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[kent]

Long ago I was commissioned by a southern California luthier to make some stone switch replacements for a few electric guitars.
The pieces are relatively easy to make but I had great difficulty removing the tiny, fragile pieces from the brass rods I glued them to. I used 330 epoxy and afterwards soaked the rod and stone in acetone to try to soften the epoxy. I may have had a 35% success rate in removal of the rod from the stone  without damage.
I've been asked to make a few more for a Jerry Garcia "Wolf" guitar replica so I'm wondering if all you experience folks have any ideas for a glue that has the capacity to hold well during grinding and polishing and release when I'm done.


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Thanks

[lithicbeads]

You could use an epoxy as those mixes retain resiliency and do not become brittle with time.You should also look at Hxtal if you are not familiar with it as it is the most widely used glue for ceramic museum repairs and is very popular for stabilization of stones .I am not at all familiar with it's mechanical properties so you would have to look into it but it is very stable and uv proof. There are a lot of varying mechanical properties of epoxies but you should be able to find advice on the net.Be very precise on the mixing and have very clean surfaces.

[lithicbeads]

I would do some research on commonly available solvents as you might find a better chemical. I am not speaking of proprietary brands as they can have unwanted chemicals in the but rather  single chemical solvents.Wath your lungs.

[kent]

Hi Frank, long time....

I've been associated with a variety of epoxy resins (brands, formulations, ect)  due to my marine background. Thermosetting resins by large are impervious to softening once cured. The 330 epoxy I use is similar to the hxtal in that it cures clear and is variable to jewelers and lapidaries.
Heat can somewhat soften cured epoxy however my little rock switches probably would crack in high temps due to their thin side walls.

I did a little searching and found a product called "Attack" which is claimed to be an epoxy (cured) solvent. I may try that.
Methylene Chloride is an epoxy solvent but highly volatile and way too strong a chemical for my shop (and my lungs).

I may do an experiment with super glue as I have a solvent that has, in the past, unglued my fingers.....

Thanks for the input and I hope life is easy for you !

Cheers

Kent

[R.U. Sirius]

Various solvent mixtures marketed for the purpose actually work quite well, with the caveat that the speed of the process will depend on the surface area available for the solvent to act on (to penetrate through), and also on the overall amount of epoxy and the geometry of the bonded area. For example, if the bond extends deep into the cavity, it might take many days or even weeks for the softening and debonding to complete.

You will have much better success if you carefully consider and control how much epoxy you are using, and where exactly. The less, the better. Ideally, just a ring around the outside contact area between the stone and the brass rod should be enough, and should be easy to debond. Keep in mind that many epoxies tend to wick into narrow gaps as their viscosity temporarily drops in early stages of curing.

Solvent vapours are of course not good to breathe, and some are actually quite bad, but it is possible to do this job safely if you are reasonable about reading and understanding the safety data sheet, product instructions, and use proper ventilation, sealed jars if appropriate, PPE.

Some examples are plain methylene chloride, NMP, MEK, or their mixtures. Commercial stuff like MS-111 and dynaloy.

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If you use PVC or ABS or acrylic instead of brass, you could dissolve it easily in good-old acetone.