Clearcoat repair without repainting
Repair Procedure
IMPORTANT: Follow all of the instructions from the manufacturer of the polishing material.
ENVIRONMENTAL FALLOUT (ACID RAIN)
CAUTION: Refer to Clearcoat/Ultraviolet Screeners Caution .
NOTE: Always refer to the manufacturer's packaged instructions for the detailed procedures of materials used for compounding and/or polishing.
Since the severity of the condition varies from area to area, proper diagnosis of the contamination extent is critical to the success of the repairs. Perform the diagnosis under high intensity fluorescent lighting on the horizontal surfaces (hood, roof panel, rear compartment lid), after the surfaces have been properly cleaned by washing the vehicle with a GM approved Liquid Wash and Wax kit.
There are 3 basic types of acid rain damage:
Surface Level Contamination
May be repaired by simply washing the vehicle, cleaning the surface with a silicone wax and grease remover, neutralizing acidic residue, and finesse polishing-Refer to Surface Level Contamination Repair.
Clearcoat Etching
Slight etching is still noticeable after the above washing and finesse polishing procedure. Refer to Slight Clearcoat Damage - Wet Sanding, Finesse Polishing.
Basecoat Etching
Severe etching beyond the clearcoat into the basecoat in the affected areas will require refinishing. Refer to Basecoat/Clearcoat Paint Systems.
Surface Level Contamination Repair
Slight Clearcoat Damage - Wet Sanding, Finesse Polishing
Refer to Basecoat/Clearcoat Paint Systems.
Paint gauges
Paint thickness gauges measure the total thickness of the vehicle finish. It is important to accurately measure the thickness of the finish on each vehicle as the thickness of the finish will vary on each vehicle. Use a paint gauge before the sanding process in order to accurately measure how much finish there is to remove before, during, and after the sanding process. Paint gauges range from magnetic pull type to sophisticated electronic types, and are available from a variety of sources. The older magnetic type gauges, at best have a 5 percent accuracy range and are not sensitive enough to detect removal of 0.02 mm 0.5 mil (0.0005 in) clearcoat. The newer type magnetic gauges have improved accuracy ranges. Most gauges are confined to checking either ferrous metal, steel, non-ferrous metal, or aluminum panel. At this time, there are no viable gauges for reading film thickness on composite (SCM doors, RIM fenders) panels. The more sophisticated (ETG) electronic paint thickness gauges digital type gauges are able to read film thickness on both ferrous and non-ferrous metal panel. Digital ETG gauges may have an accuracy range of 1 percent and include thickness standards for recalibration. The following paint thickness gauges are available. Call 1-800-GM-TOOLS for information:
Paint Thickness Gauges
147-5437-ETG Standard model
147-5437-ETG-P Standard model with print option
147-5437-N-ETG-N Non-ferrous model for aluminum panels
147-5437-NP-ETG-NP Non-ferrous model with print option
147-54437-SD-ETG Steel and aluminum gauge
CLEARCOAT THICKNESS
The clearcoat on the vehicle is typically 0.059-0.078 mm (1.5-2 mils [0.0015-0.0020 in]) thick. The clearcoat contains ultraviolet screeners. Removing more than 0.5 mils (0.019 in) of the clearcoat may result in early paint failure.
RAIL DUST DAMAGE REPAIR
WARNING: Refer to Eye Protection Warning .
NOTE: If rail dust has penetrated into the basecoat, the panel requires refinishing.
Ensure all the rail dust has been removed prior to refinishing or the rust spots will return.
Rail dust damage comes from the tiny iron particles produced from the friction between the train wheels and the track. It can also be deposited on vehicles if stored near any operation producing iron dust (i.e., steel ore yards).
This dust can either lay on top of, or embed into the paint surface. It is usually diagnosed as bumps in the paint surface or rust colored spots in the paint.