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top bracing


j45nick

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I didn't intend to hijack Avery's excellent thread on his Tim Hardin cover, but I noticed something unusual in the picture of his 1968 J-50.

 

The position of every top brace telegraphs perfectly through the top. You can even see the top kerfing and the bridgeplate.

 

Has anyone seen this before, at least to this degree? I think I have seen this effect replicated using a strong light on the inside of the guitar, but I've never seen it quite like this.

 

Not sure if the link I copied from his thread will work of not.

 

IMG_1026_zps0s3lw6nd.jpg

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Guitars built with Phenol Formaldehyde "radio glue" exhibit this phenomenon. Gibson used it in the seventies, for sure, but apparently even earlier.

 

In "Gibson's Fabulous Flattops," it's described as a quick drying glue that reacted to a radio frequency that was directed through it to speed up the drying time. "A visible side effect was a 'burned" look...It's not uncommon to see..the entire pattern of braces...visible from the outside..."

 

Red 333

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Remind me to never play poker with you, Nick.

 

Excellent observational skills. I did notice there was something different, a more brown effect to the finish that had me wondering if it had been sanded, which would result in a slightly thinner top, and re-fin'ed, but . . . can anyone think of why this would be like this? Sound, and air does move through more than just the soundhole, and could the darkening of the top happen more in the areas that weren't covered by braces? And; is that an oversize bridge plate showing, as well?

 

Bizarre.

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Remind me to never play poker with you.

 

Excellent observational skills. I did notice there was something different, a more brown effect to the finish that had me wondering if it had been sanded, which would result in a slightly thinner top, and re-fin'ed, but . . . can anyone think of why this would be like this? Sound, and air does move through more than just the soundhole, and could the darkening of the top happen more in the areas that weren't covered by braces? And; is that an oversize bridge plate showing, as well?

 

Bizarre.

 

See my post above yours.

 

Red 333

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Guitars built with Phenol Formaldehyde "radio glue" exhibit this phenomenon. Gibson used it in the seventies, for sure, but apparently even earlier.

 

In "Gibson's Fabulous Flattops," it's described as a quick drying glue that reacted to a radio frequency that was directed through it to speed up the drying time. "A visible side effect was a 'burned" look...It's not uncommon to see..the entire pattern of braces...visible from the outside..."

 

Red 333

 

 

Interesting. My 1948-'50 J-45 was re-topped by Gibson in 1968, and I stripped the 1968 cherryburst off a couple of years later, re-spraying with clear nitro, so that it lived life as a J-50 until 2010. There was no evidence of this type of print-through, but they may have used different glue in the repair shop compared to the assembly line.

 

Gibson was really churning out the guitars about that time.

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I've seen the effect a few times, but not before production from the late 1968 era. So my surmise is that it began around then and continued more frequently during the 1970's. It was supposed to facilitate rapid assembly which - to my knowledge - worked OK. The problem was that it also weakened the tops and resulted in plenty of warranty returns and a considerable amount of bad reaction from customers.

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Very good info, Red; your electric guitar-ness is showing. There is an old thread on the Les Paul forum talking about this, and "Uncle Gary", reply #3, recalls something from Fabulous Flat-Tops:

 

"IIRC, the book "Gibson's Fabulous Flat Top Guitars", co-written by Dan Erlewine, mentions some kind of glue cured by radio waves. I remember reading that it was used for gluing braces on acoustics in the early '70's. Apparently, if the glue was "overcured", it would burn, and the bracing pattern would show up right through the spruce top after the guitar was a few years old. The Hummingbird shown on page 116 shows this. I'd always thought that this was a Norlin "innovation". I didn't know it extended back to the 50's"

 

http://www.lespaulforum.com/forum/showthread.php?133296-Radio-glue

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My repair guy once told me Gibson only used radio glue for a short time, discontinuing its use because it was a dark glue and after a few mon5ths the braces started showing through the spruce tops. Like others here, however, I had always associated that glue with the 1970s.

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Interesting. So much that i've tried to gather some pictures and found that one :

http://www.guitar-museum.com/guitar-39937-Gibson-J-50-D-J50-deluxe-J-45-acoustic-guitar-70-s

 

Not same pattern but we can clearly see the bracings as well.

 

 

That is the notorious Gibson double-X brace pattern in that picture. You just look at it and say "what were they thinking?" It is absolutely guaranteed to reduce top vibrations, which is why Gibsons from this period frequently sound like they are "stuffed full of socks."

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Frequently! Once in a while you fall across an example that somehow manages to rise above its disadvantages, but not often. Norlin liked the 'radio glue' notion for a while though, bless 'em. The absolute worst of the lot got peddled to Kalamazoo area music stores around the holidays with BGN stamped on the back of the headstock. We used to refer to the 'bargain' designation as 'Buyer Got Nailed'.

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Frequently! Once in a while you fall across an example that somehow manages to rise above its disadvantages, but not often. Norlin liked the 'radio glue' notion for a while though, bless 'em. The absolute worst of the lot got peddled to Kalamazoo area music stores around the holidays with BGN stamped on the back of the headstock. We used to refer to the 'bargain' designation as 'Buyer Got Nailed'.

 

 

I was being kind using the term "frequently." There are good ones out there from this period, but they are the exception rather than the rule.

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I didn't intend to hijack Avery's excellent thread on his Tim Hardin cover, but I noticed something unusual in the picture of his 1968 J-50.

 

The position of every top brace telegraphs perfectly through the top. You can even see the top kerfing and the bridgeplate.

 

Has anyone seen this before, at least to this degree? I think I have seen this effect replicated using a strong light on the inside of the guitar, but I've never seen it quite like this.

 

Not sure if the link I copied from his thread will work of not.

 

IMG_1026_zps0s3lw6nd.jpg

 

 

 

 

 

Very low humidity (10%) will cause things like that, I read, and I have looked for the 'humidity damage list' I was reading recently and cannot find it anywhere - a sliding scale of humidity effects on acoustic guitars 10% -100%...

 

 

 

BluesKing777.

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I was being kind using the term "frequently." There are good ones out there from this period, but they are the exception rather than the rule.

Exactly - perhaps more the exception that proves the rule?

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Very low humidity (10%) will cause things like that, I read, and I have looked for the 'humidity damage list' I was reading recently and cannot find it anywhere - a sliding scale of humidity effects on acoustic guitars 10% -100%...

 

 

 

BluesKing777.

Hope you manage to find it. That would be fine information to have!

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That is the notorious Gibson double-X brace pattern in that picture. You just look at it and say "what were they thinking?" It is absolutely guaranteed to reduce top vibrations, which is why Gibsons from this period frequently sound like they are "stuffed full of socks."

That is not the double x to my eye. I only see one x. The double x was just that, another x below the first and the center diamond filled in by bridge plate.

http://www.burkettguitars.com/70dblx.jpg

Oddly the radio glue ones I have seen the braces appear darker through the top not lighter.

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Guitars built with Phenol Formaldehyde "radio glue" exhibit this phenomenon. Gibson used it in the seventies, for sure, but apparently even earlier.

 

In "Gibson's Fabulous Flattops," it's described as a quick drying glue that reacted to a radio frequency that was directed through it to speed up the drying time. "A visible side effect was a 'burned" look...It's not uncommon to see..the entire pattern of braces...visible from the outside..."

 

Red 333

 

great post Red...

 

I never would have sorted that one out.

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That is not the double x to my eye. I only see one x. The double x was just that, another x below the first and the center diamond filled in by bridge plate.

http://www.burkettgu....com/70dblx.jpg

Oddly the radio glue ones I have seen the braces appear darker through the top not lighter.

It seems the 1970's J-50 Deluxe is darkened on each side of the braces, not above the wooden sticks. This mystifies the impression of the pattern we see.

It could look like a double-double X-bracing - but probably is the standard Norlin version, which is like the Jumbo in your photo.

 

 

Wow ! What a perspective behavior art work ! I would play it more seriously with such a perspective image in mind !

Hep for the new avatar picture ^ grading up there as well.

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And here's another pattern I never knew.

Quite tempting to press the button and send the good luthier into custom-land. Yes, he could remove the 2 extra X-legs and go from there.

Might turn out to be one special, , , , ½ Gibson.

http://www.ebay.com/...%3D182470261458

 

 

Interesting. Maybe an early iteration of the double-X concept?

 

Look at the size of the bridgeplate!

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Very interesting. Now that I look at Mafy pic it looks like a combination of this one and the one I posted. A double x, double x if you will. I see shadows of double x above and below the bridge plate (on Mafy).

 

Edit: Second or third look looks like single double x. Assuming the radio frequency glue darkens the braces.

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