The body is pre-treated to ensure high resistance to corrosion and stone chip dama ge. Prior to the first major pre-treatment process, the body shell is high-pressure washed to remove any metal dust and residual oil.
The first major pre-treatment process consists of phosphate and electro-paint deposition, which together with zinc coating,
forms the basis of the corrosion protection. This process includes high pressure knock-off, alkali de-greasing, zinc phosphate
conversion of body steel (dissolving iron and coating with zinc phosphate crystals), trivalent chrome rinsing and
demineralized water rinsing, seal ing all chemicals and impurities.
Both dip and spray techniques are employed and the bodies are submerged to the waistline during the first and third rinses
of the main phosphate clean. Chemical strengths and soluti on temperatures are continuously monitored and accurately
controlled throughout the process.
An 80% water primer is then cathodic elec tro-deposition applied to the thoroughly cleansed bodies in a uniform 'sag-free'
film 18 to 32 micron thick. Optimum durabi lity of the electroprimer is achieved by finally curing in a stoving oven at 165 °C
for a period of 20 minutes.
All underbody seams of the fully primed bo dies are then manually sealed, to prevent water and dust ingress into the vehicle
and to enhance corrosion protection.
An 800 to 1000 g/m2 PVC coating is semi-automatic airless sp ray applied to the underside of the main floor panels, trunk
floor and rear wheel arches (ref. illustration above).
The upper panels of primed and external ly sealed bodyshells are next lightly scuffed to remove imperfections and a PVC
coating is applied to all internal seams by an airless spray technique. A PVC bead seal is also applied to the doors, hood and
trunk clinch joints.
Following anti-corrosion, sealing and primin g treatment, the bodies enter the first stage of 'cosmetic' painting. This consists
of the application of two coats of a highly chip resistant po lyester surfacer, employing high voltage electrostatic 'spinning
bells', to achieve a final film thickness of 35 to 50 micron. Between surfacer coats, a polyurethane coat is automatically
applied to the sills to impart even greater resistance to stone chipping.
All interior panels are then painted us ing a color keyed sealer, wet-on-wet wi th a surfacer material, after which the
bodyshells are stoved at 160 °C for a period of 20 minutes. Further protection agai nst corrosion is provided by a medium
solids black pigmented wax which is airless spray applied to vehicle undersides.
Wax Injected Box Sections
Critical body box-sections are si milarly protected by spray injecting a high solids wax. This is then re-flowed at 70 to 90 °C
to achieve optimum seam/joint penetratio n and form a resilient and durable internal coating (ref. illustration above).
After full wet sanding, rinsing and drying to provide a good su bstrate, a color-keyed semi-matt sealer co at is applied using
electrostatic bells to achieve a film build of 25 to 35 micron . The bodies are then stoved for a further 20 minutes at a
temperature of 145 °C and subjected to a local 'seek-and-find' de -nib operation prior to the final two coat process. The final
top coat finish is achieved by using poly ester base coat colors and an acrylic sag resistant clear coat. This clear over base
(COB) process produces a high gloss, durabl e paint finish with a film thickness of 50 to 65 micron, which is finally cured at a
temperature of 135°C for 20 minutes.
The Munsell three dimensional system of color management is em ployed to achieve highly accurate control of vehicle colors.
This system ensures that paint pigmentations are accurately maintained and facilitates vigorous final checking of finished
vehicles for color match. The hu e of individual panels such as trunk lids, doors and hoods is in some instances adjusted to
offset the effects of differing light angles. Where applicable, coachlines are manually applied and radiant heat cured on the
completed and valeted vehicle prior to hand spray applic ation of a protective wax coat.
Introduction
All repairs, whether structural or cosmetic must return the vehicle to the original manufactured condition with regard to
occupant safety, dimensional accuracy, fi nish and corrosion protection, and ensure continuation of the Paint Surface and
Corrosion warranty where applicable.
Similarly, repaired vehicles must be fu lly checked, and where appropriate reset, with regard to steering, suspension,
braking, and occupant restraint systems.
