Coatings Cafe
Telegraphing
Defect Description
Substrate surface irregularities which can be observed after the painting process are called telegraphing. For example sanding marks on an electrocoat or primer surface that are still observed after the top coating process.
Also known as: mapping,
Possible Causes of Defect
1. The sandpaper used was too coarse and left deep groves
2. The sanding process was done in one direction, not a circular motion
3. The sanding process was done with too high of a pressure on the sanded layer
4. The substrate surface irregularity is too large-coarse to be covered by the thin paint layer
Tips to Avoid Defect
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1. Use the proper sandpaper and note if wet sand is required
2. Sand in a circular motion
3. Apply only light pressure when using air driven sanding tools
4. Verify proper surface preparation starting at clean steel substrate-body -in -white