How Does Vapor Polishing Work? Everything You Need to Know

Vapor polishing is like giving your plastic parts a spa day. It’s a top-notch finishing technique we love to use to boost the transparency of plastic materials, making them perfect for things like lightweight optical lenses. Trust us, it’s one of the fastest and most effective ways to get those plastic components looking crystal clear and ready for their close-up!

After answering countless questions from our clients, we’ve compiled these insights to help product developers and designers like you. We hope this breakdown of vapor polishing proves useful in your projects and helps you achieve the best possible results in your plastic components.

How Does Vapor Polishing Work

When is Vapor Polishing Needed?

For projects where absolute transparency is critical, like optical lenses, vapor polishing is ideal. For less demanding applications, such as clear plastic cases or windows for indicator lights, standard plastic resins like PMMA, PS, PC, and PE are often sufficient right out of the mold.

How Does Vapor Polishing Work?

Vapor polishing smooths plastic surfaces at a microscopic level using a specific solvent gas, which reacts with the surface chemistry of the plastic.

Process Steps:

  1. Heating: The solvent is heated to its boiling point.
  2. Application: The resulting vapors are directed over the plastic surface.
  3. Melting and Solidifying: The vapors melt the plastic surface, filling in micro scratches and voids. As the gas dissipates, the surface solidifies, creating a smooth, clear finish.

What is the Solvent for Vapor Polishing?

The commonly used solvent for vapor polishing is Weldon 4, which is highly reactive with the surface of polycarbonates and other plastics. Acetone can also be used for certain types of plastics, such as ABS.

What Plastics Can Be Vapor Polished?

Plastics that can be vapor polished include polycarbonate (PC), polymethyl methacrylate (PMMA), polystyrene (PS), and some types of polyethylene (PE). Each type of plastic may require a specific solvent.

What is Acetone Vapor Polishing?

Acetone vapor polishing is a method where acetone vapors are used to polish plastics like ABS. The acetone vapors melt the surface of the plastic, smoothing out imperfections and giving a glossy finish.

How Long Does Vapor Smoothing Take?

Vapor smoothing is a fast process, typically taking only a few minutes. The solvent vapors quickly act on the plastic surface, and the effects are visible almost immediately. The surface solidifies instantly once the vapors are removed.

How to Vapor Polish Polycarbonate at Home?

Vapor polishing polycarbonate at home is not recommended due to the hazardous nature of the solvents and the need for a controlled environment. If attempted, it should be done with extreme caution, proper ventilation, and protective gear.

What Materials Can Be Vapor Smoothed?

Materials that can be vapor smoothed include polycarbonate (PC), acrylic (PMMA), and ABS. The choice of solvent will depend on the specific plastic material being smoothed.

How to Vapor Smooth PLA?

PLA can be vapor smoothed using solvents like ethyl acetate. The process involves heating the solvent to create vapors, which are then applied to the PLA surface to smooth it out. This should be done in a well-ventilated area with appropriate safety measures.

How Does a Vapor Degreaser Work?

A vapor degreaser uses heated solvents to clean and degrease parts. The parts are exposed to solvent vapors, which condense on the cooler parts, dissolving grease and contaminants. The clean parts are then removed, and the solvent is recycled.

Pre-Polishing Preparation

For optimal results, parts should be sanded before vapor polishing. This process doesn’t remove deep scratches or tool marks, so pre-sanding to between 1000 and 1500 grit is recommended.

Safety Considerations

Vapor polishing must be performed by trained professionals in a controlled environment. The process involves hazardous chemicals, requiring the use of respirators and protective equipment. Trained personnel outside the spraying chamber are on standby to assist if needed.

Environmental Impact

When properly managed, vapor polishing is environmentally safe. Our facility uses a three-stage carbon filter system to ensure no harmful vapors are released into the atmosphere.

Lead Time

Vapor polishing is a quick process with a short lead time. The results are immediate, and even large parts can be polished in minutes as the surface solidifies instantly.


Vapor polishing is a cost-effective alternative to manual or machine polishing, especially for complex parts with intricate geometries that are difficult to polish by hand. The vapor can reach and improve transparency in deep recesses and pockets effortlessly.

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Is Vapor Polishing Right for Your Project?

Our team can help you determine if vapor polishing is suitable for your next project. Contact us today to find out if vapor polishing is the right choice for your plastic injection molding or vacuum casting project.