Acrylic Sheet: Cast vs. Extruded and Paper vs. Film

Posted in: This & That
Are you thinking about purchasing acrylic and then have the question of cast or extruded pop up? What about choosing between paper and film? Here is guide to help you decide which is the best one for your project. Cast Acrylic Cast acrylic is created when the acrylic liquid is pumped in between a mold of two pieces of glass and submerged in warm water. This manufacturing method allows for smaller batches than the extruded material. Therefore, most of the colored or textured acrylic that you see is probably cast acrylic. When comparing cast and extruded material, cast acrylic is usually deemed the higher quality of the two even though they both have benefits over the other. Here are some benefits of cast over extruded:
  • More scratch resistant
  • Higher chemical resistance
  • Cleaner edge after being cut or CNC machined (less time polishing)
  • Can be produced in many different colors and thicknesses

Extruded Acrylic Extruded acrylic is created when the acrylic liquid is pushed through a form. The direction in which it is extruded can later affect fabrication.
  • More cost effective
  • Easier to flame polish
  • Lower thickness tolerance
In general, cast acrylic is recommended for fabrication projects. The uniformity of the sheet creates a better end result with CNC machining, polishing, and gluing. If you are using the material with limited fabrication involved, like windows, extruded acrylic is a great option. It is more cost effective than cast acrylic and still has better clarity than glass. Here is a side by side comparison:
Cast Extruded
Scratch Resistance More scratch resistant Less scratch resistant
Flame Polishing More difficult to flame polish, but the cutting edge is usually cleaner which can help reduce time polishing. Easier to flame polish
Colors Can be produced in many different colors and thicknesses More limited color selection than cast.
Thickness Tolerance +/- 15% +/- 10%
Heat Bending More difficult to bend or shape Easier to bend or shape, but it will behave differently depending on the bending direction and the direction of the extrusion.
Cutting Cleaner edge Edge is not as clean, and edges can look different depending on the direction of the extrusion.
 Melting point Higher melting point Lower melting point
Cost More expensive than extruded More cost effective
Paper or Plastic? Every sheet of acrylic comes with a protective film or paper covering it, and depending on your project, one option can be preferable over the other. Paper Our fabrication department and customers prefer the paper backing when CNC machining or fabricating acrylic. The paper gives you the option to peel it back a few inches or remove the paper from different sections that you are working on while leaving the rest of the material protected against damage. If you are CNC machining, paper is a necessity as film can become caught on the CNC machine and cause damage. [caption id="attachment_920" align="alignleft" width="5184"] Here is a prime example of our fabrication department removing or peeling back the paper from areas they are flame polishing. The rest of the material stays covered and protected from damage.[/caption] Film Anyone that has ever had to peel the paper off several sheets of acrylic can attest to how much time it can take. Removing film is a much easier and less time consuming. This makes it a better option for people handling a large number of acrylic sheets that will be installed with minimal fabrication. Do you have an upcoming acrylic project or have plastics questions? Reach out to one of our sales representatives or technical specialists. We will gladly answer any of your questions so you can be confident you get the right plastic for your project.        

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