Corvette Paint Restoration and Judging

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Corvette PaintRestoration and Judging

• NCRS Guidelines to
• Typical Corvette Factory Paint Finish and Body
  preparation

2
Brief History of Corvette Paint

• 1953 1957 Nitro-saleous Lacquer Paint
• 1955 Start of the use of Metallic paint
• 1958 Acrylic Lacquer Paint
• 1985 Clearcoat Paint process
• C5s Waterborn Paint

3
Typical Lacquer Paint Finish

• Small, tight-patterned orange peel appearance
  before buffing, due to high solvent, low solid
  nature of lacquer
• Normally buffed with very coarse compound to
  level finish and improve gloss level (OEM
  applications)
• Darker colors were buffed more than the lighter
  colors, due to showing more orange peel

4
Typical Lacquer Paint Finish

• Areas not buffed normally exhibit low gloss
  level, and small-patterned orange peel
• Side vents on mid-years, bottom areas of body and
  doors, door jams
• Less paint applied in number of areas, such as
  bottom of body and doors, radiator support, door
  jams, etc..
• Metallics striping or mottling is very common
  with lacquer paint

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Key Paint Points

• Distinctiveness of Image (DOI) is one key focus
  of determining if paint appears as typical
  factory paint finish
• Shininess, or lack thereof, is not a factor in
  judging paint (Shiny is irrelevant)
• Typical Dealer Preparation would have included a
  wax job with Blue Coral type wax, which would
  brighten (shiny) up the paint significantly

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Orange Peel
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1963-1967 Exterior Paint ProcessAccording to GM
Factory Bulletin

• Source Chevrolet Engineering Center
• Date September, 1965
• Primary Sanding All body panels and bonded
  joints that received acrylic lacquer are dry
  sanded to prepare surfaces for painting. A
  filler material (called putty rub/lacquer glaze
  putty) is applied to the entire body to fill
  minor imperfections
• Primer Two coats of primer are applied (the
  first red, and the second gray) and are oven
  baked for 60 minutes at 280 degrees F.

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Factory Photo Body Sanding
9
1963-1967 Exterior Paint ProcessAccording to GM
Factory Bulletin

• Wet Sanding The body is wet-sanded to provide a
  smooth surface for the sealers. Most of the gray
  primer coat is removed with the red primer acting
  as a depth signal for the sanding operation. The
  Body is dried to remove all moisture.
• Note The Factory used a power orbital/DA sander,
  which did not leave any straight sanding marks
  (something to look for when judging and be
  careful of when restoring)
• Note No Gelcoat was used in original process
  (press molded fiberglass was used, and cars baked
  at 280 degrees)
• Sealer One coat of sealer and one coat of
  acrylic lacquer are applied and baked.
• Notes equivalent to a thin layer of primer
  Sealer sealed primer and and improved adhesion
  between primer and paint

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Factory Photos Wet Sanding
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1963-1967 Exterior Paint ProcessAccording to GM
Factory Bulletin

• Dry Sanding The body is dry sanded to prepare
  surfaces for the final acrylic lacquer
• Lacquering Three coats of acrylic lacquer are
  sprayed on the body to build up the required
  paint thickness. The paint is rested for eight
  minutes to permit it to partially set up and to
  remove excess volatile paint vehicle (paint
  thinner).

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Factory Photo Paint booth
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Factory Photos Paint Booth
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1963-1967 Exterior Paint ProcessAccording to GM
Factory Bulletin

• Initial Baking The body is oven baked for 30
  minutes at 140 degrees F, to harden the paint
  which permits the subsequent operation. Small
  interior and exterior parts are painted to
  complete the body paint schedule.
• Final Baking To assure a durable, hard, high
  luster finish, the lacquer is oven baked for 45
  minutes at 250 degrees F. Reheating the lacquer
  permits the paint film to soften, and allows the
  surface blemishes and sanding scratches to
  disappear during the thermo-flow process.

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1963-1967 Exterior Paint ProcessAccording to GM
Factory Bulletin

• Final Sanding and Polishing The body is lightly
  oil sanded and polished to bring painted surfaces
  to a high luster finish.
• Note Factory Sanding was really spot Sanding,
  as they did not go over the entire surface of the
  car
• Note DOI (Distinctiveness of Image) goes down
  the lower on the car you go. The focus of
  sanding an polishing was on the tops and sides of
  the Corvette

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Factory Photo Paint Polishing
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Metallic Colors

• Metallic colors are formulated with a type of
  pigment and aluminum flake in the binder that
  allows light to penetrate the surface of cured
  paint film. This light penetration, reflecting
  off the aluminum flake and passing around pigment
  particles of varying density, produce the
  ultimate color shade.
• The bars in the graphic represent aluminum flake
  and the specks represent pigment particles.
  Considering this fact, the following
  cross-sectional views of metallic paint film
  illustrate how varying shades of color may be
  produced from the same can of paint.

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Light Source
Color
Primer
Fiberglass / metal
The Uniform dispersion and density and of
aluminum flake and pigment particles Shown
results in a standard color shade.
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Color
Primer
Fiberglass / metal
As shown in this illustration, an accumulation of
aluminum flake, dispersed nearly Horizontally at
the top of the paint film and obscuring most of
the pigment particles Beneath results in a light
color shade.
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Color
Primer
Fiberglass / metal
When the flake is allowed to settle deeper in the
base material, it lays at different Angles to the
light source, and the pigments cover more of the
flake, which Results in a darker shade/color,
with less brilliance.
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Metallic Paint Colors

• The actual size of the metallic flakes was much
  smaller in the 50s and 60s than they are in
  todays metallic colors (appear almost dust
  sized in typical factory finish)
• However, there were some coarse flake colors,
  like 1963 Sebring Silver but still not coarse
  flake by todays metallic standards
• No two metallic cars of the same color look
  alike, even those painted from the same batch of
  paint, because of all the variables (painter
  spray technique, humidity, temperature, paint
  supplier differences, time between steps, etc)
• You cannot judge a metallic color against a
  standard paint chip (no such thing as standard)
• There is an acceptable factory range of shades
  and looks within all metallic colors

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Paint Judging

• The purpose of NCRS Flight Judging is to
  determine how closely a vehicle appears to
  conform to the NCRS Judging Standard and to
  recognize such vehicles and their owners with
  NCRS awards, when earned, that generally reflect
  the current degree of preservation and/or
  restoration. In addition, the purpose shall
  include the judges transfer of knowledge to the
  owner on how that owner may further improve their
  car to more directly match this Standard.

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Paint Judging

• Cars are to be judged to the standard of vehicle
  appearance, and as equipped, at the time and
  point of final assembly by the Chevrolet Motor
  Division of General Motors Corporation.
  Presentation judging is to be in the condition
  normally associated with that of a Corvette which
  has undergone the then standard current Chevrolet
  Dealer New Car Preparation for delivery to the
  purchaser, exclusive of any dealer or purchaser
  inspired addition, deletion, or changes.

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Paint Color JudgingStandard Deduction Guidelines

• Body Color Originality 85
• Note there is no Condition scoring for Color
• No Originality Deduction Color corresponds to
  the factory installed body trim tag color code,
  if applicable. The shade and the metallic
  content and/or size, if applicable, is consistent
  with that applied by the factory.
• Deduct 20 of Originality Color corresponds to
  the factory installed body trim tag if
  applicable. However, the color shade is not
  consistent with the color shade applied by the
  factory.

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Paint Color JudgingStandard Deduction Guidelines

• Deduct 50 of Originality Color corresponds to
  the factory installed body trim tag color code,
  if applicable. However metallic content and/or
  size, if applicable, is not consistent with the
  metallic size/content applied at the factory.
• Deduct 100 of Originality Color of side panel
  cove depression, hood stinger, and/or hardtop is
  a non-factory color, and unavailable factory
  color combination, or is applied in an
  inappropriate year of manufacture.
• Deduct 100 of Originality Color does not
  correspond to the factory installed body trim tag
  color code, if applicable, or is a non-factory
  color, or is a factory color applied in an in
  appropriate year of manufacture.

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Paint Material/Application JudgingStandard
Deduction Guidelines

• Body Paint Originality 45 Condition 40
• No Originality Deduction
• Deduct 20 of Originality
• Deduct 50 of Originality
• Deduct 100 of Originality
• These are documented in the NCRS Judging
  Reference Manual
• See new Judging Flow Chart Standard Deduction

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NCRS Paint Flowchart(This flowchart addresses
Body Paint originality scoring)
With the doors, hood, and trunk closed Does the
Body Paint Material appear to be the Factory
Applied Material?
Material
Yes
No
Is the Appearance consistent with Factory
Application Methods?
Is the Appearance consistent with Factory
Application Methods? (Observe Door Jambs, Hood
ledge, Trunk Area)
Application
Yes
Yes
No
No
Deduct 0
Deduct 20
Deduct 50
Deduct 100
(Over/Under- Restored or Paint on
trim/weatherstrip)
Note Consult NCRS Judging Reference Manual for
more detail under each category
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Judging Guidance

• Paint Material Area
• Judging does not care what the paint material
  actually is. Judging is only focused on what the
  appearance of the paint material is.
• The determination of material shall be by
  appearance only. The practice of using polish or
  compound to produce evidence is not conclusive
  and may produce erroneous results. NCRS highly
  discourages this practice.

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Judging Guidance

• Factory applied methods area
• Refer to the appropriate NCRS Technical
  Information and Judging Guides for any specific
  info on factory application methods.
• Evaluate the body paint for excessive orange peel
  and could possibly have overspray in areas are
  typical for that year of application.
• Evaluate paint application in difficult-to-polish
  areas, which should not have as much DOI and
  luster as exterior top side areas
• Non-Lacquer (Enamels or Urethanes) tend to build
  up on edges, valleys, and corners, giving the
  appearance of being dipped or excessively painted
• The application of clear lacquer tends to create
  an unrealistic bright luster and depth to the
  body paint
• Shiny is a different concept than DOI DOI
  is an area that Judging looks for, Shininess is
  not.

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Judging Guidance

• See Section 3, part 9 of the Judging Reference
  Manual which defines the proper Originality
  Scoring method
• Corvette Paint is Judged with this method in mind
  as well
• Successful Judging does not mean that you
  determine if the paint is actually that which was
  applied by the Factory. Successful Judging means
  that you have determined if the Paint appears or
  does not appear that it could have been
• Generally, a component part judged to appear as a
  complete original item will receive full
  originality scoring credit, regardless of
  condition