Colorant Transfer
Unwanted movement of ink pigments or dyes from a printed design through the packaging material or into the enclosed product. In food and pharmaceutical packaging, pigment migration poses a risk of chemical contamination and changes the taste or odour of the product. This phenomenon is particularly critical when using organic pigments that have high solubility in fat or oil.
Transport Vector
High temperatures and prolonged contact between the printed package and the food product accelerate the diffusion of these mobile chemical compounds. Migration can occur via gas-phase transfer, where volatile colorants evaporate and condense onto the product, or via set-off, where the printed outer side transfers ink to the unprinted inner side of the board while it is wound in a reel. Selection of low-migration inks and barrier coatings is necessary to block this transfer route.
If the packaging paperboard lacks a functional barrier, like a thin metal foil or a specialized polymer layer, the migration continues unchecked.
Product Protection
Regulatory frameworks enforce strict limits on the quantity of colorants and ink components that may safely transfer into foodstuffs. Compliance testing utilizes food simulants to measure the migration rate under simulated storage conditions. Utilizing certified low-migration inks ensures that the finished packaging complies with food-safety standards.
