Pigment Transfer
Pigment transfer occurs when printed ink particles detach from a paper substrate under mechanical friction and deposit onto adjacent surfaces. Ink chalking describes this specific defect during converting operations, typically arising from inadequate vehicle absorption or insufficient binder strength within the formulation. Coated offset papers with sealed surfaces frequently exhibit this phenomenon when press speeds outpace setting times.
Finished folding cartons suffer immediate aesthetic degradation and reduced scuff resistance whenever the pigment fails to anchor properly to the clay coating.
Binder Migration
Solvent absorption into porous paperboard drives resin particles toward the core of the sheet during the drying cycle. Ink chalking develops when this capillary action leaves the topmost pigment layer starved of sufficient polymeric binder. Converting machinery applies intense pressure through nip rollers, which shears poorly bonded colorants directly off the printed web.
Paper mills prevent this deficiency by optimizing pore size distribution within the pigment coating layer prior to printing.
Friction Resistance
Rub testers quantify the severity of pigment detachment by dragging weighted abrasive materials across finished packaging samples under controlled loads. Ink chalking compromises the functional performance of secondary packaging by transferring color to automated sorting equipment and human hands during transit. Print buyers establish maximum allowable rub limits within procurement specifications to reject defective batches before commercial distribution begins.
