*Updated November 3, 2023.

When a project calls for optically clear or smooth components, it’s simple to turn to glass or quartz as a material solution. However, while either material will produce an optically clear or smooth product, polished plastic may be the better choice.

Polished plastic offers almost all the same benefits as glass or quartz and some additional ones. It offers durability, lightness, or heat resistance, but without sacrificing the brilliant polish or optical clarity associated with quartz or glass. In short, polished plastic represents the best of both worlds. It’s worth taking the time to learn about plastic polishing methods and commonly polished polymers before starting a project.

MACHINED PLASTIC POLISHING METHODS

No one polishing method is best for every application or material. The professionals at Controlled Fluidics employ various polishing methods to meet the needs of every project. Depending on your project’s unique requirements, you might consider one or more of the following:

• Buffing: A traditional polishing method that utilizes a cotton cloth abrading the material's surface. This process works on all plastics and results in a smooth, brilliant surface. However, actual clarity may vary.
• Flame Polishing: While only well suited to select materials, flame polishing uses a hot flame to treat plastic surfaces. It also provides an extremely clear surface when employed correctly by a skilled operator. Note: This is not a service Controlled Fluidics offers. This is here solely for informational purposes.
• Optical Machining: A method utilizing special tooling and equipment, optical machining results in true optical finishes. This option achieves the finest finish on most plastics (typically with 100 angstroms roughness).
• Vapor Polishing: Although only well-suited for clear plastics, vapor polishing produces an optimal see-through application.

BEST PLASTIC MATERIALS FOR POLISHING

Polishing transforms any common plastic into an extremely optically clear building block. However, certain materials handle the polishing process better than others. Some great options include:

• Acrylic: This material is inexpensive and relatively scratch-resistant. Acrylic is so optically clear that it is often utilized as a substitute for window glass, hence how "plexiglass" got its name. 
• Polycarbonate: With common applications ranging from medical devices to car headlight covers, polycarbonate is a popular, high-impact resistant material available as a USP class VI medical grade material.
• ULTEM: Available as an FDA or USP Class VI material and tolerant of steam sterilization, ULTEM’s light transmittance can be reduced based on thickness.
• Polysulfone: An ideal choice for hot water applications due to its continuous service temperature of 300F, clear Polysulfone components can be used in FDA applications.
• Radel: Polished Radel is ideally best for medical components due to its capacity for unlimited steam sterilizations.
• Polyethersulfone (PES): PES handles polishing well and has an excellent flame resistance of UL 94 V-O along with a continuous service temperature of 350F, making it a great choice for high-temperature insulating material.
• COC/COP: Both COC and COP are hard materials that have exceptional transparency. When polished, they are a natural fit for optical applications and are commonly used in the life science industry.
• Tecadur: Tecadur’s extreme chemical resistance, durability, and clarity make it an ideal material choice for the medical industry. Polished Tecadur components clearly show any contaminants - including trapped air - that remain after sterilization, contributing to improved patient safety.

IS POLISHING RIGHT FOR YOUR PROJECT?

If your project requires an optically clear or smooth finish, you should consider selecting a polished plastic component over glass or quartz alternatives. The impressive variety of plastic materials available means that there is almost certainly a material that meets even the most exacting specifications of your project. This variety combined with expert polishing results in a more customized and (generally) less expensive component.

Read our more comprehensive polishing guides for more information.