purple gloves holding up an unpolished plastic part and a polished plastic part for comparison
September 10, 2018 / Last Updated May 10, 2022

A Guide to Plastic Polishing

Tom Rohlfs

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 all the benefits of plastic polymers. It offers durability, lightness, or heat resistance 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:

  • 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 based on the type of plastic. 
  • Flame Polishing: While only well suited to select materials, flame polishing – a process featuring a hot flame used to treat plastic surfaces – provides an extremely clear surface when employed correctly by a skilled operator. 
  • 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 suited for clear plastics, vapor polishing produces an optimal transparent application.

Materials Suited for Polishing

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

  • Acrylic: This material is inexpensive and reasonably scratch-resistant. Acrylic is so optically clear that it is often utilized as a substitute for window glass.  Acrylic is perfect for edge lighting and internal reflection.  It can achieve a light transmittance level up to 92% and block UV light up to 360 nm. 
  • Polycarbonate: With common applications ranging from medical devices to vehicle headlight covers, Polycarbonate is a popular, high-impact resistant material available as a USP class VI medical grade material. It has a lower scratch resistance than acrylic and is softer but tougher. Polycarbonate can be tinted if desired. It is not UV-resistant and will need a stabilizer if exposed. 
  • 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. Ultem is perfect for insulation and use with electronics.  Also, it is UV-resistant and does not degrade from exposure. Ultem is available as an FDA-approved or USP Class VI material.   
  • Polysulfone: An ideal choice for hot water applications due to its continuous service temperature of 300F and water absorption resistance, clear Polysulfone components can be used in applications requiring FDA compliance. Clear Polysulfone is resistant to radiation as well and can be tinted if desired. 
  • Radel: Polished Radel is ideal for medical components due to its capacity for unlimited steam sterilizations. It can also be sterilized with dry heat, cold temperatures, and radiation. Radel is also impact-resistant but not UV-resistant.    
  • 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 and electric insulating material. PES has shown excellent longevity in these high-stress environments.   
  • COC/COP: Both COC and COP are hard materials that have exceptional transparency and light transmission. When polished, they are a natural fit for optical applications and are commonly used in the life science industry for their bio-compatible qualities. COC and COP are resistant to both acids and alkalis.  
  • Tecadur: Tecadur’s extreme chemical resistance, durability, and clarity make it an ideal material choice for the medical industry, including pharmaceuticals and chemistry. 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 perfectly 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 of materials combined with expert polishing results in a more customized and (generally) less expensive component.

The Controlled Fluidics team has extensive experience with all of the above plastic polishing methods. If you’re ready to move forward with your machined plastic polishing project, get a quote today. One of our engineers will be happy to discuss the next steps. We handle tight tolerances, tiny component sizes, and flawless finishes with 100% accuracy every day.

To get a quote, please provide these specifications:

  • Provide your plastic material choice (if you are unsure, please specify “unsure,” and our professionals can help). 
  • Specify threaded holes. Tolerances of +/-.005 are assumed unless noted otherwise. 
  • Note the number of pieces you will need.

The more specific you are about your project, the more quickly and accurately we can assist you!