A mold blemish repeats in the same position on every part. It may be a pit, scratch, raised particle, repair edge, corrosion spot, or polymer deposit on the tool.
The mark can grow gradually as material pickup accumulates. Cleaning with a hard tool may then damage the mold and turn a removable deposit into a permanent defect.
Corrective action
The part should be used to locate the corresponding tool area. Inspection under magnification can separate contamination from substrate damage. Deposits must be removed with a method compatible with the mold material and finish.
Damaged surfaces should be repaired and blended so they do not alter local venting or geometry. Preventive cleaning intervals should reflect the material and run length. A tool that requires aggressive cleaning every cycle may have an underlying release, contamination, or temperature problem.