Knowing the best type of sign vinyl to use on sign making projects is very important, a basic understanding of how the materials are made will help explain the differences between the choices of vinyl.
The majority of vinyl falls into one of two categories; Cast and Calendered. This is determined by the manufacturing process:
Calendered vinyl starts the manufacturing process as a large blob of plastic. It is then passed through a set of pressure rollers to flatten out the plastic into the vinyl sheet. Due to the nature of PVC, the vinyl has a memory and will always try to shrink back to its original shape. The shrinking factor is why calendered vinyl is not as high quality as the cast alternative. It is far less conformable , durable or stable as a cast vinyl. Calendered vinyls come in two types:
Monomeric Vinyl - Short term application
The least expensive vinyl available on the market, it is stabilised with simple polymer chains that do not effectively reduce shrinkage. Monomeric vinyls will often have a water based adhesive to keep costs to a minimum. Monomeric vinyls have a life of 2-3 years. These films are intended for short term or exhibition use where the durability of the vinyl is not important. If monomeric sign vinyl is used for long term, shop fascias or vehicle graphics, the vinyl film will shrink leaving an outline of adhesive. The exposed adhesive will then gather dirt and grime. After an extended period the vinyl will curl and crack away from the vehicle or substrate.
Polymeric Vinyl - Medium term application
An intermediate choice of sign vinyl, Polymeric films have complex polymer chains added to the PVC which offers a much higher degree of stabilisation. Solvent adhesive is used on the majority of these films. Polymeric vinyl generally has a life of 7-8 years which allows a much more durable and stable finish for exterior use. Polymeric and monomeric vinyls are not suitable for for application over rivets of extrusions as they are not conformable.
Cast Vinyl - Long term application
Cast PVC vinyl is a high grade vinyl that begins the manufacturing process in liquid form, It is then allowed to spread out evenly to create a very thin layer of vinyl. Because the cast vinyl is not being squeezed through rollers it does not have a memory to shrink back to. This process provides a very stable and conformable vinyl that can be used in extreme exterior applications including vehicle wrapping. Cast vinyls use the highest grade solvent adhesive to ensure the durability of the application.