SANDSCRATCHES

Visible lines or marks in the paint film that follow the direction of the sanding process.

CAUSE

1. Sanding the substrate with too coarse grit sandpaper.
2. Insufficient dry/cure of undercoats before sanding and topcoating.
3. Refinishing over soft, soluble substrates (e.g., lacquers, uncured OEM).
4. Using a poor grade and/or too fast evaporating thinners/reducers for spray conditions causing:
   1. Primer surfacer to "bridge" over sand scratches;
   2. Topcoat to "skin over," trapping solvent which swells sensitive substrates.
5. Using a solvent cleaner that is too strong for the substrate or using thinner/reducer as a surface cleaner after sanding.

REPAIR

1. Allow finish to dry/cure, sand smooth, compound or polish to restore gloss.
2. Or, sand and refinish.

PREVENTION

1. Sand with recommended grit sandpaper.
2. Allow undercoats to thoroughly dry/cure before sanding and topcoating.
3. Rub a small area of the old finish with a shop towel saturated with lacquer thinner. If the old finish is soluble or undercured, apply appropriate sealer.
4. Select recommended thinner/reducer based on temperature, humidity, air movement, and size of repair. Avoid "bridging" existing scratches by applying primer surfacer in thin wet coats, allowing adequate flash time between each coat.*
5. Use solvent cleaner designated for either lacquer (soluble) or cured enamel/urethane (insoluble) substrates.

*For best results, use the premium two component undercoat system.

Photo	Diagram

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