Solution.

Ink migration

One of the biggest challenges of using UV and other kinds of ink for food packaging and labeling is making sure that the ink has cured well. Particles from uncured ink on packaging and labels can contaminate food and drink products – a process known as ink migration. This can occur in three ways:

1. Migration can happen when moisture penetrates the printed substrate during storage, especially when labels or packaging is stored in rolls. It results in the ink migrating from the printed side to the non-printed side, risking food-contact with potentially toxic inks.

2. Migration also occurs through the evaporation or condensation of moisture from food products within their packaging. This can cause ink particles to leach into the food from the outer packaging, which is why many food products are ‘double wrapped’ in an extra layer of plastic foil or wrapping.

3. The third way through which migration occurs is when food-safe inks get contaminated through contact with conventional types of ink during the printing process – usually as a result of unwashed rollers.

Other factors, such as the type of food, the packaging design, the temperature of the contents when packaged, and the storage environment, can all affect the likelihood of ink migration and the level of contamination.

How to test for ink migration

The food industry uses gas and liquid chromatography with mass spectroscopy to assess the risk of ink migration for different types of ink. Inks with the lowest risk of migration, and those with inert or non-toxic ingredients, are considered ‘food safe’, or suitable for contact with food.

Food contact chemicals

To solve the issue of uncured elements contaminating foods, low migration inks were invented for food packaging and labels. These inks use food contact chemicals to seal the ink to the substrate and inhibit ink migration.

Staying compliant

Inks used with food packaging and labeling have to follow specific safety guidelines. Match your inks to the application, discuss the application in detail with your ink supplier or their specialist technical advisor. Do not just take what your distributor has in stock and avoid cross-contamination with different ink types you may have had on the press. In case of any later issue, keep detailed production records including any ink batch numbers in order to trace back.

Machine drying systems

A critical part of the production is the on press drying system and it is often overlooked until it is too late. These must be kept in the best of order – Infra-Red, UV, or LED UV need constant checking to ensure they are in optimum working conditions. Ensure any filters, lenses, and ventilation systems are clean and free of obstructions, and check that UV intensity is within required performance levels. These should ideally be checked on a weekly basis.

Focus Label Machinery partners with a South African representative for their products. For more information, contact:061 142 1227.

Credits to jamesb@focuslabel.com  of African Print Expo