a. Cure Process. During the cure process, the
resin system progresses from a liquid to a weak
gel and then into a strong, highly structured solid.
Pressure (either positive or vacuum) is applied during
Failure to observe the correct number of repair
the cure to facilitate resin low, degassing, compaction,
plies, the correct repair ply orientation, the
and to ensure bonded details remain in contact while
correct repair ply overlap and removal of all
the chemical reaction is in progress. The resin system
pieces of vacuum bagging ilm will reduce the
can be sanded usually within 8 to 24 hours after the
strength of the repair and may result in the
start of the cure process once the adhesive hardens.
loss of structural integrity.
Full strength of the resin system is not achieved
until 5 to 7 days after the initial mixing of the base
Layup: Flat Plate Collation Tech-
resin and the curing agent (unless heat is applied).
Cut a layer of release ilm at
least 1 inch larger than the
b. Limitations of Resins When in Use. When
largest ply of the laminate.
working with resins, be aware of these limitations
Tape to the lat surface.
which may affect the strength and life of the resin.
Remove one of the pieces
(1) Mixing Container. Use an approved type
of release ilm from the irst
container for mixing. Do not use wax-coated cups or
ply of the laminate and place
ones that can absorb liquids, or any container that
the resin impregnated surface
will react with the resin. When possible, use a lat
of the ply. Place the resin
ended mixing stick to ensure that resin in the corners
impregnated surface of the
of the container is adequately mixed.
ply onto the release ilm taped
to the lat surface in step (a)
(2) Storage. Do not allow pre-measured resin
above. Ensure the proper ply
to be stored in an open container for an extended
orientation is maintained. See
period of time as the resin will become contaminated
with moisture. This degrades the resin and it must
Remove the second piece
of vacuum bag ilm from the
(3) Batch Limitation Size. Do not exceed the
surface of the installed ply.
batch limitation size (include the quantity of both
components) when mixing the material in a container
Repeat steps b and c above
because the material may exotherm and create a
for the remaining plies until
hazardous safety condition.
all plies have been placed in
the proper stacking sequence
(4) Pot Life. Do not exceed the pot life (working
on the lat surface, while
life) of the material. Know how much time is required
maintaining the speciied ply
to properly mix the material, apply it to the repair, and
orientation for each ply in the
prepare the area for application of pressure and heat
application. Break up the batch into smaller quantities
and mix/apply them together to minimize exotherm
Transfer collated plies from
potential. Pot life is shortened when temperatures
the lat tool plate to the layup
exceed 77 °F.
tool or part. Form the plies
to the surface contour of the
(5) Disposal. Dispose of any excess uncured
layup tool or part and remove
resin in accordance with the local hazardous material
wrinkles using the adhesive
disposal procedures. Do not combine uncured materi-
als such that the accumulation will result in exceeding
the material batch size limitation. If this limitation is
6-17. RESIN PREPARATION AND USE. This para-
exceeded, the materials may exotherm and present
graph describes the cure process of a resin and
a smoke and ire hazard.
identiies the limitations associated with the use of
resins. Follow the steps in subparagraph c for resin