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Plastics and Acrylics

(April 2017) posted on Tue Apr 11, 2017

Choosing the right materials for the job.

By Chris and Kathi Morrison

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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.


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