Cautionary Tale: CA Glue and Redwood Staining Around the Rosette

Just a heads up from this amateur builder that CA glue and staining by wicking can be a serious problem with redwood tops. This is an issue that has been discussed before and I took all the usual precautions but still got staining. CA staining has not been an issue with me with other woods I've used like mahogany, Sitka spruce and mrytle. I'm posting this because I think this could be a potentially disasterous event for you more serious builders who might be using sinker redwood. It ain't pretty.

The usual precautions were taken including filling the rosette channel with a 1 to 2 shellac cut, 3 coats with an overnight dry before setting the rosette and gluing with CA. On my latest event, the staining was restricted to the upper part of the sound hole covered by the fretboard so I dodged the bullet, but still it was serious and very deep and no amount of sanding would take it out. I live with redwood trees that live all around me and I can say that this wood absorbs water like a straw and it will absorb CA glue the same way if you are not careful. The effect is ugly and nasty.

Some thoughts on how I would avoid this effect:

1: Use a shellac cut of 1 to 0.5 or even straight to fill end grain.
2: Completely shellac fill the rosette channel missing nothing
3: Do not over flood the rosette with CA hoping to fill voids
4: Maybe consider using a more viscous CA prep like the Stew-Mac 20 instead of the 10 I used
5: Use an accelerator ???

Interestingly, I have had no problems when using SM 10 CA glue when gluing bindings on redwood. Only on rosettes.

Just sayin' and by the way finishing does not hide the stain lines and yet nobody has noticed them except me... But you guys would see it in a ukulele second. Anyway, it just ain't acceptable to me and it is extremely permanent. Extreme potential bummerectomy.

I'd add this to your list:

6: Don't use CA glue.

If rosette is wood, use Titebond or similar. If rosette is ABS, celluloid or other plastic, use an acrylic-based glue.

If you use Chucks CA glue pore fill method, all the stains will vanish i think ....Errr! seems logical :anyone:

Timbuck said:

If you use Chucks CA glue pore fill method, all the stains will vanish i think ....Errr! seems logical :anyone:

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Having gone through a similar experience, I tried to eliminate the stain by coating the whole top in thin CA. Never could get an even appearance--things were a little blotchy. Sanded it all down and proceeded with typical finish regimen. Results were not bad, but not first rate, either.

Timbuck said:

If you use Chucks CA glue pore fill method, all the stains will vanish i think ....Errr! seems logical :anyone:

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I wish that were true Ken. A funny thing happens with redwood and Western red cedar. When you first lay down your blob or squiggle of ca glue, no matter how fast you spread it, the original blob will show up as a ghost, leaving it darker than the surrounding area. An application of shellac under the CA will indeed eliminate the problem but you better be sure not to sand through to the wood on that first coat. When using those woods I don't even sand the first coat of CA filler. (BTW, I would never use thin CA on these woods for their propensity to wick up large amounts of glue. Medium is a much better choice). Other cedars, spruces and hardwoods are not afflicted with this problem. I usually avoid redwood primarily because of the problems mentioned with CA glue. (And secondarily because I don't care for the sound in an ukulele.)

As a follow-up, below a picture of a raw rosette I just glued into myrtle about an hour ago using thin CA. No wicking problems at all as I expected, but I still shellaced the surfaces even though I probably didn't have to. Better safe than sorry... A restrained conservative design I think that doesn't compete too much with the myrtle grain.



Now as to using the methyl acetate acrylics (Weldon, etc.), I have not had good luck with this stuff as a plastic to wood glue, although it does work (sorta) with plastic to plastic. I know this stuff has its partisans and they are able to work with it and get good results. I have not had good results.

I've never bothered using shellac with CA glue except for on redwood and WR cedar. I've never had any problems.

The only time I have had a problem with redwood after a couple of shellac coats is if I have made the rosette channel too tight and broken through the shellac layer. I use the unwaxed strait out of the can.

Moore Bettah Ukuleles said:

I've never bothered using shellac with CA glue except for on redwood and WR cedar. I've never had any problems.

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I shellac everything I've ever cut down into which comes from an early fear (paranoia maybe) when I was working with a really fibrous Sitka spruce top. Not only did the shellac prevent any CA wicking, but it also (in my mind at least) helps prevent the dreaded chip out from my router. I'm going to do another spruce top soon and those layers of schellac help cool my fearful mind if nothing else and peace of mind is important in the uke shop. I hate and fear chip-out almost more than anything else. That being said, there was absolutely no danger whatsoever of chip-out on this recent piece of myrtle. The stuff mills like a dream. The shellac was entirely unneeded from both a chip-out and wicking perspective. This is my first time working with it and I love it. A big surprise was how open pored it is like some "real" hardwoods. Now the question is how is it gonna sound. We shall see.

Maybe I'm special but I've never had a problem with CA wicking and staining spruce. I always apply it to my edges before cutting my binding channels when I'm working with spruce.

Some thoughts on how I would avoid this effect:

or use titebond

I've had CA staining problems to, so now I don't use ca on softwoods for rosettes etc.

I have had problems with the CA accelerator causing staining more so then the glue it self