How to Smooth a PLA 3D Print

As an avid 3D printing enthusiast, I know from experience that the quality of a 3D print can make or break a project. Even a seemingly small imperfection can detract from the overall appearance of a print, which is why I’m excited to share my knowledge on how to smooth PLA 3D prints. PLA, or polylactic acid, is one of the most popular types of filament used in 3D printing due to its ease of use, affordability, and biodegradability. However, PLA prints can be prone to rough surfaces and visible layers, which is where smoothing techniques come in handy.

Understanding PLA Filament

Before we dive into smoothing techniques, it’s important to understand PLA filament and how it behaves during printing. PLA is a thermoplastic and melts at a relatively low temperature, which makes it easy to work with. However, this also means that it cools and solidifies quickly, which can result in visible layers and rough surfaces. Additionally, PLA is more brittle than other filaments, which means that it can be prone to cracking or breaking under stress.

Factors Affecting PLA Print Quality

Several factors can affect the quality of PLA prints, including print speed, temperature, and cooling. If a print is too fast or too hot, it can result in stringing or blobbing, while cooling too quickly can cause warping or cracking.

Smoothing Techniques

Now that we understand PLA filament and its characteristics, let’s explore some techniques for smoothing PLA prints.


Sanding is one of the most straightforward and effective ways to smooth PLA prints. This technique involves using a fine-grit sandpaper to sand down the surface of a print, which can remove visible layers and create a smoother finish. Start with a low grit sandpaper, such as 220 or 320, and gradually work your way up to a higher grit, such as 1000 or 2000, for a polished finish. Be sure to sand in a circular motion and avoid applying too much pressure, as this can damage the print.

Acetone Vapor Bath

An acetone vapor bath is another popular technique for smoothing PLA prints. This technique involves placing a print in a container with a small amount of acetone and allowing the fumes to smooth the surface of the print. Be sure to use a well-ventilated area and protective gloves when using acetone, as it can be harmful if ingested or inhaled. Additionally, make sure to monitor the print closely, as exposure to acetone for too long can cause the print to melt or warp.

Epoxy Coating

An epoxy coating is a more advanced technique for smoothing PLA prints, as it involves applying a layer of epoxy resin to the surface of the print. This technique can create a glass-like finish and is ideal for prints that require a high level of detail or precision. However, it can be time-consuming and requires some skill to apply evenly. Additionally, epoxy resin can be toxic if ingested or inhaled, so be sure to use protective gear and work in a well-ventilated area.

Polishing Compound

Polishing compound is another effective way to smooth PLA prints, and it’s relatively easy to use. This technique involves applying a small amount of polishing compound to a soft cloth and rubbing it onto the surface of the print in a circular motion. Polishing compound can remove visible layers and create a glossy finish, but be sure to use a light touch and avoid applying too much pressure.

Heat Gun

A heat gun is a more aggressive technique for smoothing PLA prints and should be used with caution. This technique involves heating the surface of a print with a heat gun, which can melt the surface slightly and create a smoother finish. However, it’s essential to use a low heat setting and keep the heat gun moving to avoid melting or warping the print.

FAQs for how to smooth a PLA 3D print

What is PLA and why is smoothing necessary?

PLA, or polylactic acid, is a very popular 3D printing material due to its ease of use, biodegradability, and low toxicity. However, when 3D printed, the surface of a PLA object can often have a rough, layered look due to the way the material is deposited layer by layer. Smoothing PLA can improve the appearance of the print, making it look smoother and more professional.

How can I smooth my PLA 3D prints?

There are several methods you can use to smooth PLA 3D prints. One method is sanding. You can use fine-grit sandpaper to smooth the surface of your PLA print. Another method is vapor smoothing. This involves exposing the PLA object to fumes from a solvent, such as acetone. You can also use a heat gun or a flame to smooth PLA. This involves heating the surface of the PLA object with a heat source until it melts, and then quickly cooling it to create a smooth surface.

What are the benefits of smoothing PLA?

Smoothing PLA can provide several benefits, including improving the aesthetic quality of the print, making it look more professional and polished. Additionally, smoothing can help remove imperfections and rough spots that can make it difficult to use or handle the print. In some cases, smoothing can also make a print more durable and stronger.

Are there any risks associated with smoothing PLA?

Yes, there are some risks associated with smoothing PLA. One of the biggest risks is exposure to fumes when using vapor smoothing. The fumes can be harmful to your health, so it is important to use proper ventilation and safety measures when using this method. Heating PLA with a heat gun or flame can also be dangerous if not done carefully, as it can cause the PLA to catch fire or become deformed.

Are there any alternatives to smoothing PLA?

Yes, there are alternatives to smoothing PLA. You can try changing the settings of your 3D printer to create a smoother surface. This includes adjusting the layer height, print speed, and temperature settings. Additionally, you can try using a different material, such as ABS or PETG, that may naturally produce a smoother surface when 3D printed.