Super
glue is frequently used as a temporary fixative in assembly of kiln
forming projects. There is some concern about safety, as it is known
that super glue is made from cyanoacrylate, which it is feared will
break down in the kiln into cyanide gas.
Greg
Rawls, a certified industrial hygienist says "I looked at the
MSDSs for several forms of super glue. The main component is Ethyl
2-cyanoacrylate, which has a TLV of 0.2 ppm which is relatively
toxic. [However,] the thermal decomposition products are carbon
monoxide and carbon dioxide. I did not see a reference to cyanide
gas. However, as I recall cyanide gas dissociates into elemental
carbon and nitrogen at about 800 F. Since you use it in such small
quantities, I would not worry about it. In my opinion the worst thing
that could happen is you glue your fingers to the glass."
Safety
issues
To
treat the safety issues seriously and determine if you feel Greg Rawls' view is justified, you need to look at the issues of
toxicity, reactions, adhesion of tissue, ventilation, first aid and
decomposition products in the whole context.
Toxicity
The
fumes from cyanoacrylate
are a vaporized form of the cyanoacrylate monomer that irritate
sensitive membranes in the eyes, nose, and throat. They are
immediately polymerized by the moisture in the membranes and become
inert. These risks can be minimized by using cyanoacrylate
in well ventilated areas. About 5% of the population can become
sensitized to cyanoacrylate
fumes after repeated exposure, resulting in flu-like symptoms. It may
also act as a skin irritant and may cause an allergic skin reaction.
On rare occasions, inhalation may trigger asthma. There is no single
measurement of toxicity for all cyanoacrylate adhesives as there is a
wide variety of adhesives that contain various cyanoacrylate
formulations.
The
United States National Toxicology Program and the United Kingdom
Health and Safety Executive have concluded that the use of ethyl
cyanoacrylate is safe and that additional study is unnecessary.
2-octyl cyanoacrylate degrades much more slowly due to its longer
organic backbone that slows the degradation of the adhesive enough to
remain below the threshold of tissue toxicity, so the use of 2-octyl
cyanoacrylate for sutures is preferred.
Reaction
with cotton
Applying
cyanoacrylate to some materials made of cotton or wool results in a
powerful, rapid exothermic reaction. The heat released may cause
serious burns, ignite the cotton product, or release irritating white
smoke. Users should not to wear cotton or wool clothing, especially
cotton gloves, when applying or handling cyanoacrylates.
Adhesion
of the Skin
Various
solvents and de-bonders can be used. These include:
Acetone
commonly found in nail polish remover, is a widely available solvent
capable of softening cured cyanoacrylate
Nitromethane
Dimethyl
sulfoxide
Methylene
chloride
Commercial
de-bonders are also available.
Warnings
include:
- It is a mild irritant to the skin.
- It is an eye irritant.
- It bonds skin in seconds.
- Any skin or eye contact should be copiously flushed with water and medical attention be sought immediately.
- Do not attempt to separate eye tissues – the bond will separate naturally within a few days.
Precautions
- Use goggles.
- Do not wear cotton or wool clothing while using super glue
- Ventilate the area well. Since cyanoacrylate vapours are heavier than air, place exhaust intake below work area. Activated charcoal filters using an acidic charcoal have been found effective in removing vapours from effluent air so the bench top air filters are suitable for use while using super glue.
- Avoid use of excess adhesive. Excess adhesive outside of bond area will increase level of vapours.
- Assemble parts as quickly as possible. Long open times will increase level of vapours.
Evaporation
Effects
- The effects of heating cyanoacrylate are not completely known. The flash point is known to be greater than 85ÂșC. As a precaution do not remain in the area of the kiln after that temperature has been reached.
- The decomposition products are carbon monoxide and carbon dioxide. There is no reference in the literature to cyanide gas. It is highly unlikely that heat will cause the release of cyanide gas at any time during the heating. To be certain, you should make sure the evaporation of the glue is be complete before firing the kiln.
See
this tip for the use of super glue in kiln forming.
https://www.sciencedirect.com/science/article/abs/pii/S0379073811002726?via%3Dihub
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