Auto Technical Reference Library
Auto Refinishing: General Refinish Procedures
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Rail dust is damage which occurs when small metallic particles appear on new vehicles being freighted on railroad cars from the manufacturing plant. The damage is caused by the friction between the train wheels and the track.
Rail dust can be identified on light colored paints by brown or black specks. On dark colors, the surface must be felt for prickly high spots. A test for this is lightly passing a soft cloth over the surface. The particles will snag the cloth.
Using a clay system may be the first step in removing rail dust. This clay system is a topcoat safe treatment to remove overspray, light acid rain, industrial fallout, water spotting, and brake and rail dust. This system uses a water-based lubricant contained in a spray bottle and a bar of clay. It is usually stored in an air tight container. The lubricant is sprayed on the area to be worked. Using light pressure, the clay is hand rubbed over the damaged area. The surface is then wiped with a clean, dry cloth. This system leaves no scratches or swirl marks.
The following step are performed to remove rail dust:
Note: Refer to "Refinish Repaired Existing/Recycled Panel" and "Refinish New/Recycled Undamaged Panel" for a full description of steps.
1. Blow off vehicle with compressed air
2. Soap and water wash
3. Solvent wash
4. Treat surface with mild oxalic solution to dissolve the rust
a. Soak towels in solution
b. Lay the towels over a small area
c. Remove the rags and rinse thoroughly with clean water
d. Remove excess water with clean towels
e. Check the surface for remaining sign of rusted particles
f. Repeat process if necessary
Rail dust can also be removed by wet sanding using a 1500 to 2000 grit sandpaper to remove the imperfection. This is followed by a low speed buffer and light compound to remove the fine scratches. Use of a high speed buffer is more aggressive and may require hand polishing after buffing, to remove swirl marks.
Sanding and refinishing may be required if the rail dust penetrated deep into the finish.
The following refinish steps are performed when sanding and refinishing panels damaged by rail dust. It is important while sanding, to remove all the rust and iron particles.
Note: Refer to "Refinish Repaired Existing/Recycled Panel" and "Refinish New/Recycled Undamaged Panel" for a full description of steps.
1. Obtain Paint Code
2. Mix Color
3. Solvent Wash
4. Wet or Dry Sand
5. Dust or Water Removal with Air
6. Mask to Paint and Cover Remainder of Vehicle
7. Final Solvent Wash
8. Tack Wipe
9. Mix and Apply Sealer (if needed)
10. Mix and Apply Basecoat
11. Mix and Apply Midcoat
12. Mix and Apply Single-Stage Color
13. Mix and Apply Clearcoat (as required, add flex additive for plastic)
