Old reddish / pink glue? (NMC)

[Drew Streip]

My neighbor picked up an older Giannini Craviola steel string flattop for cheap and brought it to me to fix up and make playable. It appears to have suffered from some "hot car syndrome" -- the bridge is substantially lifting, the pickguard is lifting a bit, there's some belly, and the fretboard is heavily pitted. I'm a little worried about neck angle, but it'll be better with the bridge in the proper position.

My REAL question is, the glue visible under both the bridge and pickguard seems to have a reddish/pink tint. Any ideas what this might be?

At any rate, I plan to remove it all and use double-stick tape for the guard + hide glue for bridge. It's a nice bridge, and the back/sides are highly figured (laminate).

[bpatrick]

Maybe resorcinol glue? Years ago, I glued together some exterior white oak benches with resorcinol glue. It's a two part glue that is reddish-brown. It is described as a precursor to epoxy glues. https://en.wikipedia.org/wiki/Resorcinol_glue

[Richard500]

Drew, I know not that much about this instrument, but I do know the bridge is not supposed to be glued down at all on mandolins. I’m guessing that what you’re seeing at both places is the finish/stain getting soft and transferring. The color could be from that. I’m also guessing that if excessive heat was the problem, and the thing is old enough to have proper hide glue everywhere, that you should tap the top and back to see if there’s a loose seam, and check the neck joint for movement once you add some tension. Somebody with experience could also check the other important dimensional issues especially string height, neck warp and perhaps loose internal bits.

[Drew Streip]

Drew, I know not that much about this instrument, but I do know the bridge is not supposed to be glued down at all on mandolins. I’m guessing that what you’re seeing at both places is the finish/stain getting soft and transferring. The color could be from that. I’m also guessing that if excessive heat was the problem, and the thing is old enough to have proper hide glue everywhere, that you should tap the top and back to see if there’s a loose seam, and check the neck joint for movement once you add some tension. Somebody with experience could also check the other important dimensional issues especially string height, neck warp and perhaps loose internal bits.

Richard, it’s not a mandolin but a flattop steel string guitar.

[Richard500]

Oops!

[Timbofood]

Richard, we all do that from time to time!

[Timbofood]

After thinking about the resorcinol glue thing and coloration or, discoloration. Way back when I was working at the music store (75-78) there seemed to be a batch of “seconds” floating around here from Gibson that clearly illustrated the bracing with “reddish/brownish”staining through the tops. A high school buddy had a “Dove” with the bracing pattern clearly visible.
Don’t know if that helps the price of cocoa in Denver or anything else.

[billhay4]

The resorcinol I used back in the day to make canoe paddles was pretty much pure brown after it cured. No pink or reddish tint.
Bill

[bpatrick]

It would be weirder than resorcinol, but polyester resin used for fiberglass work is pinkish.