the material they are made from, such as Polyvinyl
tailored to meet composite part manufacturer s needs
Fluoride (PVF), FEP or Polytetralouroethylene (PTFE
and are available in different weights (thickness) and
or Telon®) coated iberglass. Both the ilms and
different levels of conformability. For most ield repair
the fabrics are available in porous or non-porous
applications, 4 ounce polyester breather is suficient.
forms. The non-porous release ilms and fabrics are
interchangeable; their purpose is to stop resin low
from the bleeder plies into breather plies. Porous or
Only use lashbreaker tape inside the vacuum
perforated release ilms and fabrics have small holes
bag. Other tapes will contaminate the bonding
which allow excess resin to bleed out. The size and
distance between perforations, in combination with the
bleeder cloth used, directly affects the resin content
4 Tapes. There are two types of tapes
of the cured component; therefore, you must use the
used in vacuum bagging Flashbreaker tape and vac-
type speciied for your particular repair. The ability
uum bag sealant tape.
of the thinner ilms to stretch can make them dificult
to apply to lat surfaces without wrinkles.
a Flashbreaker Tape. Flashbreaker
tapes are used to hold thermocouples and other
(a) Porous or Perforated Release Film
materials in place inside the vacuum bag. Flash-
Porous release ilm, also known as porous parting
breaker tapes are usually made from 2 to 5 mils thick
ilm, or separator, is placed between the repair plies
polyester ilm and have either a silicone or rubber
(or peel ply, if used) and the bleeder cloth. Gas low
adhesive on one side; the rubber adhesive is pre-
and resin bleed out through the ilm, and the bleeder
ferred if there will be subsequent bonding operations.
plies are prevented from bonding to the repair plies
They are available in a variety of widths and typically
during the cure cycle.
have a 1 year shelf life. Because the lashbreaker
tape is not part of the completed repair, the shelf life
1 Bleeder. Bleeder cloths can be made
is not critical and the tape can be used as long as it
from woven or nonwoven cotton, polyester or iber-
has suficient tack. For ield repairs, 1 inch wide, 2
glass. They absorb the surplus resin from the repair.
mils thick lash tape with silicone adhesive is usually
When a speciic number and type of bleeder cloth
is called for in a repair, it must be used to ensure
the resin-to-iber ratio meet the repair requirements.
b Vacuum Bag Sealant Tape. Vac-
Too few plies of bleeder cloth may result in too much
uum bag sealant tape is used to seal the vacuum bag
resin in the repair; too many plies of bleeder cloth
to the part or tool surface. Sealant tape is usually
may result in not enough resin.
made of a synthetic rubber material, available in a roll,
1/8 inch thick and 1/2 inch wide. It is available with
2 Caul Plates. Caul plates are smooth
different amounts of tack or stickiness. Most have a
metallic or plastic plates used in a composite layup
shelf life of 9 months to 1 year, after which they lose
or on a repair part to distribute pressure and to
their tackiness. For ield repairs, a sealant tape with
provide a smooth surface on the inished laminate.
good or excellent tack is recommended. Duct seal is
Caul plates maintain contour with the assembly tool
not recommended because it is susceptible to leaks
to ix the part details in place. They also support the
bag over an area where the vacuum bag pressure
may cause local crushing at vulnerable edges. Metal
caul plates, usually aluminum or copper, are used to
distribute the temperature from the heat blanket more
Do not use nylon vacuum bag material for
evenly over the repair. The caul plate should be the
storing frozen materials; this material does
same size as the heat blanket. Sharp edges can
not provide an effective water vapor barrier.
puncture the vacuum bag and a non smooth surface
Nylon has a tendency to dry out in low humidity
can create resin rich areas.
environments; this will degrade the bagging
ilm and shorten its shelf life. It absorbs
3 Breather. Breather material allows air
moisture from the air making it more pliable
inside the vacuum bag to be removed and thus enables
and less likely to crack. In low humidity
atmospheric pressure to be applied to the area. It is
environments, such as a desert, do not use
made of a loosely woven or nonwoven material; it does
brittle material as it may rip or tear.
not come in direct contact with the part or repair area.
Fiberglass cloth or commercially available breather
5 Vacuum Bag Film. Vacuum bag ilm
materials may be used. The commercially available
is an impermeable plastic ilm such as nylon or PVF
breather cloths have been designed for improved
that covers the repaired area or completely envelopes
airlow over iberglass cloths. Breathers have been
the entire part (and the tool if used). It is sealed