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I am getting here and there something that appears to be spruce endgrain contamination from the fish glue i use. It happens with the rosette and the purfling. It is not a problem if I do not need to sand the piece too much, especially with the frnech polish on the coloring is very hardly visible even if knowing what to look for, but if I need to take off some thickness, the color problem turns into a mechanical problem towards the center of the piece: can even run into sort of void pockets, even worse than the pictures below...(click to zoom in)

It sort of looks like routing tearout filled with glue/dust, but no, the channel was perfectly and smoothly cut with a gramil.

Strange that I did not notice the problem on my first 3 guitars. The 4th has had some of this issue, and now thinning the top of my 5th and there it is again at the rosette.

I believe it happens because the fish glue has a very long open time, so it has plenty of time to soak in, perhaps moving some color from the hardwood too.

It is obvious that in the future I need to seal the rosette and purfling channel walls with either hide glue or shellac. Wonder which would be better?

So this thread is also sort of a warning for those that plan to try fish without sealing first.

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Build log

One thing to consider is that color may be bleeding out of your rosette strips if you work too "wet" (i.e. wiping off excess glue with a wet rag etc.). Your purfling material looks to be dyed rather than natural and this is more prone to color bleed.
Natural colors might be a better choice and certainly a light shellac seal to the channel prior to glueing would help.

Also has this completely dried? Or are you leveling it soon after the installation? I've found that glue residue (of any type) if still soft will resist being cut by the paper and will remain right at the juncture of the outermost ring and spruce edge and won't sand away till its bone dry.

I've been using fish glue for rosettes and purfling installation as well and have not gotten this effect with natural veneers. Though it has happened with dyed ones.

Yes dry as a bone. The red is bloodwood, although I do not think being natural helps anything here. A bit of alcohol yields lots of red out of it. But it also happened with Indian rosewood purfling on my latest finished guitar.

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Build log

Hi Alex, I agree with David about the bleeding issue and I know that bloodwood will bleed ( ) easily as well. On your channel, I respectfully suggest that your gramil is crushing some of the end grain. Spruce is very fragile in that area because the long tenacious just does not want to separate from itself and will tear rather than cut fairly easily. So there is probably a combination of things going on, the long open time of the glue likely does allow for some migration into the exposed ends of the endgrain cells (fix this by sealing the channel with shellac) and I suggest that there is a bit of fibre damage occurring during gramilling (is that a word?). This can be fixed by ensuring your gramil is VERY sharp and reducing pressure, allowing the fibres to be entirely sliced.

Good luck

Shane

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Canada

I was going to suggest the same thing as Shane pointed to. Even though it may not be tearing wood out, it does look as though fibers are being dragged and crushed. A sharp cutter and light pressure are key in avoiding this, and even though it may not tear out chips, a dull cutter can certainly crush fibers which will absorb glues (and whatever pigments they may carry) just like this.

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Eschew obfuscation, espouse elucidation.

Thank everyone for the replies! I'll try to keep it sharper and go slower. I'm still not the most patient builder in the bunch...

Regarding sizing, shellac is easy to add, but will it not inhibit the adhesion between spruce and purfling? I was thinking a runnier hide glue would be better. It should seal the fibers without soaking in (cause it gels fast), and the additional fish or hide whatever I use will bond perfectly to it.

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Build log

Excellent tips from Shane and David Collins!
Just for the record, E.I. rosewood is THE worst for bleeding of the natural colors (I should have singled it out in my initial post).
I usually use Brazilian rosewood at the spruce edge which is much better.

Don't forget the cocobolo.

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Howard Klepper
http://www.klepperguitars.com

When all else fails, clean the shop.