TM 1-1500-204-23-11
b. Fibers. Aramid ibers must be stored out of
until moisture is no longer condensing on the pack-
direct sunlight to prevent ultraviolet radiation damage
age.
to the iber. Wear latex, nitrile or lint free cotton
gloves when handling dry fabrics. If powdered gloves
(1) Receiving Inspection. Upon receipt at the
are all that are available, ensure exterior of gloves are
operating activity, inspect containers for damage and
cleaned before handling repair materials and hands are
ensure material is within shelf life. Identify and imple-
washed thoroughly immediately after removal of gloves
ment proper storage conditions in accordance with
to prevent contaminating the area and materials.
the appropriate technical manual or manufacturer s
instructions.
c. Dry Fabrics. To prevent particulate contami-
nation, dry fabrics shall be stored in original shipping
(2) Epoxies. Epoxies are prone to storage,
containers or sealed plastic bags before use. After
handling, and processing issues. Some of the more
a roll of dry fabric has been opened, appropriate
common issues are carbamation, "amine blush", and
measures should be taken to prevent the accumu-
oxidization.
lation of particulate contamination on the material.
Fabrics shall not be exposed to grinding/machining
(a) Carbamation, Carbamation sometimes
operations. If this occurs, the outer layers of the
called carbonation, is the formation of ammonium
material roll should be disposed of to ensure clean,
salts at the surface of a mixed epoxy adhesive. The
uncontaminated material is used for repairs.
hardener, typically an aromatic or aliphatic amine
compound, reacts with carbon dioxide and water
d. Vacuum Bag Materials. Store the required
present in the air to form a barrier at the surface of
types of bagging and separator ilms, bleeders,
the adhesive. Undisturbed, this barrier can prevent
breathers, insulation, and other type bagging materials
wet-out and reduce the strength of the cured adhe-
in a location that will minimize airborne contaminates,
sive. Immediate assembly of bonded parts under the
such as a storage cabinet. Plastic covers are an
least humid conditions available reduces the likelihood
inexpensive method of protecting roll materials and
of this happening. Additionally, elevated temperature
can be used independently or in combination with
cures, above 160 F, tend to break down the car-
other protective measures. Separate the bagging
bonate barrier, sometimes producing bubbles in the
ilms from the bleeder, breather, and insulation cloth
adhesive, which can also decrease strengths.
to minimize contamination of the ilms from the cloths.
Store nylon bagging ilms in a clean area. Nylon has
(b) Amine "blush".
Sometimes called
a tendency to dry out in low humidity environments;
"sweating", or "bloom", Amine "blush" is the result
this will degrade the bagging ilm and shorten its shelf
of the same type of chemical reaction that causes
life. See the glossary for a description of bagging
carbamation. In this case, the result is an oily,
materials. Since moisture is the plasticizer in nylon
waxy or chalky deposit on the surface of the cured
bagging material, the nylon can become brittle when
adhesive. Possibly affecting the repair strength, blush
stored in areas of low humidity; strive to store it at
needs to be removed before conducting any painting
55 percent or higher relative humidity. One way to
or secondary bonding operations. Rinsing with clean
accomplish this is to store the nylon material in a
water, followed by sanding with ine-grit sandpaper is
closed container with a wet cloth inside. If immediate
the preferred removal method. Solvents will typically
lexibility is required, the roll can be restored by
not remove the deposits adequately and may cause
placing the nylon bagging material in a small tent
undesirable swelling of the cured epoxy.
with a steam vaporizer for 4 hours.
(c) Oxidization. Do not leave resin com-
e. Laminating Resins and Paste Adhesives Stor-
ponents exposed to the environment for an extended
age. Laminating resins and paste adhesives must
period of time. However, during normal use the open-
be stored in clean containers and in accordance with
ing and closing of the Part B container causes it to be
manufacturer s instructions. The containers must be
exposed to a certain amount of fresh air. Over time,
kept closed to prevent moisture absorption which will
especially at warmer temperatures, this can cause the
degrade the resin properties. Most two-part systems
hardener to react with oxygen in the air (in addition
should be stored around 75 F; higher tempera-
to the carbon dioxide and water absorption previously
tures often shorten the shelf life. Shelf life limitations
mentioned). This is called oxidation. The result may
imposed by the manufacturer must be observed; con-
be a slow darkening, or discoloration of the hardener
sult the manufacturer s technical data sheet for storage
and/or an increase in viscosity (that is, a decrease
options and their effect on the shelf life. Check the
in luidity). Such oxidation of hardeners is a fairly
shelf life of each component; they may be different.
common condition and does not appreciably affect
Before opening refrigerated materials, the containers
the strength of the cured epoxy. Note that hardener
must be allowed to warm up, typically a few hours or
color may vary one batch to the next. Therefore,
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