top plates I can agree and say that this was not just simple F hole "reinforcement"; the builder got seriously carried away and just smothered the whole thing in a bandage. So, yeah, it had to be removed.

It would be interesting to have heard this archtop recorded in a before and after session, just to hear how much the tone was affected.