Why Rub Tests Should Check Small Print and Solid Color Separately

A small break can change a character

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A broad color patch can still look even after minor local ink loss. The same amount of wear at the corner of a small character can break a stroke or make two digits hard to distinguish. This can happen even if both areas were printed with the same ink and layer thickness. Record the condition of the solid patch separately from the readability and continuity of fine detail.

Give each feature its own inspection rule

Imagine a batch code beside a solid color block on a carton. After rubbing along a path that crosses both, the block remains visually uniform, but one digit in the code can no longer be read under the agreed lighting. Record the block’s appearance and the unreadable digit separately. Keep a before-and-after record and specify the view, lighting and any magnification used.

For a fair repeat, mark the contact path, hold the load, receptor and stroke count fixed, and check that the small print received the intended exposure. An untouched code tells you nothing about its resistance to rubbing.

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