MODULE 3–APPLYING CORROSION PROTECTION MATERIALS
Topic A. Preparing Parts For Corrosion
Protection Materials
A-4 Removing contaminant with wax and grease remover helps ensure
adhesion of the corrosion protection material.
A-3 Some corrosion protection materials require the part to be sanded
with 80–150 grit sandpaper before application.
Replacement parts must be prepared for corrosion
protection application before, during, and after the
repair process. This requires removing dirt, rust, oil,
grease, and in some instances, paint and primer.
Two basic types of cleaning processes include mechanical and chemical.
Types of mechanical cleaning include sanding and
grinding panels or sand blasting (plastic media blasting). This should remove primer, paint, rust, oil, and
grease. If the galvanizing is intact, do not remove it
during mechanical cleaning.
Corrosion Protection Program 1 v.3.1–Module 3
© 2001 Inter-Industry Conference On Auto Collision Repair
Chemical cleaning is basically the application of wax
and grease remover. Wax and grease remover dissolves tar, oil, grease, and silicone by loosening
contaminants and floating them to the surface. Wax
and grease remover should not be substituted with
paint solvents.
When applying wax and grease remover:
1. Apply liberally with a clean cloth, keeping the
surface wet.
2. Wipe with a clean cloth before the solution starts
to dry. Use a wiping motion similar to wiping off
a table.
3. Turn the cloth at each pass. Reapply if bare metal
contacts skin.
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A-6 Metal cleaner and conversion coating is only necessary if recommended by the paint maker.
A-8 Check the coating on replacement parts to determine paint preparation steps.
Another type of chemical cleaner is the metal cleaner
with conversion coating. If recommended by the
paint maker, apply the metal cleaner and conversion
coating after the wax and grease remover.
Parts that are used to replace damaged parts must be
properly prepared before they are attached to a
vehicle. These steps may vary depending on if the
part is an OEM replacement part, non-OEM replacement part, or salvage part.
USING METAL CLEANER AND
CONVERSION COATING
Refer to screen A-7v of your CD-ROM for a
video on applying metal cleaner and conversion coating to a panel.
OEM replacement parts typically arrive from the
factory with E-coat primer applied. E-coats are usually 13–27 microns (0.5–1 mil) thick. Some may
require additional coatings to provide adequate film
build before applying topcoat. Other parts may only
need to be cleaned and scuffed and have the recommended primer applied.
Corrosion Protection Program 1 v.3.1–Module 3
© 2001 Inter-Industry Conference On Auto Collision Repair
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A-9 Check replacement panels for shipping coatings by wiping a solventsoaked rag on the panel and checking for material transfer.
Some non-OEM replacement parts are shipped with
a temporary coating for shipping and storage. Temporary coatings must be removed and the part
prepared for priming. If the coating type is unknown,
perform a solvent test.
To perform a metal panel solvent test:
1. Wet a cloth with solvent.
2. Following the paint maker’s recommendations,
hold or rub the cloth on a primed area. Keep the
area wet for the length of the test.
3. Check for material transfer on the cloth and for
softening of the coating.
A-10 Check salvage parts for any corrosion or signs of previous repairs.
If using a salvage or reconditioned part, examine the
finish to see if it has excessive film build. Salvage parts
could have been previously refinished without knowledge of the vendor. This would require the finish to
be removed to a level that allows the part to be
refinished without exceeding the paint maker’s mil
thickness requirements for their warranty.
The part should also be examined for corrosion.
Parts with moderate to severe corrosion should not
be used.
After determining that the panel can be used:
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Corrosion Protection Program 1 v.3.1–Module 3
© 2001 Inter-Industry Conference On Auto Collision Repair
clean the part with wax and grease remover and
examine the part for corrosion.
remove all existing corrosion from the part.
apply corrosion protection to bare metal areas.
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Topic B. Corrosion Protection
Application Equipment
B-2 Some anti-corrosion compounds have application equipment that is
custom designed for the product.
The spray guns may vary according to the type of
anti-corrosion material being applied. For example,
spray equipment may be designed for application of
thicker materials such as corrosion compound or
product-specific applications.
B-1 Gravity-feed guns can be used to apply self-etching or epoxy primers.
Self-etching and epoxy primers are applied with a
spray gun. Primer spray guns can be siphon or
pressure feed. To ensure adequate coverage, a spray
gun must provide the proper atomization and be
capable of spraying though application wands of
various lengths.
Application of primer must comply with federal, state, provincial, or state VOC regulations.
B-3 Spray wands for anti-corrosion materials can be flexible or rigid that
spray in a 360° or fan pattern.
Application wands are used to apply coating on
panel back sides and inside enclosed rail areas.
These wands are available in flexible form and different lengths.
There are also spray heads which distribute coatings
in either a 360° pattern or fan-shaped pattern.
Flexible wands are designed for specific product
applications. Using an anti-corrosion compound spray
wand to apply primer may cause too much primer to
be applied. If a primer wand is used to apply anticorrosion compound, the system may not be able to
spray the thicker material.
Corrosion Protection Program 1 v.3.1–Module 3
© 2001 Inter-Industry Conference On Auto Collision Repair
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TYPES OF CORROSION PROTECTION
APPLICATION EQUIPMENT
Select the Demonstration Icon found on screen
B-3 of your CD-ROM for a demonstration on
corrosion protection application equipment.
Topic C. Applying Corrosion
Protection On Exterior Panels
EFFECTIVENESS OF AEROSOL MATERIALS
ON PART INTERIORS
Select the Demonstration Icon found on screen
B-3 of your CD-ROM for a demonstration on
the problems associated with using aerosol products for
corrosion protection of part interiors.
C-1 Do not apply acid-etch primer under plastic filler.
Exterior panels include the outside of:
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B-4 Be sure to monitor the amount of product applied to the interior of
a part.
When using primers inside an enclosed area, be sure
materials selected for this process match the intended use by the paint maker. When applying
primers inside a rail or pillar, it may be difficult to
monitor film thickness and coverage. Applying too
much may prevent proper curing of epoxy primer or
self-etching primer. Follow the paint maker’s recommendations for thickness and equipment type.
fenders.
doors.
quarter panels.
hoods.
roofs.
rockers.
When preparing these areas for primer, make sure
the weld areas are dressed and appropriate filler
applied.
Next, apply either a self-etching primer or a two-part
epoxy primer. Remember that self-etching primer
should not be applied under plastic filler.
Check paint maker recommendations for application of self-etching primer. Self-etching primer is used
over bare or galvanized steel, however, it may not be
suitable for use inside enclosed areas.
CORROSION PROTECTION
APPLICATION EQUIPMENT
Refer to screen B-5v of your CD-ROM for a
video on corrosion protection application
equipment.
Corrosion Protection Program 1 v.3.1–Module 3
© 2001 Inter-Industry Conference On Auto Collision Repair
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SELF-ETCHING PRIMER APPLICATION
Refer to screen C-3v of your CD-ROM for a
video on applying self-etching primer to a
panel.
Topic D. Applying Protection To The
Panel Back Side
C-4 Epoxy primer is applied following metal cleaner/conversion coating
or over bare steel.
D-1 Exposed metal on panel back sides require restoration of corrosion
protection.
Check paint maker’s recommendations for application of epoxy primer. Epoxy primer may require an
etch primer or a metal cleaner/conversion coating
before application while some epoxy primers can be
applied over bare steel.
APPLICATION OF TWO-PART EPOXY
PRIMER
Refer to screen C-5v of your CD-ROM for a
video on applying two-part epoxy primer to a
panel.
Corrosion Protection Program 1 v.3.1–Module 3
© 2001 Inter-Industry Conference On Auto Collision Repair
The back side of panels that have been exposed to
collision repair processes (have hot spots) need to
have the corrosion protection reapplied. Examples
of parts include all panels both structural and nonstructural such as quarter panels, rocker panels, door
skins, and pillars.
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D-2 Stud welds will burn away the corrosion protection on the panel
back side. This protection must be restored.
Hot spots include areas such as bare metal on the
flanges of panels that have been replaced and areas
where picks, hammers, dollies, or stud welders were
used. An additional area commonly overlooked is
the rocker panel pinchwelds where clamps were
used to anchor the vehicle.
D-4 Using existing holes to apply corrosion protection to enclosed parts
such as rockers and pillars is the best method. Drilling holes is a last resort
process.
Corrosion protection to the back side of the panel
should be the same for any metal surface. However,
if the surface is not visible, it may not require the
application of topcoats. If there is limited access,
proper protection may require the use of an access
hole and flexible wand.
Drilling holes to gain access to the panel back side is
generally considered last resort and typically not
recommended by the vehicle maker. Questions to
be asked before drilling include:
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Is the energy management of the part being
altered?
Is another hot spot being created by drilling into
the part?
D-3 Using anti-corrosion compound and epoxy provide a close match to
the durability of OEM corrosion protection.
Material used to provide protection to the panel
back side include epoxy primer and anti-corrosion
compound. Using a combination of these two helps
provide a close match to the durability of OEM
corrosion protection.
Corrosion Protection Program 1 v.3.1–Module 3
© 2001 Inter-Industry Conference On Auto Collision Repair
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D-5 Only apply corrosion protection to the bare steel areas on the panel
back side.
E-2 Areas that are not visible may not require clearcoats and in some
instances, topcoats.
When applying corrosion protection to the panel
back side, only apply primer to the bare metal areas
on factory E-coated panels. Typically these bare
metal areas include pinchweld flanges, the back side
of a section joint, and hot spots where panel repair
was performed.
A consideration for application of corrosion protection in interior areas includes visibility of the area.
This requires making sure seam sealers match the
OEM appearance and that topcoats are applied.
Applying corrosion protection to factory E-coated
parts is not necessary since factory primer alone
provides sufficient corrosion protection.
APPLYING CORROSION PROTECTION
TO PANEL BACK SIDE
Refer to screen D-6v of your CD-ROM for a
video on applying corrosion protection to the
back side of a panel.
Topic E. Applying Protection To
Interior Surfaces
E-3 Some trunk floors close out structural parts. Therefore, corrosion
protecting the trunk floor now ensures the structural integrity of the
vehicle.
Enclosed interior surfaces include:
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top side of trunk floor.
engine compartment.
top side of floor pan.
core support.
inside doors (excluding skin).
Corrosion Protection Program 1 v.3.1–Module 3
© 2001 Inter-Industry Conference On Auto Collision Repair
Some interior parts close out structural parts (e.g.
trunk floor and rear rail), thus increasing the importance of corrosion protecting both sides of the panel.
When applying corrosion protection, avoid vehicle
electronic parts, wiring, electrical connectors, linkages, brake cables, etc.
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When applying corrosion protection to bolted-on
parts:
Topic F. Corrosion Protection For
Structural Parts
1.
2.
3.
4.
Clean with wax and grease remover.
Prime with epoxy or self-etching primer.
Topcoat when required.
Install fasteners, making sure they are properly
insulated when working with dissimilar metals to
prevent galvanic corrosion.
5. Apply anti-corrosion compound to panel back
side where repair work has been performed.
F-1 Long, rigid wands work well for accessing areas such as rear rails and
front rails.
Restoring corrosion protection to structural parts
ensures that the part does not fail during a subsequent collision or normal operation. Part failure may
cause possible injury to passengers. Structural parts
of note include pillars, rocker panels, crossmembers,
rails, and the windshield pinchweld.
E-5 Welded-on parts must be protected on the outside and inside of the
repaired area.
Applying corrosion protection to welded-on parts is
similar to the process for bolted-on parts. The differences are the application of weld-through primer to
weld zones and the application of seam sealer to
joints.
Avoid spraying the hood latch and rear hatch. Remove trim panels from doors for access and to
prevent overspray.
Corrosion Protection Program 1 v.3.1–Module 3
© 2001 Inter-Industry Conference On Auto Collision Repair
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Rocker
Panel
A-Pillar
F-2 Panel reinforcements require corrosion protection, such as weldthrough primer, be applied during assembly of the part.
F-3 A common use of weld-through primer is on the mating side of a
section insert.
Some part and joint designs can hinder application
of corrosion protection such as:
Common questions asked before applying corrosion protection include:
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butt joints with inserts.
panels with reinforcements.
pillars or rails without spray wand access.
panels with multi-layered reinforcements.
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Corrosion Protection Program 1 v.3.1–Module 3
© 2001 Inter-Industry Conference On Auto Collision Repair
when and where is weld-through primer best
used? Wherever there is bare metal in a weld
area, weld-through primer should be applied.
is it best to use sectioning inserts that have the Ecoat intact? Factory E-coat provides the best
protection against corrosion, therefore, if an Ecoated insert is available, it should be used.
should epoxy primer be applied before anticorrosion compound on the interior of a structural part? While one or the other may provide
protection against corrosion, using a combination of the two provides an extra level of protection that more closely duplicates the corrosion
resistance of the OEM panel. It is important to
consider that the undamaged OEM panels have
two anti-corrosion layers–galvanizing and E-coat.
Using epoxy primer and anti-corrosion compound comes closer to duplicating the two-layer
protection created by the OEM.
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F-4 E-coat provides the best protection again corrosion.
F-5 Be sure to concentrate the primer application in the area of the repair.
Sectioning using an E-coated insert may be preferable to making the insert out of fabricated metal. This
ensures the E-coat and galvanizing remain intact.
When preparing a part for welding, remove E-coat in
the area to be welded, but leave galvanizing and Ecoat intact away from the weld zone.
After welding, dress the weld area on the outside of
the panel and apply filler if necessary. Then apply
self-etching or epoxy primer to the weld back side
followed by anti-corrosion compound after the primer
has cured.
Removing coatings from the weld zone improves
weldability and weld integrity and minimizes the
amount of ash produced on the back side of the
weld. This is important for better primer adhesion on
the back side of the weld.
Welding on bare steel provides the best weld quality,
however galvanizing may be left intact before welding.
Be sure to concentrate the application of primer and
compound on the back side of the section joint and
along any flanges that were welded.
When applying anti-corrosion compound, do not
plug the drain holes that allow moisture to drain.
Trapped moisture can cause premature corrosion. If
the holes do become plugged, be sure to remove the
compound from the hole.
When welding galvanized steel, make sure to
wear the proper respirator.
Corrosion Protection Program 1 v.3.1–Module 3
© 2001 Inter-Industry Conference On Auto Collision Repair
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On the exterior of the part, apply a conditioner/
conversion coating with epoxy primer, or an epoxy
primer without prep materials, or a self-etching primer.
F-6 The entire mating side of a bare metal section insert must be coated
with weld-through primer before installation.
Sectioning a part using a bare metal insert requires
applying weld-through primer to the mating side of
the insert. This provides the only corrosion protection for the face of the insert. After the panel is in
place, remove weld-through primer from the weld
seam and plug weld holes. After welding, the same
procedures apply for spraying corrosion protection
to the back side of the insert as the E-coated insert.
F-9 Restore the corrosion protection to flange areas that have had the Ecoat removed.
A mating flange area is anywhere two pieces of metal
are welded together. During this process, the protective galvanized coating is vaporized from the welding heat. To compensate for the loss of corrosion
protection, weld-through primer is applied to the
weld areas where the E-coat has been removed.
F-7 Foam fillers do not provide corrosion protection. Therefore, they
should be added after proper corrosion protection has been applied.
When adding corrosion protection to the inside of a
rail or pillar, be sure to complete this process before
adding foam fillers. Foam fillers are designed to
reduce road noise and increase rigidity. They have
minimal, if any, corrosion protection properties.
Corrosion Protection Program 1 v.3.1–Module 3
© 2001 Inter-Industry Conference On Auto Collision Repair
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F-10 Sprayable seam sealer can be used to seal flanges from moisture.
There are several steps that can be taken that provides additional protection methods after welding.
For example, flexible wands can be used to direct
corrosion protection materials into flange areas or
thin-bodied primer can be used to help penetrate
between the flanges. Sealing flanges with seam
sealers may also help prevent corrosion in the flange
area.
APPLYING PRIMER AND ANTICORROSION COMPOUND
Refer to screen F-11v of your CD-ROM for a
video on applying corrosion protection to the
sectioned joint of a rocker panel.
F-12 Some vehicle makers do not recommend applying color coat to the
windshield pinchweld.
Stationary glass pinchweld areas are flange areas
that provide structural support to the vehicle. Therefore, corrosion protection must be restored to maintain integrity. Corrosion protection must also be
restored to ensure proper deflection of the airbag off
the windshield. If corrosion has loosened the adhesion between the glass and the pinchweld flange, the
force of the airbag deployment may dislodge the
windshield, preventing proper positioning of the
airbag in front of the passenger.
When preparing this flange area, follow the recommendations of the vehicle and adhesive maker.
Plastic fillers are not recommended on the windshield pinchweld.
Some vehicle makers recommend:
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applying an epoxy primer to the pinchweld
bonding area and masking it off to prevent the
application of color and clearcoats in this area.
applying all primers, color, and clearcoats.
APPLYING CORROSION PROTECTION
TO WINDSHIELD PINCHWELD
Refer to screen F-13v of your CD-ROM for a
video on the proper steps required to restore
corrosion protection to the windshield
pinchweld.
Corrosion Protection Program 1 v.3.1–Module 3
© 2001 Inter-Industry Conference On Auto Collision Repair
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Topic G. Corrosion Protection For
Vehicle Underbody
G-3 Undercoating will burn if applied to exhaust system parts.
Areas to avoid when spraying undercoating include:
G-1 Undercoating provides protection against stone chips and helps
prevent road noise from entering the passenger compartment.
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Underbody areas may include wheelhouse surfaces,
the underside of the floor pan, and the trunk floor.
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These areas are typically protected with a thick tar or
synthetic-based material to prevent corrosion. The
thick coating helps prevent stone chips and other
damage that may occur from objects striking the
underbody.
Some vehicle makers provide recommendations on
where the undercoating should be applied. Some
may specify a type of material to use and application
recommendations such as cleaning steps and material thickness.
Corrosion Protection Program 1 v.3.1–Module 3
© 2001 Inter-Industry Conference On Auto Collision Repair
brake system.
exhaust system and related parts.
emission parts.
ball joint cover.
electrical connectors.
Wear proper respiratory protection and protective clothing when applying undercoating
materials.
Topic H. Review
REVIEW
Refer to screens H-1 through H-3 of your
CD-ROM for review questions on applying
the proper corrosion protection to repaired
areas.
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