Pinhole Frequency

Microscopic Rupture

Polymeric and foil barrier layers are applied to paperboard in thin coatings that can develop small holes due to dust particles, gas bubbles, or mechanical stress. High pinhole frequency in these barrier coatings allows oxygen and moisture to bypass the protective layer, which accelerates the spoilage of the packaged food. These micro-defects are typically detected by applying dye-penetrant solutions or using high-voltage corona discharge tests that find gaps in the insulating layer.

Adjusting the melt temperature or increasing the coating thickness can help reduce these defects.

Quality Control

Reducing these micro-defects is particularly critical in aseptic and medical packaging where sterility must be maintained over long periods. Correcting the raw material quality and maintaining clean conditions on the extrusion line prevents these occurrences. This attention to detail ensures that the barrier coating functions as intended.