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Dec 3, 2022 - 5:23:45 AM
3221 posts since 2/18/2009

I just had to do some inlay in rosewood and ran into a problem I have encountered before. I don't do a lot of inlay installation, but when I do it's mostly in ebony. I mix ebony dust and Stew-Mac 30 thick CA glue and use that to fill in around the inlay. It usually gives a few minutes before the glue sets up, which is plenty of time. When I mix rosewood dust with the same glue it sets up rock hard within 5 seconds or so. I don't even have time to finish mixing it before it's gone off. When I put a drop of glue in the bottom of a hole to hold a dot it doesn't do this, so it seems to be something about the dust.

I got the inlay done by filling the voids with glue and then dropping dust into it and rubbing it in with a finger, and the end result seems to be about the same as premixing and filling in a civilized way. I'm just wondering if anyone knows what it is about rosewood dust that's different, and if I would get better results from using epoxy, or some other kind of glue?

Dec 3, 2022 - 5:47:49 AM

15095 posts since 6/29/2005

I know what you're talking about.  Some kinds of exotic wood will heat up actually smoke, and get as hard as a rock in seconds when mixed with CA.

If I have to match non-black wood, I use System Three 5-minute epoxy and mix a colorant like trans-tint and/or wood dust into it.  The epoxy doesn't darken the sawdust nearly as much as the CA does, and you can get a better color match.  You can scrape it flush after 15 minutes or so, eliminating a lot of sanding.

The other good thing for rosewood would be the old-school shellac stick -with-a hot spatula method, which is instantaneous and can be color-matched perfectly.

Dec 3, 2022 - 5:51:14 AM
Players Union Member

Helix

USA

16373 posts since 8/30/2006

I agree completely.
I found superglue to set up harder than epoxy.
It's more difficult to level afterwards.

For the Rosewood dust, it has to be the chemistry.

Dec 3, 2022 - 6:20:36 AM

54 posts since 8/13/2021

Hmmm, Rosewood dust.. Some species of the of wood(s) that we use, may have to be used with some caution. Eye, throat, as well as sinus irritation may be experienced, both in sanding to a finish, or mixing with a CA or similar adhesive. I find Rosewood and Cocobolo, and some Cedars are triggers on my personal sensitivity scale. Mask during use, and a good hand-washing and change of shop clothing after usually helps.. along with a good filtration system/vacuum, and not to rub my eyes.! Some probably more sensitive than others to this.. kb

Dec 3, 2022 - 7:45:12 AM

roydsjr

USA

828 posts since 5/17/2007

I fill in the cavity with the dust first then add the super glue. Then add extra dust just as soon as I can after the super glue is added. I use the dremel tool with a 1/2" drum sander to level the working area. Then hand sand the area to remove the scratches from the drum sander. This seems to work for me. I do the same with ebony.

Dec 3, 2022 - 12:49:18 PM

12477 posts since 10/27/2006

quote:
Originally posted by Zachary Hoyt

…. When I mix rosewood dust with the same glue it sets up rock hard within 5 seconds or so. I don't even have time to finish mixing it before it's gone off. When I put a drop of glue in the bottom of a hole to hold a dot it doesn't do this, so it seems to be something about the dust.


quote:
Originally posted by Ken LeVan

I know what you're talking about.  Some kinds of exotic wood will heat up actually smoke, and get as hard as a rock in seconds when mixed with CA.


The culprit is moisture. CA does not cure except in the presence of water vapor and too much H2O acts as an accelerant. Way too much causes the exact symptoms you describe. Medical grades of CA are formulated not to react as violently with the moisture in your skin but the effect cannot be mitigated completely or it wouldn't cure at all.

If I want superglue to set up quickly, I exhale into the spot before and after I apply it.

You can try putting some of that rosewood dust in a microwave for a few seconds to dry it out a bit. A toaster oven will cause it to burn. Like with old recording tape, the ideal heater is a jerky drying oven set at 110° or so but I wouldn't buy one just for that.

Dec 3, 2022 - 1:27:27 PM
Players Union Member

Helix

USA

16373 posts since 8/30/2006

Brilliant

Dec 4, 2022 - 7:25:43 AM

heavy5

USA

2548 posts since 11/3/2016

CA succumbs to moisture over time & IMO has no place on a stringed instrument .

Dec 4, 2022 - 1:10:59 PM

237 posts since 5/27/2008

Heavy5 how much time are you thinking? I know of banjos that have had inlays glued with CA in them for at least 20 yrs with no bad effects.

Dec 4, 2022 - 1:42:09 PM

heavy5

USA

2548 posts since 11/3/2016

It depends on the CA & the environment . If a drop of CA is used as a positioner under the inlay , w/ an epoxy mix for a filler , no worry . I have seen CA turn white & crumbly used on models , so from experience , it does happen & I've seen it written ,

Dec 4, 2022 - 3:05:24 PM

2444 posts since 2/7/2008

When I use sawdust and epoxy as filler for woods other than ebony, I mix in a little colloidal silica. The silica prevents the sawdust from getting too dark when the epoxy saturates it.

Dec 4, 2022 - 8:00:29 PM

12477 posts since 10/27/2006

quote:
Originally posted by heavy5

CA succumbs to moisture over time & IMO has no place on a stringed instrument .


CA fills and nut repairs that I did 50 years ago are still holding up. OTOH, Superglue will weaken if exposed to hot water, that is well known.

 

More cool facts:

https://www.todayifoundout.com/index.php/2011/08/super-glue-was-invented-by-accident-twice/

Dec 5, 2022 - 8:05:21 AM

B0bIII

USA

97 posts since 4/2/2009

All types of dust will do that with CA.
Fill the void with dust then drip thin glue onto it. The glue should seep in about 1/8" deep at a time.
Blowing moisture on it will cause it to haze as it cures, better to use the accelerator stuff if looks matter.
Using the CA glue as a finish on the piece will hide the dust/glue repair a lot better. It makes a good finish for softer wood, because it kind of case hardens it. The fumes really become an issue at that point.
Epoxy is probably a better route for inlay.

Dec 6, 2022 - 3:25:27 PM

3221 posts since 2/18/2009

Thank you all for your input. With the glue I use (the thick #30 from Stew-Mac) the only wood that seems to do this quick set up thing is rosewood. Ebony is fine, also walnut and jatoba. I can't remember trying any others. I think the moisture level is similar through all of these woods at the time I have used them, as they have all been stored in the same shop for some time.

I can't use shellac or anything other than sawdust because I'm colorblind. The sawdust is not a perfect match but it's better than anything else I can do.

I don't seem to react to rosewood, but the one time I used cocobolo it made me sneeze the first time I cut it on the bandsaw, and every time I cut or sanded it after that. Since that neck was made I have sworn off cocobolo and won't work with it. It seems like there is a individual variation in how people react to different woods.

Dec 8, 2022 - 6:48:07 PM

254 posts since 8/12/2019

On a side note I have actually burned myself badly mixing rosewood dust and CA before. I’m surprised no one here knows exactly what the chemistry is but I can second Ken’s comment about it smoking at (rare) times. Imagine gluing a lit match head to your fingertip and you’ll get the idea.

I like to test pieces of scrap as filler with rosewood, the rosewood dust typically darkens way too much to blend in once glued. Try 50/50 walnut and rosewood, or some other intuitive experiments. I also fill with dust, then flood with glue, then mound dust again on top, then sand. Typically a couple times is necessary to get over-flush. I ended up using Titebond with the combustible rosewood, it worked fine but it was a little painstaking. I need to learn to use epoxy though, that’s probably the solution here.

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