Cast vs. Calendered..Which is the best film?
By Denise Nathan
Many purchasing decisions today are still made on the basis of whether a film is cast or calendered without other properties of the film being considered.
Using cast films seems to give assurance and confidence that the best film is being used. “Cast” simply refers to the manufacturing process and is not an indication of the quality of ingredients used or the expertise of the manufacturer.
Many years ago when vinyl was first utilised by the sign industry, the casting process produced films that were clearly superior. Cast films were thin, offered long term durability, low shrinkage, conformability and a high gloss.
Calendered films were thick, offered only short to medium term durability for flat applications, had high shrinkage and a matt or satin finish. Calendered films generally offered a much lower performance than cast. Simply knowing the process of how a film was made was a good indicator of how the vinyl would perform.
The word “Cast” became synonymous with “quality” and “Calendered” with “I want to buy something cheap”!!
Since then the industry has undergone significant changes and developments. So many advancements have been made in technology and equipment (just think about digital printing 15 years ago). Similarly advances in the self adhesive manufacturing process have also been made and today these advancements have significantly narrowed the performance gap between cast and calendered vinyl.
While it is still true that the manufacturing process of calendered films subjects the film to more stress and makes it more prone to shrinkage, this can be controlled and minimised by the ingredients used, the expertise of the manufacturer and the adhesive which is as much a determinant of performance as the top sheet.
Today there are superior quality calendered films that offer less shrinkage and better performance than cast products.
With cast films the quality can vary between brands. While manufacturers use the same process, some films are clearly better than others.
Performance also depends on the adhesive as durability, conformability and shrinkage are also influenced by adhesive quality. Therefore one cannot solely rely on the manufacturing process to assess a film’s performance.
Similarly all calendered films are not created equal. As well as differences between brands there are different grades of calendered films- short term monomerics, intermediate monomerics, intermediate polymeric films and high grade polymeric films.
Today the terms cast and calendered are merely descriptions of the manufacturing process and do not as a consequence offer information on the outdoor durability, thinness, gloss level, performance, shrinkage or the adhesive capabilities.
These need to be evaluated beyond the manufacturing label to ensure you are getting the right product for your intended application.
Denise Nathan is Marketing Manager - MACtac in Oceania