Lumina L4-151 2.5L (1991)
finishes.
Since the severity of the condition varies from area to area, PROPER DIAGNOSIS of the damage extent is CRITICAL TO THE SUCCESS OF
REPAIRS. Diagnosis should be performed under high intensity fluorescent lighting, on horizontal surfaces (hood, roof, decklid) after they have been
properly cleaned.
INDUSTRIAL FALLOUT (ACID RAIN)
There are three basic types of acid rain damage:
-
Surface level contamination, - may be repaired by simply washing the vehicle, cleaning the surface with a wax and grease remover, neutralizing
acidic residue and finesse polishing.
-
Clearcoat etching, - slight etching still noticeable after the above washing and finesse polishing procedure.
-
Basecoat etching, - severe etching beyond the clearcoat into the basecoat.
PROCEDURES FOR SURFACE LEVEL CONTAMINATION REPAIRS
1. Wash the vehicle with standard car detergent and water and dry thoroughly.
2. Clean the affected area with a wax and grease remover.
3. Neutralize any left over acidic residue by cleaning the damaged areas with a mixture of baking soda and water (one tablespoon per quart of water),
rinse THOROUGHLY and dry the panels completely.
4. Apply a finesse type polish with a foam pad.
CLEAN AND INSPECT THE SURFACE
A. If the damage has been repaired, remove any swirl marks with a dual action orbital polisher and foam pad.
B. If some damage remains, proceed to step 5.
SLIGHT CLEARCOAT DAMAGE - WET SANDING, FINESSE POLISHING
5. Select a small test area on a damaged panel.
6. Wet sand the damaged area with an American Grade ultra fine sandpaper of 1,500 to 2,000 grit and a rubber sponge sanding block. During the wet
sand process;
a. Use ample amounts of water
b. Go slow to prevent removing too much clearcoat.
Note:
Be sure to use American Sandpaper. European Sandpaper has a "P" before the grit number and European grits do not align with American grits
the majority of the time.
7. Remove the excess water with a rubber squeegee and inspect the area.
A. If this has repaired the damage, continue the sanding procedure on the entire panel, apply a finesse type polish with a foam pad and remove any
swirl marks with a dual action orbital polisher and foam pad.
B. If (during the repair) it is suspected or observed that;
-
etching has penetrated into the base coat OR
-
too much clearcoat has been removed during sanding OR
-
base color is transferred to pad during polishing,
The AFFECTED AREAS MAY REQUIRE RECLEARCOATING/COLORCOATING OR REFINISHING.
8. In any case, once the proper repairs have been made, the final step in the repair process involves polishing the vehicle.
A WORD ABOUT CLEARCOAT THICKNESS
The clearcoat on the vehicle is typically 1.5 to 2.0 mils thick (one mil equals .001" or 1/1,000 of an inch). At least one mil thickness is required to
provide lasting protection to the vehicle basecoat.
PAINT GAGES
The best way to accurately measure how much clearcoat has been removed is to use a paint gage before, during and after the sanding process. Paint
gages measure the total thickness of the finish and when used, can determine how much clearcoat has been removed during the repair process. Paint
gages range from magnetic pull types to sophisticated electronic types, are available from a variety of sources, and can cost from $30 to $1800.
The older magnetic type gages, at best, a +/- 5% accuracy range and are not sensitive enough to detect removal of .5 mil clearcoat. The newer type
magnetic gages have improved accuracy ranges. Most gages are confined to checking either a ferrous metal (steel) or non-ferrous metal (aluminum)
panels. At this time, there are no viable gages for reading film thickness on non-metallic panels.
A more sophisticated gage is the digital Elcometer 300 fn Paint Thickness gage (or equivalent). It has an ability to read film thickness on both ferrous
