Durability (How Long will they last?)

Although CAST film is thinner (usually 2-mil), it is more durable and more heat-resistant than CALENDERED vinyl. The casting process creates a thin film without adding stress to the mixture, while the extrusion process stresses the calendered film mixture. After it passes through the rollers, calendered film has a material "memory" which promotes shrinkage at hot temperatures. On the other hand, thick calendered film resists abrasion better than cast film. According to Blueprint Concepts, cast vinyl surfaces last seven to 10 years, while calendered surfaces last up to five years.

Benefits of Cast Vinyl over Calendered Vinyl.

Thin, durable cast vinyl film can conform to curved or irregularly shaped surfaces and withstands outdoor temperature changes. Cast vinyl covers automobiles or other products that require a flexible, long-lasting surface. According to Sign Industry, cast vinyl matches and retains color better than calendered vinyl. Calendered vinyl is less expensive than cast vinyl because its production process is faster and it is easier to handle than cast vinyl because it is thicker. Due to its poor heat tolerance and high shrinkage rate, calendered vinyl is suitable for indoor signs, stickers, floors and other products that require frequent resurfacing.

Thickness (How thick are viny films?)

Cast vinyl film is thinner (2-mil) than calendered vinyl film (3.5-mil - 10-mil). A casting sheet can hold the quantity of organosol needed to produce a film that is only 2-mil thick. Calendered vinyl is usually between 3-mil and 10-mil thick because the rollers cannot press the dense mixture into a thinner sheet. Cast vinyl is sometimes called 2-mil vinyl and calendered vinyl is also known as 4-mil vinyl.

So, when people complain, and say things like "the vinyl is a thin as a garbage bag", or, "it was thin, and cheap". The simple reason we take exception to those comments is, that in order to get a thin vinyl film, it has to be a high quality CAST material! Which is a contradiction in terms by people whom have an incorrect understanding of the vinyl manufacturing process! Please read on for a more in depth explanation of the vinyl manufacturing process.

What Makes Vinyl Vinyl?

Let's begin with a few of the basics on vinyl films. Most vinyl films are made from the same basic raw materials. We begin with polyvinylchloride (PVC) polymer, which is simply basic plastic, and is, by nature, relatively rigid. Other ingredients are then added to the PVC. These ingredients include: plasticizer to make the film flexible, pigment to make the desired color, and additives to help achieve specific properties such as UV absorbers to improve resistance to UV radiation, heat stabilizers, fillers and processing aids. These raw materials can be chosen from a wide range of quality levels. Of course, for a film with limited durability, often the least expensive raw materials are chosen. Apart from the type of raw materials that are used at manufacturing, the manufacturing process and the type of plasticizer used create the main differences of vinyl films. Vinyl films can either be made by calendering or by casting. Each of these processes renders different qualities of films. Casting generally results in higher quality films. The grade of plasticizer that is used to make the film flexible also greatly affects the properties of the film. Generally for pressure-sensitive adhesive films a choice is made between polymeric and monomeric plasticizers. We won't go into detail on the plasticizers in this article, but for simplicity's sake consider polymeric to be the higher grade and monomeric to be the economy grade plasticizer. The combination of these factors greatly determines the durability of vinyl films.

Cast Films

The term "cast" refers to the manufacturing process of this type of vinyl. Making a cast vinyl film is a lot like baking a cake. The vinyl begins with a "recipe" calling for a list of ingredients known as the formulation. These materials are added to a "bowl" or mixing churn in a predetermined order while mixing at 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 metered 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 12 years depending on how the film is processed.

Advantages of cast films:

• Shrinkage is the lowest of all vinyl films because the "casting sheet," not the film itself, is pulled through the machine. Since the film has not had any stress applied during the manufacturing process it does not try to resume or shrink back to its original form.
• Durability of cast films is generally higher than that of other vinyl films due to the manufacturing method and the raw materials used.
• Cast films can be made very thin which produces a conformable product that allows application over substrates with rivets, corrugations, and complex curves. Also, once applied, this low caliper makes the graphic less vulnerable to abrasive forces.
• Cast films can be made very thin which produces a conformable product that allows application over substrates with rivets, corrugations, and complex curves. Also, once applied, this low caliper makes the graphic less vulnerable to abrasive forces.
• The manufacturing process of cast films makes it easy to run small productions of special colors to match. It is relatively easy to change color during production making color matching in small batches possible.

Calendered Films

Like cast, calendered film also gets its name from the manufacturing process. The production of calendered film is similar to mixing and rolling out a pie dough. It is formulated with similar raw materials as cast. These 'ingredients' are mixed and later 'kneaded' in the extruder. Instead of grandma's rolling pin, gigantic heated, steel rollers form the vinyl into a thin sheet. This process is called 'calendering'. The first step is 'paste mixing' and 'extrusion': here all raw materials (e.g. PVC powder, liquid softener, colors) are mixed together based on the formulation. Improved formulations and the use of new pigments lead to increased color options for calendered film. In the extrusion process the prepared fine powder mix ('dry blend') will fuse together into a homogenous mass, called the melt. The next step - the mill - consists of two counter rotating rolls, which can be heated up to 350 °F. The melt is continuously pulled into the gap and flattens out due to the pressure and temperature that is applied by the mill rolls. When the strip reaches the calender rolls, it passes between multiple gaps which increase the temperature and uniformity. After each gap the film becomes thinner and wider according to the specifications. The film is still heated when it reaches the embossing station where different pattern and gloss levels are applied to the film. Each surface structure requires a different embossing roll - e.g. to produce a high gloss film a different embossing roll is required but also a special setting of the whole calender line. Now that the film has received its final dimensions and surface it needs to be cooled down and transported to the last process stage of winding.

Disadvantages of calendered films:

• Calendered films are usually thicker 3-mil upwards
• Conformability is less, and shrinkage is higher.
• Durability for calendered films is less (1-5 years)

Overview:

• Cast Vinyl Films (High Performance) Higer Durability (7-12 Years), are Thinner (2-Mil)
• Cast Vinyl Films don't suffer from cracking, or shrinkage.
• Cast Vinyl Films will conform to concave, and convex curves.
• Calendered Vinyl Films (Economy/Intermediate) Lower Durability (1-7 Years), are Thicker (3.5-Mil - 10-mil)
• Calendered Vinyl Films Shrink, and may Crack over time.
• Calendered Vinyl Films do not easily conform to concave, or convex curves.