Acetone smoothing PLA prints – finish with visible layer lines

Many people claim that ABS is simple to smooth (with acetone baths and other techniques), but what about PLA?

  • The majority of non-acetone-dissolving PLA and comparable 3D printer filaments cannot be smoothed in the same manner as ABS. This is because PLA does not react with acetone when it is pure.
  • Due to the addition of other materials, PLA and acetone smoothing can be used. You can occasionally use acetone to smooth out very inexpensive PLAs that have been mixed with less expensive plastics to create a less pure PLA. On the other hand, modified PLAs with additives can at least be acetone-bonded and enable vapor smoothing PLA.

To learn how to dissolve PLA filament and make it much smoother than it is just after it leaves the print bed, keep reading.

How does acetone smoothing pla work?

  • The method of smoothing PLA prints involves getting rid of the layer lines that are apparent on 3D-printed items. PLA 3D prints that have been smoothed are just that—smooth. The print’s exterior loses its 3D-printed appearance and takes on a more injection-molded appearance.
  • There are other ways to make PLA 3D prints appear smooth surface, but they all involve either eliminating the excess plastic that creates the visible layer lines or filling up the minuscule spaces between the visible layers with a brush-on coating. Each approach has advantages and disadvantages, and some work better for particular tasks than others.

Smoothing PLA 3D prints

Sanding 3D prints

Sanding PLA is one of the easier ways to smooth out prints, and as you may have discovered in your experimentation, there are numerous approaches to sanding. You might wish to think about using a sanding block if your print has vast surfaces. They free up your hands from the work and guarantee even sandpaper wear as well as wear on your print.

Sanding is the process used most frequently to smooth 3D prints. This technique is very useful because it is safe, affordable, and offers no health hazards. It is not particularly suited for fine features or reaching deep crevices, and it is also one of the most time-consuming methods to smooth PLA print.

Depending on the use of the parts and the level of smoothness desired, sanding can be done in a variety of methods. A sanding block, which is a piece of wood with sandpaper wrapped around it, may be needed for large sections, but nail files may be more appropriate for little parts and delicate details.

Despite their excellent efficiency, electric sanders should not be used on PLA prints because the heat they produce can melt the material and cause it to deform.

For the majority of prints, the outer surface of the item is first sanded using coarse 200 or 400-grit sandpaper, either loose or wrapped around a sanding block, in circular motions to eliminate any pronounced protrusions. A slightly finer wet sandpaper is used once the entire component has been sanded, working up to 3,000 grit in increments.


For a shiny surface, a polishing stage using a cotton cloth and liquid plastic polish can be used after the sanding stage, which leaves a smooth but matte finish. Similar to sanding, polishing 3D prints requires moving a damp cloth over the part’s surface in even circular motions until the surface is shiny and smooth.


By removing the raised “steps,” layer lines can be less noticeable with only sanding, but another method is to fill in the cracks with primer spray before sanding off the extra primer. Because priming is simpler to sand than PLA itself, this technique works well.

Priming takes the longest to complete since it needs to be applied between each round of sanding and allowed to dry. The results are superior to sanding alone, though. A very thin coat of primer is sprayed evenly over the PLA prints in a well-ventilated location when it is being primed. Before the initial round of sanding, one or two further coatings can be applied.

After that, alternate priming and sanding are done, and 3,000 grit sandpaper is used to finish. Spray painting normally comes after priming and sanding, since uncoated primer is more prone to being damaged by impacts and the environment. Also take note that plastic filler, not primer, should be used to fill particularly deep voids.

Epoxy resin coating

Epoxy resin coating is a distinct kind of coating that may be used to smooth PLA prints. It comes in two parts (resin and hardener), which must be combined before use. The epoxy resin coatings may be applied to parts using a paintbrush and are appropriate for filling even the deepest holes, unlike primer, which comes in a spray can.

Wet sand the PLA parts with fine-grit sandpaper first to guarantee strong adherence to the epoxy. The epoxy can be applied liberally and spread uniformly across the surface of the part once it has dried. Epoxy can be applied in additional layers until the required degree of smoothness is achieved.

Keep in mind that the 3D prints underlying the epoxy resin covering may be weaker, and with time, pieces of the coating may flake or chip off. There are combinations made expressly for smoothing 3D printers, such as Smooth-On XTC-3D, in addition to generic epoxy resins, which can be utilized.


One of PLA’s major drawbacks is that it cannot be chemically smoothed with acetone, a very safe procedure that works well for materials like ABS. Stronger chemicals that call for lab supplies like nitrile gloves, protective eyewear, fume hoods, and a well-ventilated area can only be used for the chemical smoothing of PLA prints.

These chemicals remove the top layer of the material, leaving a flawless finish, but they can also remove other materials like human skin, work surfaces, and plastic containers. Experienced users may use solvents like tetrahydrofuran, dichloromethane, or chloroform to smooth PLA 3D prints. These chemicals can be dangerous to use and are challenging to obtain.

Ethyl acetate, a solvent used in regular nail polish remover, is a safer alternative. Although it has a limited amount of effectiveness, ethyl acetate can be applied to smooth PLA prints using a cloth or cotton swab. PLA print is not very well adapted to chemical smoothing in general.

Vapor filtration

Using an automated vapor smoothing device, like the Polymaker Polysher, which produces a mist of alcohol to gently remove the top layer of PLA parts, is a secure and efficient way to chemically smooth PLA parts. Unfortunately, the Polysher only works with Polymaker’s alcohol-soluble PolySmooth and PolyCast-modified PLA materials.

Smoothing PLA with a heater

Even though it’s not the most accurate PLA smoothing method, melting a part’s exterior using a heat gun is a quick and simple solution to get rid of layer lines. A heat gun is a tool that looks like a hairdryer but has a significantly larger temperature range.

To smooth 3D prints using a heat gun requires even movement of the gun to provide even heating of the part surface (or place the part on a revolving platter and keep the heat gun steady). This smoothing process only can be used on medium-sized or big parts without hollow portions or tiny details.

You may also be interested: How to paint PLA on one’s own

Chemical glamour

The quick answer to the question, “Are there chemicals that smooth PLA like acetone smooths ABS?”, is “yes.” Some substances, like ethyl acetate, can vapor smooth PLA, but they are not recommended for a variety of reasons:

  1. Additionally, we do not advise utilizing them because they are expensive, hard to get, and extremely dangerous (particularly when vaporized). Inhaling ethanol acetate in particular is extremely combustible and poses a serious health risk.
  2. Lye, often known as Sodium hydroxide, is an additional choice. This procedure is also not something we can endorse, especially if you want to use it at home. It’s a harmful material, and typically, it won’t smooth out your print; instead, it will probably cause the object to break up into tiny pieces.


Can you smooth PLA with acetone?

Acetone won’t significantly affect your 3D print because it doesn’t affect PLA plastic in the same way as it does ABS. ABS degrades in acetone because it is acetone soluble. You must purchase PolySmooth or any post-processing-friendly filament if you want the PLA printing experience with the convenience of acetone smoothing.
Finding a chemical PLA smoothing method is not possible because PLA has few chemical reactions (and even fewer that function like acetone and ABS). Acetone is an excellent tool for cleaning your hot end and joining two 3D-printed pieces, among other things. But you should be aware that acetone can also be extremely hazardous if handled improperly.

  • Avoid using acetone near anything that could catch fire or generate a spark because it is highly flammable. Additionally, make sure you are working in a space with enough ventilation because too much inhalation of the vapor might result in headaches, vertigo, and a sore throat.

How do I get a smooth finish on PLA?

Sanding PLA.
Epoxy resin.
Vapor smoothing.
Heat gun smoothing.

Can you use acetone to smooth 3D prints?

Sanding, epoxy resin, priming, and surface melting are non-solvent techniques that are generally safer but take longer. Acetone works well to smooth ABS prints; however, it does not effectively dissolve PLA filament. PLA parts can be speedily smoothed using ethyl acetate vapor.

Is PLA affected by acetone?

Acetone doesn’t totally dissolve PLA; instead, it tends to make it sticky or rubbery. A print’s durability and surface quality may suffer as a result. Acetone smooth is an excellent alternative for smoothing ABS but not the greatest to smooth PLA 3D prints.


There are various ways to make your PLA prints look fantastic, whether you prefer the cleaner appearance of finished prints or need a smooth surface for functioning. The methods are quick and inexpensive, and PLA filament can create useful printed items with a reasonable level of rigidity and strength.

Although smoothing PLA parts layer lines can be more difficult to smooth than some other 3D printing materials, there are several techniques and equipment you can use to make the process as painless as possible. As an alternative, resin 3D printing methods like SLA and DLP are far better at creating smooth items without layer lines than FDM.

Read also: What to do when PETG sticks to nozzle: A step-by-step guide

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