Fibreglass
Fibre Reinforced Plastics…...
FRP....Fibreglass
Safety and Composites
•Respiratory protection
•Skin Protection
•Eye protection
•Hearing protection
•Consideration of others
Strand magnified at 1000x
Tools and Materials
•
•
•
•
•
•
•
•
Grinders
Sanders
Cut-off saws
Die-grinders
Air chisel
Blow gun
Heat gun
Pneumatic/manual
• Masking materials
• Repair materials
• Glass cloth
• Clamps/fasteners
• Cleaners
• Safety equipment
• Clean up materials
adhesive applicator guns
Surface Preparation
• The first step in any successful repair is the
appraisal of the surface
• Wash the panel with warm soapy water to
remove water soluble contamination then rinse
clean
• Once dry, clean all panels with the appropriate
wax and grease remover so as to float all
(solvent soluble) contaminants to the surface
Tools, Equipment and
Abrasives
Cleaning
•Acetone
•Brushes
•Containers
•Safety!
Sanding & Grinding
Grinding Disc Grits
•50 grit
•40 grit
•36 grit
•24 grit
Differences in Sandpapers
Aluminum Oxide
Silicon Carbide
Garnet
Aluminum Zirconia
Grinders / Sanders
Single Action vs. Dual Action
Sandpapers And Their
Application
• 36-50 grit is used for damaged material
removal, as well as primary shaping and
beveling prior to repair procedure
• 80-120 grit is used for shaping of the repair
bevel, primary featheredging
• 150-180 grit is used for back sanding, final
smoothing and featheredging prior to primer
surfacer application
Fibreglass is a Plastic?
Fibreglass
• Fibreglass is made up of three basic
ingredients:
– fibreglas mat
– resin (polyester or epoxy)
– catalyst
•Reinforcing fabric must
be of loose construction
to allow repair adhesive
to penetrate and ‘wet’
the fabric
Types of Fibreglass Mat
• CHOPPED STRAND MAT (CSM).
- The most common fibreglass reinforcement, is made
up of randomly arranged glass fibre strands,
pressed and held together with a binding agent.
- Available mainly, in three different weights, one,
one and half, and two ounces per square foot.
Metric equivalents are 300g, 450g, and 600g per
square metre, or GSM.
- CSM lends itself ideally to most laminating jobs
including, boatbuilding, car body, roofing, ponds,
etc.
•Chopped strand
•Continuos strand
Woven Cloth
• Glass fibre filaments, spun into a yarn
then woven to make cloth, provides great
strength with minimal thickness, is
usually used as an alternate layer
between CSM, giving added strength
without substantially increasing laminate
thickness.
•Uni-directional E-glass
•Bi-directional E-glass
•Woven Roving
New Technology
•Kevlar
•Carbon Fiber
•Production Application Methods
•Chopped strand roll
for use with chopper gun
•Gel coat
•Gel coat is used as a finish coat
•To add colour to the product
•Is UV protectant
•Can be multi colour
•Applicator Gun
•Epoxy Resins
Resins
• Polyester resin is usually available as a twocomponent system, with resin in one container
and the hardener often known as the catalyst in
the other.
• Some systems use a catalyst and a promoter to
activate the resin. It is important to note that these
two products should not be mixed together prior to
mixing with the resin. Fire or explosion may occur
• It is important to note that FRP resins cannot be
used on SMC repairs!
Resins continued...
• Resin and catalyst (hardener, activator)
are mixed by quantity (ounce or milliliter)
• Rule of thumb: 1 oz. resin requires 10
drops of catalyst to cure correctly
• Incorrectly measured resin will have
adverse effects on the repair
Not following
recommended curing
guidelines can lead to
product failure
Assuming one manufacturers procedures will
work for others can be a
costly mistake
Never cure any repair
Above 225° F. Curing
Fibreglass is ideally done
At 140° F for 30-45 minutes
One Sided FRP Repair
Two Part Repair Materials
Damage Identification
• One of the most
critical steps in
assessing damage
to FRP is to note
where the damage
ends.
Great care must be
taken to note all
cracks and fractures
are removed
One sided repair materials
- Cleaner
- soap and water
- wax and grease remover
- Repair material
- cosmetic
- panel patching adhesive
- Abrasives
- 36 to 50 grit grinding disc for beveling
- 80-100 grit for featheredging damage
- 120-220 grit for shaping and smoothing
Preparation
-When beveling the
damaged area, make
sure all of the scratch
or gouge is removed
and the bevel is 2-3”
away from the centre
of repair area and all
paint material is removed from the
immediate area
Follow manufacturers
guidelines as to drying
and recoating times
Always finish imperfections (pinholes etc) off
with same material or
if acceptable use a high
density cosmetic
filler
Two Sided FRP Repairs
Types of two sided
damage
- damage that penetrates the panel and breaks the
reinforcing fibres
-large crack
-fracture
-hole
- damage results in pieces missing
-broken or missing pieces
-hole
Two sided repair materials
Cleaning
- use recommended
cleaners
Adhesive
- panel patching
adhesive
Filler
-cosmetic
-structural
Reinforcing fabric
Appropriate abrasives
Cleaning Fibre reinforced parts
Soap and water
-removes water soluble contaminants
-use a wash mitt or sponge
-rinse thoroughly with water
Wax and Grease remover
-may be needed on heavily contaminated parts
-use of scrub brush may be used
-should not be applied to the damaged area
Plastic cleaner
-Liquid or aerosol
-can be called a “mild” wax and grease remover
-may contain alcohol
-do not apply to the damaged area or broken fibres
Using cleaners
-do not use a solvent soaked rag
-apply solvent to the surface of the panel so as to float
contaminants to the surface
-pour or spray on
-always use clean cloths to wipe solvents
-always wipe in one direction to prevent recurring
contamination
Repair procedure
-clean area as to manufacturers recommendations
-on the exterior side of the panel, create a bevel with
appropriate grinding disc, making a gradual taper 1 1/2”
wide, leaving no sharp edges
-remove all loose material
-prepare the back of the
panel by removing any
loose material
-sand the area to receive the reinforcement
patch
-wipe, then blow the panel
clean
Reinforcing the panel back
-the back of the panel is reinforced to provide strength to
the panel and the repair
-a backing patch can be used
-built up from layers of reinforcement material and
adhesive (pyramid patch)
-made as thick as the panel to be repaired
-backing panel can be used
-cut from scrap SMC or FRP having a similar contour
to the damaged panel
Front reinforcement
-proper reinforcement of the front of the panel will allow
repair to remain hidden through temperature change
-try to copy the amount of reinforcement in the original
panel
-reinforcing strips should be cut according to the position
they assume in the
cavity, from the
smallest to the largest
1. Cut several pieces of
of reinforcing fabric
large enough to overlap
the damaged area by 2”
2. Use as many pieces as
deemed necessary to
duplicate the thickness
of panel to be repaired
3. Lay out a piece of wax
paper or aluminum body
tape larger than the
reinforcement patch will
be
4. Mix repair adhesive
5. Sketch out the rough dimensions of the patch on the wax
paper or body tape
6. Apply adhesive to the wax paper or body tape to a
uniform thickness is achieved with a plastic spreader
7. Begin laying out reinforcing fabric, applying more adhesive
between each layer to achieve saturation, stopping between
layers to use wax paper and a saturation roller to remove
any air pockets (do not leave wax paper between coats)
8. Alternate this procedure until appropriate layers of cloth
and repair material have been achieved to match thickness
of panel being repaired
9. Apply patch panel, and allow to cure in place, heat may
assist in cure time
A backing panel can
be made of scrap SMC
with a contour matching the panel being
repaired
Making a backing panel
1. Cut a piece of SMC which overlaps the damage about
2-3” all around
2. Grind or sand off paint or primers from the front of the
backing panel and wipe or blow off
3. Clean and sand the backside of the panel that will receive
the patch approx.. 3” all around
4. Apply a 1/2” bead of adhesive
all around the edge of the
backing panel
5. Press the backing panel into
place until the adhesive has
100% contact all around
6. Smooth out excess material
Completing the repair using a bridging strip
- A bridging strip is usually needed when sectioning a panel
- Adds reinforcement to
the repair
- Helps minimize shrinking
caused by changes in
temperature
Making a patch panel
-patch repair can be
made if a similarly
shape panel is available
-uses a square or
rectangle hole
-requires bonding strips
To make a patch repair: 1.clean the damaged part
2.cut out the damaged area keeping the cuts as straight as
possible
3.cut bonding strips about 2” wide and fit them around the hole
4.remove all paint from bonding strips
5.clean and scuff backside of panel where the bonding strips
will be applied
6.apply a 1/2” bead of adhesive to the bonding strips
7.secure the bonding strips in place with screws or clamps
until adhesive cures
8.cut and fit patch panel, leaving at least 1/2” gap all around
9.clean and scuff sand the back of patch panel
10.apply adhesive to the bonding strips and secure panel into
place
11. remove the screws
12. use a grinder to make
a 2-3” bevel on either
side of the gap between
the damaged panel and
the patch
13. blow or wipe clean
14. cut enough reinforcing
material to fit into the
taper
15. apply adhesive to the
taper, then lay reinforcing cloth, more adhesive,
more cloth, until height
is achieved. Finish with saturation roller and wax paper