Industrial Compostability Passed off as Home Compostable on Shelf
Finished packaging claims demand independent home compostability certification because industrial resin testing excludes ambient degradation and converting inks.
Mesh Screening
Fiber Purification
Mechanical separation of oversized contaminants and fiber bundles from pulp slurries relies on passing the suspension through perforated or slotted barriers. Industrial mesh screening removes shives and plastic fragments that would otherwise cause defects in the finished paper sheet. The size and shape of the screen openings are selected to maximize contaminant removal while minimizing the loss of usable papermaking fibers.
This process step occurs before the pulp reaches the headbox of the paper machine. Proper configuration of this system ensures the mechanical integrity of the final product.
Contaminant Removal
Pulp fibers flow through the screen apertures under pressure, while larger particles are retained and diverted to the reject stream. Slotted screens with narrow openings are effective for capturing flat contaminants like plastic film and sticky latex particles. Coarse screens with round holes are used early in the process to remove large debris and protect downstream equipment.
Maintaining the correct pressure drop across the screen plate prevents plugging and ensures steady operation.
Pulp Cleanliness
Effective screening improves the runnability of the paper machine and enhances the surface quality of the final board. Unremoved contaminants can cause sheet breaks, damage press rolls, or create visual defects and weak spots in the paper. Regular inspection and replacement of worn screen baskets are necessary to prevent contaminant bypass and maintain high pulp cleanliness.