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Epoxy
Epoxy is an extremely tough and durable synthetic
resin comprised of two parts that when mixed
together bonds a wide variety of materials
in relatively harsh conditions. However,
not all epoxies are designed for bonding
(some are used for patching, for example),
so be sure to select an adhesive epoxy if
that is your objective.
There is a multitude of adhesive epoxy products
available, many with different characteristics
that are intended for very specific use and
conditions. To help you choose the right
epoxy, here are some of the characteristics
to consider:
| Characteristic |
Importance |
| Pot Life |
Epoxy is stored in two parts because once
the two parts are mixed, the chemical reaction
that hardens the epoxy begins and cannot
be stopped or reversed. Consequently, if
you want to work with a batch of epoxy for
a while rather than constantly mixing up
new, small batches, make sure it has a long
pot life. |
| Setting and Curing Time |
Epoxies "set" (the time for them
to begin gripping) and then "cure"
(the time for them to reach maximum strength).
Be sure to investing these characteristics
if the bonding is to be done overhead or
where the two pieces cannot be clamped together.. |
Temperature
and Moisture |
Since epoxies "cure" rather than
dry, the evaporation of moisture is not a
part of the hardening process. However, exposure
to water or high humidity and to cold and
heat can still affect the setting rate, curing
time, and bonding properties of most epoxies.
Be sure to investigate these characteristics. |
| Elasticity |
Depending on the application, you may wish
the epoxy to cure firm or flexible. The higher
the elasticity, the more rubber like the
bond and thus the more flexible the adhesion.
This is especially important when the surfaces
bonded shrink or flex from temperature, humidity,
or stress. |
| Bonding Surfaces |
Not all epoxies will adhere to a particular
surface as well as to others. Choose your
epoxy based on the materials you want to
join together. |
| Toxicity and Combustibility |
A very important consideration when the epoxy
will be used indoors or subjected to heat,
sparks, or flame. Check for the toxicity
of the fumes given off during setting as
well as the epoxy's combustibility once cured. |
To learn about marine epoxies, click here.
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