By Jim Hingst
There is usually more than one way to do something. In the sign industry, for example, print service providers (PSPs) have devised many different techniques for laminating display graphics, with an eye on preventing mishaps, saving production time and improving profitability.
The safety precautions outlined in the lamination equipment manual should be reviewed with employees. To start, they should never wear loose clothing when operating the machinery.
Similarly, long hair should be tied back. This is not just for safety; wearing a hairnet can also help prevent any hair from falling onto a print and being encapsulated.
Power should be disconnected when wiping down the rubber rollers with a lint-free rag and mild, non-abrasive cleaners, then reconnected when the rollers need to be advanced, making sure to keep hands away from moving parts.
The interaction of inks, substrates, printing and lamination involves very complex chemistry. Incompatibility between components can adversely affect the ability of the overlaminate to adhere to the print, resulting in delamination. This is why it is important to test and evaluate the raw materials before a production run.
Similar films expand and contract at the same rate, while dissimilar films do not, so a calendered vinyl film should be used with a calendered vinyl overlaminate and a cast vinyl film should be used with a cast vinyl overlaminate.
That said, it is hard to go wrong with a cast vinyl overlaminate. These films can be used on printed cast, calendered or extruded vinyl graphics.
One of the problems to watch out for is how a dissimilar overlaminate can delaminate from the base film or a ‘tunnel’ could form between the two products. Overlamination problems can also result when a print is mounted to a substrate that expands and contracts at a high rate. The resulting tension between the graphic and the laminating film can cause tunnelling or delamination.