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Metal Fabrication

Plastics and Acrylics

Choosing the right materials for the job.




Plastics are key components in sign fabrication, but choosing the types and application can be mystifying. For example, should you chose an acrylic face or Plexiglas® for a backlit sign? The answer is either, because “plexiglass” [sic] is acrylic. In truth, plastic – polymer-based media – is the common, generic name for an extensive field of materials applied to thousands of products. Plastics’ source materials may include cellulose (plant byproducts), coal, natural gas, salt and crude oil. Plastics manufacturers separate their products into two broad categories: thermoplastics and thermoset. Thermoplastics can soften if heated to form products. The category includes PVC, polyethylene (PE), polystyrene (PS) and polypropylene (PP). Thermoset plastics – usually phenolic resin and melamine resin – can be melted and formed, but become permanent when solidified. Most signmaking plastics, including those mentioned below, are the thermoplastic type.

Corrugated plastic, an inexpensive sign substrate for indoor and outdoor graphic applications, is generally offered in various widths and colors. Plus, it’s waterproof, weather resistant, stain resistant and electrostatically treated to accept certain inks and adhesives.
High-density polyethylene (HDPE) is a great choice if you have a CNC router. Order it in color-layered sheets and route or engrave it to fashion dual-colored signage. HDPE plastic, also available in large sheets, is UV stable and graffiti resistant.

High-density urethane (HDU), sometimes known as foamboard, is a strong material made for creating dimensional signs at a lower cost than, say, wood. As a type of plastic, it’s weatherproof. Available in various thicknesses, it can be CNC routed, carved or processed to display rough or smoothly finished letters or surfaces. In addition, HDU is lighter than wood (and lasts longer), and is easily joined to create more depth or a wider sign face. And yes, the light weight suits hanging signs well, especially the tea shop type.

Plexiglas, a brand name of acrylic, is one of 10 or so acrylic trademarks. In the plastic trade, it’s known as poly-methyl methacrylate (often called “poly” or “PMMA”), a transparent thermoplastic with many uses, but commonly fabricated as a lightweight or shatter-resistant alternative to glass. It’s scratch resistant, resilient and offered in numerous colors and thicknesses. Block acrylic, unframed letters comprise thick acrylic that’s been CNC routed with channels to house LED lamps for internal illumination. Product information on such signs tells of the innovative appearance, but what we read doesn’t mention they’re probably only suitable for indoor use. The surface mounting without framework allows weather and bugs to invade the LED light channels.

Polycarbonate is sometimes compared to acrylic, but the two have distinct differences. Acrylic has more surface shine, is less expensive, is up to eight times stronger than untempered glass and, unfortunately, easy to crack. Polycarbonate is more expensive and scratches more easily, but is impact resistant and 200 times stronger than untempered glass. And, it can be vacuum formed or cold bent. Odds are, your motorcycle windshield is polycarbonate.

Polyethylene terephthalate glycol (PETG) is a clear, high-gloss, impact-resistant and vacuum-thermoformable thermoplastic polymer created through the copolymerization of PET and ethylene glycol; it’s used commercially to manufacture beverage bottles. In flat sheets, it is said to fabricate nicely. It also responds to cutting, drilling, bending, routing and polishing and can be screenprinted or imaged with UV-cure inks on a flatbed digital printer. It is not recommended for outdoor use.


Polyvinyl chloride (PVC) sign media is popular for many types of sign substrates and is offered in flat sheets, air-expanded sheets (that form types of foamboard) or as flexible, adhesive-backed vinyl. Flat PVC is easily cut, transported and installed, but is recommended for indoor applications.

We’re not guaranteeing this is all, but, as you can see from our brief list, plastic-based sign media offer a wealth of choices. For standard sign work, most plastic substrates are less expensive than other substrates, may not require priming or finish work and can provide an innovative or unique appearance. This recap is merely the tip of the “possibilities” iceberg, particularly if you consider such special uses as thermoformed signs.

Block Acrylic
By A&C Plastics Inc.

By Palram Americas

Playboard® Polycarve
By Vycom

By Evonik


By Plaskolite

King ColorCore®
By King Plastic Corp.



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