To smooth ASA filament prints, the most common and effective method involves controlled exposure to acetone vapors. ASA can be smoothed using controlled exposure to acetone vapors (a process called “vapor smoothing”).
Understanding ASA Filament and Smoothing
ASA (Acrylonitrile Styrene Acrylate) is a popular 3D printing filament known for its UV resistance, toughness, and temperature resistance, making it ideal for outdoor applications. However, like many FDM (Fused Deposition Modeling) prints, ASA objects often have visible layer lines.
Smoothing ASA prints can significantly improve their aesthetic appearance, creating a glossy, smooth surface finish that looks more like an injection-molded part. This process works because ASA, similar to ABS, is soluble in acetone.
The Process: Acetone Vapor Smoothing
Vapor smoothing with acetone is the primary technique for achieving a smooth finish on ASA prints.
How it Works
When an ASA print is exposed to acetone vapor in a controlled environment, the surface layers of the plastic begin to dissolve and flow slightly. This process melts away the layer lines and minor imperfections, resulting in a uniformly smooth and often glossy surface as the acetone evaporates and the plastic re-solidifies.
Steps for Acetone Vapor Smoothing
Here's a general outline of the process:
- Prepare a Smoothing Chamber: You need an enclosed container that can hold the print and the acetone vapor. Glass or metal containers are often preferred as acetone can affect some plastics.
- Introduce Acetone: Place a small amount of liquid acetone in the bottom of the chamber or on absorbent material (like paper towels) around the perimeter. Ensure the liquid acetone does not directly touch the print.
- Elevate the Print: Suspend the 3D print inside the chamber so it is exposed only to the vapors, not the liquid acetone. You can use a wire rack or stand for this.
- Seal the Chamber: Close the container to allow the acetone vapors to build up and work on the print's surface.
- Monitor the Process: This is crucial. The time required varies depending on the print size, chamber size, acetone amount, and desired finish. Start with short exposures (e.g., 10-20 minutes) and check the print's progress. Overexposure can damage the print, causing drips, loss of detail, or deformation.
- Remove and Dry: Once the desired level of smoothing is achieved, carefully remove the print from the chamber. Place it in a well-ventilated area to allow the absorbed acetone to evaporate completely and the plastic to harden. This drying process can take several hours, sometimes even days for larger or denser parts.
Safety Precautions
Acetone is highly flammable and its vapors are toxic. It is essential to take precautions:
- Perform the process in a well-ventilated area, away from open flames or sparks.
- Wear appropriate personal protective equipment (PPE), such as chemical-resistant gloves and safety goggles.
- Avoid inhaling the vapors.
- Store acetone in a tightly sealed container away from heat sources.
Alternatives and Considerations
While acetone vapor smoothing is the main method, consider these points:
- Mechanical Smoothing: Sanding and polishing can smooth ASA prints, but this is labor-intensive and might not reach intricate details.
- Protective Coatings: Applying a clear coat or epoxy resin can hide layer lines and provide a smooth finish, though this adds material thickness and can obscure fine features.
- Process Control: Achieving consistent results with vapor smoothing requires practice and careful control of exposure time and vapor concentration.
Using controlled exposure to acetone vapors is the established technique for effectively smoothing ASA 3D prints, transforming a layered surface into a smooth, professional-looking finish.
