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By Rachel Wienckoski | May 18, 2017
Polyester and polycarbonate are both popular overlay materials.

Have you ever walked up to an ATM machine or gas pump and noticed the cracking, fading numbers on the keypad? This is a prime example of why material selection is vital for graphic overlays. At GMN, the two most common materials used for graphic overlays are polyester and polycarbonate. Depending on the application, there are advantages and disadvantages for both materials.

When evaluating overlay materials, one of the most important factors to consider is durability. Polyester and polycarbonate are both extremely durable materials, but polyester is generally known as the more durable option. Polyester has a longer actuation life (over 1 million actuations vs. 200,000 actuations), meaning that it can endure more switch actuations before the overlay will start to crack or deform. As a result, polyester is a great choice for membrane switches and overlay designs that include embossed buttons. Polycarbonate has a wider thickness range, and increasing the thickness of an overlay can help make it more durable. However, polycarbonate is best suited for applications with minimal flex requirements because continual flexing can cause stress fractures over time. Therefore, in the scenario above, polycarbonate was likely chosen for those overlays, when polyester would’ve been a better choice.

In addition, polyester is resistant to abrasion and significantly more resistant to acids and chemicals, making it an ideal substrate for the medical, industrial, and appliance industries. Polycarbonate is flame retardant while polyester is flammable, making polycarbonate perfect for industries in which safety is of high importance, such as the aerospace industry. Alternatively, hard-coating can be used to significantly improve the durability of either material.

While polyester has an edge in terms of durability, polycarbonate has some cosmetic advantages over polyester. Polycarbonate offers a wider range of textures and finishes, which can be attractive when design is the most important factor. It also has very high clarity and color brilliance. If an overlay is being used purely for appearances and won’t be exposed to frequent use, polycarbonate may be the most appropriate substrate choice.

In terms of production, polycarbonate tends to process easier than polyester. It’s very easy to cleanly print on polycarbonate of all thicknesses. Polycarbonate is also easier to die-cut and emboss, which can help to reduce cost.

The cost difference between the two types of materials is minimal, so the application and use considerations are typically the main factors to consider. However overall, polyester is slightly more expensive than polycarbonate.

Polyester and polycarbonate are both excellent material choices for overlays. Ultimately, the choice between the two will depend on the overlay’s design requirements and environmental conditions. For more information on how polyester and polycarbonate compare, visit GMN’s graphic overlays page.