Dissolving PLA Filament: Here’s What Works

PLA or polylactic acid filament is a popular, organic alternative to the plastic filament. As a result, it’s one of the most popular filament types used by home 3D printers.

But, if you want to clean up the melted filament, smooth ridges, or otherwise dissolve PLA for one reason or another, that can prove a challenge. 

In fact, there’s no one way to dissolve any PLA. Instead, different chemicals and methods are needed for different types of PLA. However, ethyl acetate is the go-to in the industry and is normally the first thing you should try to dissolve PLA. 

Which Solvents Can Dissolve PLA Filament?

If you’re looking for a solvent to dissolve PLA filament, there are plenty of options that will do the trick.

However, most vary in application and efficacy, meaning you should pick a solvent for the purpose you want. E.g., if you want to dissolve and smooth the surface, acetone probably isn’t the best call. 

Importantly, there are many more chemicals that dissolve PLA filament. However, the following include some of the most common and easy to acquire. 

Chemical	Efficacy	Method	Safety
Pyridine	High	Wipe On	Low
Ethyl Acetate	High	Vapor/ Wipe On	Mid
Methyl Ethyl Ketone	High	Brush On	Low
Sodium Hydroxide	Mid	Brush-On/Vapor	Mid
Dichloromethane	High	Dip/Vapor	Low
Tetrahydrofuran	Mid	Brush On / Soak	Low

Pyridine  

Pyridine can be used to melt layers of PLA together to create a smooth surface on your print. This chemical is highly effective and should be diluted before use.

In addition, all you’ll have to do is mix the pyridine with water and wipe it onto the print, then wait for the print to dry. 

However, pyridine is also highly toxic and easily flammable. It’s not recommended to work with it in a home environment. Instead, you should work with it in a ventilated workshop, away from flammable materials.

Wear gloves, a mask, and protective eyewear. You should also always wash your hands after handling pyridine. 

Ethyl Acetate 

Ethyl Acetate is the go-to solvent for PLA. That’s normally because most people already have it in their homes in some form.

In fact, many types of nail polish remover are made with ethyl acetate. Ethyl acetate is also one of the safer chemicals on this list. However, the methods normally used to smooth PLA with ethyl acetate still require a mask and eye protection. 

Here, most people use the vapor method, where you heat ethyl acetate until it steams and hold the part in the vapor. In other cases, a brush on approach may work as well.

It’s extremely important not to vaporize ethyl acetate without a mask and a well-ventilated area. 

Methyl Ethyl Ketone 

Methyl ethyl ketone or butanone is commonly used for sterilizing electronics, surgical tools, and as a base ingredient in paint.

However, it’s also a harsh solvent, which can quickly dissolve and smooth PLA. As an industrial-grade solvent, though, you may not be able to get it in your area. 

If you do get it, methyl ethyl ketone can be brushed on to rapidly smooth the surface of the PLA. 

MEK is also highly flammable and explosive. It’s important to only use it in a well-ventilated area, away from any sources of heat. 

Sodium Hydroxide

Sodium hydroxide is a commonly available caustic soda. This material is the second choice next to ethyl acetate, because many stores sell it, so you can easily acquire it.

However, sodium hydroxide is highly caustic and should not be handled without protective clothing, gloves, and a mask. 

Here, you treat the print by dissolving caustic soda in water. Most use about a cup of soda per quarter gallon of water.

Then, briefly submerge the print in the water. You can always put it back in if it’s not smooth enough. Once smooth enough, you should rinse the soda off. 

Sodium hydroxide can cause severe chemical burns and should be handled with care. 

Dichloromethane 

Dichloromethane is an extremely toxic chemical that can cause significant negative effects on the nervous system, the liver, and the lungs. It is critical that if you use this chemical, you do so with a full PPE including a respirator, gloves, and body covering. 

However, even a small amount of PPE brushed onto PLA filament can dissolve it. That makes this chemical extremely good at smoothing your PLA prints.

However, like most of the items on this list, it’s not recommended for home use. Instead, you shouldn’t be using it without a ventilated workshop and good safety materials. 

Tetrahydrofuran

Tetrahydrofuran is an ideal agent for vapor smoothing PLA prints. However, the vapor is also extremely toxic.

Use full eye protection, a respirator, and gloves when working with it. It’s also important to keep tetrahydrofuran away from open sources of heat, as it is extremely flammable. 

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How To Dissolve PLA In 11 Steps

There are two primary reasons you’d want to dissolve PLA; cleaning and smoothing. 

Cleaning PLA With Chemical Solvents 

If you want to use a chemical cleaner to soften PLA to clean it off of a glass plate or a nozzle, you can use the following steps to clean up PLA. 

1. Mix 1 cup of caustic soda with a quarter gallon of water. Make sure you use gloves, a mask, and appropriate ventilation.
2. Submerge the part in the solution. Make sure that the part is made of glass or metal as plastic and other materials may dissolve
3. Wait one minute then remove the part from the bath.
4. Rinse the part in a bucket of lukewarm water. Inspect it to see if it is cleaner or if the PLA can be scraped off now that it is softer. 
5. If not, repeat the bath. 

Always follow safety instructions and make sure you dispose of caustic soda in accordance with local environmental requirements. 

Smoothing PLA With Ethyl Acetate

1. Pre-sand your 3D print.
2. Clean the 3D print.
3. Use a paintbrush to quickly brush a single coat of ethyl acetate onto the print.
4. Allow the ethyl acetate to dry and then wait 20 minutes.
5. Use a plastic brush to brush the print down.
6. Check to see if the print is smooth enough. If not, repeat the process.

Ethyl acetate is mostly safe to work with. However, you should use gloves, a mask, and ensure you have appropriate ventilation. 

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What Not To Use For Melting PLA

In most cases, it’s a good idea to avoid using chemical solvents for PLA at all. That’s because most are not suitable for use in the home.

However, if you’re accustomed to using ABS plastic, it’s important that you avoid using those solvents on your PLA. 

Acetone

Acetone is the go-to solvent for ABS filament. However, if you soak your PLA in it or use a vapor method to smooth it, you’re more likely to end up with rubbery or sticky PLA. Dissolving PLA in acetone is impossible.

Unfortunately, that rubbery or sticky finish may never go away – unless you use another chemical bath to dissolve that layer. For this reason, acetone is a poor choice for dissolving PLA. 

Isopropyl Alcohol 

Isopropyl alcohol is another go-to for ABS plastic. Like Acetone, it also doesn’t work on PLA. However, there is one exception.

If you have Polymaker, it’s specifically designed to dissolve in isopropyl. For this reason, if you want to use the same smoothing methods you do on ABS, choosing a brand like Polymaker is a good idea.

Otherwise, isopropyl does not work. 

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4 Non-Solvent Processes To Smooth PLA

Non-solvent PLA smoothing is normally considered the way to go for most home setups. That’s because it’s safer, usually more effective, and can be achieved with products you have at home.

Here, there are four primary options to smooth PLA without solvents: 

XTC-3D

XTC-3D is a 2-party epoxy resin designed to brush onto 3D print models. The resin fills the gaps and layers, leaving you with a smooth surface.

XTC-3D works like any other resin, meaning you mix the resin with the hardener and then brush it on quickly. Once it’s there, it’s permanently fixed. 

However, XTC-3D is not suitable for models with very fine detail. That’s because the resin may clog or fill the details and you may lose them.

Instead, this is a better fit for larger surface areas, where you mostly want a completely smooth finish without worrying about tiny detail work. 

Glue 

Many people use glue to coat the surface of their PLA to smooth out any imperfections in the surface.

Here, brands like 3D Gloop offer formulations specially made for PLA. However, any glue stick or brush on glue will also work – providing it sticks to PLA.

Like with resin, you’ll want to ensure that you’re not applying it to anything with fine details because you may lose them. 

Sanding 

Sanding and buffing is the primary method of removing prints lines from PLA. Here, you’re usually best off choosing to wet sand, grading down to a very fine paper to achieve a good polish.

Sanding fine details like minis can be extremely difficult. In this case, you normally want to use a brush. Finally, you can buff off any sanding marks with a buffing cloth. 

Heat 

Heat guns are commonly used to warm PLA to allow you to smooth it to remove lines. However, this method is normally used to remove burrs and protrusions.

You may also use it before sanding or buffing to make it easier to smooth rather than sand off any visible lines. 

Heat is also a better choice than dissolving PLA support material, because it’s less likely to damage the rest of your print. In this case, you can heat the supports and then cut them, rather than waiting for a chemical solvent to do the work. 

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Final Thoughts

There are plenty of chemicals that dissolve PLA filament. Unfortunately, most of them are not safe for use in the home. If you do use one, make sure you use work in well-ventilated conditions, with PPE (mask/respirator, gloves, body covering), that you work away from open heat sources, and that you take precautions to protect yourself, anyone else in the building, and the space. 

Non-chemical PLA smoothing is usually the way to go, even if sanding can take time.