Inside Story on Instant Adhesives
Luthier finds answers to his super glue questions
IN THIS ARTICLE
| Fumes |
Effectiveness of Accelerator
| || Opaques |
Mysterious blue rings
THE REPAIRMAN'S CONCERN
Dan Erlewine shares his quandary:
I was refretting a Gibson Montana-made flattop and using a soldering
gun to heat the frets before pulling them. While it loosened any glue
that may have been used in fretting, I was repulsed by the smoke and
odor. It seemed more noxious than usual, and then I realized why: the
frets were super glued in.
I wondered: "Since super glue is a cyanoacrylate product, am I
breathing heated cyanide fumes, or what?" Worried that I might get
sick, I opened all the windows, turned on the fan, put on my spray respirator and finished removing the frets. I vowed to
find out more about heated super glue fumes, and super glue fumes in
general, because this wasn't the first time I'd experienced the smell.
We'll all be removing more frets that were originally super glued — the
first wave is just now coming through. Here's how the chemist who
formulated our super glue answered some of the more common
questions we are asked about super glue.If you have a question, or
a tip about instant adhesives, please send it to us!
THE CHEMIST ANSWERS
Here's the word from the chemist:
Cyanide is used in the manufacturing process, but it's not present at
all in the bottled glue. The fumes, heated or unheated, are somewhat
noxious, as is any smoke you breathe, but less so than many other
products used in woodshops, such as ones containing methylene chloride
or toluene (paint stripper and lacquer products respectively).
Super glue in uncured form is 80 to 85 percent pure ethyl-based
monomer, but there are no solvents in it. The remaining 15 percent is a
stabilizer, a polymerization inhibitor, and a thickening agent — none
of which is particularly harmful. Super glue and its fumes are an
irritant to the mucous membranes however, and when you heat super glue
or put it on a hot surface the fumes are definitely unpleasant.
The Accelerator, which hastens the glue's curing time, is
primarily heptane, a relatively mild acetone-like solvent that flashes
off quickly and leaves the curing agent behind. (The curing agent is a
proprietary substance which is dissolved in the heptane carrier). I
won't tell you what it is, only that it's no more toxic than the
carrier itself. Accelerator is flammable, the fumes aren't good to
breathe, and you should treat it with the same cautions and
restrictions you would gasoline. Work in a well-ventilated area, handle
it with nonporous protective gloves, wear eye
protection, dispose of contaminated papers and rags outdoors, and
keep it away from food, pets, children, and pregnant women."
How long does accelerator remain active in the area where it's
It's commonly said that accelerator retains its potency, or ability to
harden super glue that comes in contact with it, for 45 minutes.
However, it has the potential to remain potent for as long as three
hours. I'd wait that long if you want a guarantee that glue applied in
the same area won't accelerate.
How long would you clamp projects with the different glues?
It depends on the application. For thin glue joints the clamp time is
going to be faster than fractures and areas where the glue is applied
thick and used like an epoxy. For the average well-fit part expect the
following set and clamp times:
Sets in 3-5 seconds,
but you may wish to
clamp it for up to 2
Sets in 10-25 seconds,
but you may need to
clamp it for up to 3
Sets between 30
seconds and up to
All these glues don't get a true cure for twenty-four hours, and
of course set and clamp times are substrate dependent. For example, on
rubber, cyanoacrylates usually set in 1 to 2 seconds, which is much
faster than for other substrates.
Do the opaque glues lose strength or hardness because of the
colorant added at the factory?
No it doesn't. Not at all. The black super glue is handy for working on
ebony fretboards and bridges. Both the black and amber super glues
are ideal for touching up gaps and repairing bindings.
[Dan gets a little more specific] Let's say I wish to use the
#20 medium glue to make a clear fill in a 1/8" deep
indentation — it might be wood or finish. I've been touching a little
Accelerator to the bottom of the hole to ensure that it
dries on the bottom, and then repeating the process in layers until the
hole is full. Sometimes a white or blue edge appears on the crater, and
sometimes it doesn't. Sometimes the whole mess gets frosty or frothy.
What determines if this will happen or not? What causes the
blue-white ring? Is that a blush?
Super glues are moisture-curing adhesives that react to water or
moisture present in the air, or in the pieces being glued. This is why
super glue "kicks off" so fast in humid areas and during the summer, or
why some days your drop fills are clear, and some days the white ring
appears. You can make perfectly clear drop fills by using only super
glue and letting it cure for 24 hours. All the super glues you're using
will be hard as rock in 24 hours if the application isn't excessively
Is there a shelf life for super glue?
Both super glue and accelerator have a one-year shelf life after
opening. Even then, the glue retains its strength, but is losing its
If you have a question, or a tip about instant adhesives, please send it to us!
StewMac Super Glue