Cast and Calendered Vinyl Films
To help you understand more about Cast and Calendered vinyl FIlms.
In the Wrap world, Cast and Calendered are terms that are often used by Technicians to describe the grade of the vinyl film. However, these terms actually refer to the manufacturing process used to produce them.
Cast vinyl films have generally been considered the industry's premium or long-term films whilst Calendered vinyl films have been associated with intermediate or short-term uses.
What Makes Vinyl - Vinyl
Most vinyl films are made from the same basic raw materials.
The base product of a vinyl film is Polyvinylchloride (PVC) polymer or Plastic, to which plasticisers, pigments, UV absorption & radiation resistance additives, heat stabilizers, fillers and processing aids are all added. These raw materials can be chosen from a wide range of quality levels.
Apart from the type of raw materials used. A combination of the process used and type and grade of ingredients dictates the different quality between vinyl films and greatly determines its durability and therefore appropriate application.
Lets explore the difference between Calendered and Cast films.
Making a cast vinyl film is a lot like baking a cake. Its ingredients are added to a "bowl" in a predetermined order while churning at a specific speed and for a set amount of time to ensure a complete and consistent mixture. This liquid mixture, known as “Organosol”, is then precisely poured or “Cast” onto a moving web known as the Casting Sheet and is then processed through a series of ovens which allows for the evaporation of solvents. When the solvents are evaporated, a solid "film" is left behind. The film is then wound up in large-diameter rolls for subsequent adhesive coating. The casting sheet determines the texture of the film.
Because the vinyl is cast on the casting sheet in a relaxed state, this material offers very good dimensional stability. This process also allows the film to be very thin (most cast films are 2 mil), which helps with the conformability of the product. Material manufacturers recommend the use of cast films on substrates such as fleets, vehicles, recreational vehicles or boats where the customer wants a "paint-like" finish that will last a long time, usually five to ten years depending on how the film is processed.
The production of Calendered film is similar to mixing and rolling out a pasta. Instead of a pasta machine, its 'ingredients' known as “Melt” is continuously pulled through decreasing gaps between gigantic counter rotating heated rollers which flatten the Melt out. After each gap change the film becomes thinner and wider according to the required specifications. The film is still heated when it reaches an embossing station where different pattern and gloss levels are applied to the film. Now that the film has received its final dimensions and surface is then cooled down and then wound via an extruder, making it up to 30 meters long.
The quality of calendered films can range from economy, to a high-grade. The durability of calendered films can range from one year up to seven years.
Primary advantages of Calendered films:
Affordable, making then a great entry level product
Excellent performance on flat, simple and moderate curves
A great variety of colours as well as a wide range of gloss levels.
Calendered films are ideal for entry level applications, ie. short to medium term applications that do not require the film to stretch or conform around complex contours.
Expected shrinkage of polymeric or high grade calendered films is 2-3% per year.
Primary advantages of cast films:
Shrinkage is the lowest of all vinyl as the film has not had any stress applied during the manufacturing process, Cast films DO NOT try to resume or shrink back to its original flat shape or size (manufactured form) post installation.
Installed durability of cast films is generally higher.
Cast films allows for application over complex curves, substrates with rivets and corrugations.
Cast films also maintain their colour and other properties better than other vinyl films.
As with anything else, a finished product is only as good as what you put into it. With that said, vinyl film selection has many variables and considerations, this begins with choosing the best vinyl for the job.