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Figure 1

Figure 2

Digital kitchen scales are ideal for
weighing out small amounts of
material

An excellent filleting compound can
be made with a mixture of hard filler and cellulose fibres.

Low density fillers such as
hollow glass micro-spheres and phenolic micro-spheres can be mixed with epoxy
resin to make an easy to sand low density filler. However, a pre-mixed filler
such as Easy Fair is easier to use and is dust free when mixing.

Fumed or colloidal silica is
used as a thixotropic  (thickening) agent but it must be mixed in with a
high sheer mixer to avoid making the resin brittle. Garamite is a better
thixotropic agent because it can be stirred in by hand.

Reactive Resins stocks numerous
other fillers and additives. Please ask if you do not see what you
require.

HEALTH AND SAFETY

Reactive Resins provide safety data
sheets for all products. We send then automatically with commercial orders and
they are available from our web site or by post upon request.

Our epoxy resins are non toxic
but they are irritants and being viscous and sticky are difficult to remove from
skin. Our hardeners are also non toxic but some are corrosive and will cause
nasty burns if allowed to stay in contact with skin for any length of
time.

Always
use rubber gloves when using epoxy materials. Long nitrile gloves are best
because they resist solvent better than most other types. If rubber gloves are
to be worn for long periods also use barrier cream and wear cotton under-gloves
to prevent dermatitis. Always clean gloves with a solvent soaked rag before
removing them. Do not clean hands with solvent, it will penetrate through the
skin and also remove the natural oils from the skin and cause cracking and
dermatitis.

Some of our coatings contain solvents. Some solvents are
potentially more hazardous than epoxy resins and hardeners. In addition to being
flammable they have low occupational exposure limits, therefore coatings that
contain solvents should be used outdoors or in areas with adequate ventilation.
If ventilation is inadequate or if the product is being sprayed, it is essential
that all personnel in the area wear air fed masks or masks fitted with filters
that are approved for use with organic solvents. Dust masks will not offer
protection from solvents.

When sanding epoxy coatings, fillers etc always wear a dust
mask. Partly cured resins contain free amines and other chemicals that may be
potentially dangerous if inhaled.

Cellulose fibres are excellent for
giving body to the resin to enable it to be used more easily as an adhesive and
improve its gap filling properties. Grey cellulose fibres are inexpensive and
can be used where the finished product will not be visible. White cellulose
fibres are more expensive but are better where the finished work will be seen.

Hard fillers
such as powdered calcium carbonate, dolomite or solid glass micro-spheres can be
incorporated with epoxy resin to make a moulding or casting compound. The
viscosity of the mixed product varies according the the amount of filler
added.

Cellulose fibres thicken epoxy resin
to make an excellent gap filling adhesive.

Figure 1 shows a molecule of a common
epoxy resin made with bisphenol A.

Figure 2 shows a polyamidoamine
hardener molecule used for the manufacture of ‘hardeners’. An epoxy group can
react with an amine group (NH2 or NH) by displacing its hydrogen atom. The polyamidoamine
molecule in figure 2  has 5 amino nitrogen atoms and can therefore react
with 5 epoxy groups.

In order to obtain the best properties and maximum performance
from a cured epoxy system it is necessary for all of the epoxy and amine groups
to have reacted together to form a cross-linked thermoset resin. It follows that
it is essential that the correct amounts of each component are intimately mixed
together before use.

Slightly out of
balance ratios will only cause minor reductions in the physical properties of
the cured resin but large proportioning errors will reduce heat and water
resistance and strength, and increase elongation. Serious proportioning errors
will cause the resin not to cure at all and to form a sticky mass. Never try to
accelerate or retard pot life by varying the amount of
hardener.

SYNTAC
epoxy resins and hardeners are manufactured with many different types of raw
materials that are selected to provide particular properties such as cure speed,
strength, flexibility, adhesion, viscosity, water or oil resistance,
etc.

All epoxy resins molecules contain at
least one reactive epoxy group although most have two or more.

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EPOXY INSTRUCTION
GUIDE

MIXING
Thorough mixing is also critical to the correct curing of the product and
although small amounts can easily be mixed by hand, a spiral mixer used in a
pneumatic or cordless drill is essential for mixing larger amounts. The pot life
that is stated in the products literature will depend on the amount mixed and
the ambient temperature. Large volumes and higher temperatures will shorten pot
life. Pot life can be extended by pouring the mixed material into trays which
will allow the exothermic heat generated by the curing reaction of the resin and
hardener to dissipate.

CURING
SYNAMIN ambient cure hardeners will cure down to 8oC but the physical properties
of the cured resin will be less than when cured at higher temperatures, SYNAMIN
heat cure hardeners must be cured according to the specified
schedule.

FILLERS & ADDITIVES

There are numerous fillers and
additives that can be mixed with epoxy resin to make it suitable for a wide
range of applications. A few examples are given below.

WEIGHING RESIN &
HARDENER We recommend the use of digital scales to
weigh out the resin and hardener. Digital kitchen scales are sufficiently
accurate to obtain excellent results and are much easier to use than the spring
type. The scales shown are accurate to 1 gramme and cost less than £10.00.
Simply tare off the scale, pour out an approximate amount of resin, calculate
the amount of hardener required, tare off the scales again and accurately weigh
out the hardener. Proportioning pumps can be used with low viscosity resin but
they can be inaccurate and often clog if left
unused.