Can You Dissolve Polylactic Acid (PLA)? Is it Possible?

Can you Dissolve PLA?

Dissolving PLA is possible. Various types of chemicals react and dissolve parts or all of PLA, such as the following:

• Methyl Ethyl Ketone (MEK)
• Acetone
• Ethyl Acetate
• Tetrahydrofuran
• Caustic soda (Sodium Hydroxide)

Generally speaking, all of these chemicals react with PLA. Most will dissolve the majority of the polymer, depending on the concentration. So, what is the result you are seeking? Your answer to this question will determine which agent you may decide on.

Cleaning Extruder Heads

If you want to find a solvent that can clean extruder heads with gunk of PLA from your filaments, you may want to choose either MEK or acetone.

Depending on the crystallinity or semi-crystalline state of your filament and its formation on the extruder, you will be able to clean the surface with MEK or acetone. Alternatively, filaments can be soaked in ethyl acetate, and it will help clean 3D printer’s extruder heads.

When cleaning, make sure everything is turned off, and your extruder head has cooled. If you apply the solvent with a swab or cloth, be careful to protect your fingers or skin from direct contact.

Using PLA as Supports

If you want to dissolve the PLA that has been used as a support material for your build, you may opt for different dissolving agents. Much like the cleaning method, you may prefer to use Ethyl Acetate can be used to dissolve supports, but there are a few more options that you may want to consider.

Agents for dissolving PLA supports:

• Ethyl Acetate
• Acetone
• Tetrahydrofuran (Oxolane)
• Caustic Soda (Sodium Hydroxide)

Acetone is also an agent that can be used to dissolve supports, but they tend to make the PLA surface softer and stickier, leaving a residue on the final part. Instead of using acetone to have a clean surface after a print, it could be used as a tool for welding PLA surfaces.

Tetrahydrofuran (oxolane) is used in 3d printing as well for dissolving PLA completely. Tetrahydrofuran is rather a dangerous agent and is mostly advised to avoid.

Using caustic soda might be a more readily available and affordable option. Caustic soda, which will act as a base, sodium hydroxide, can be found online. These are commonly used for drains to wash off the gunk in the sewage system.

The Process

The optimum mixture to clean PLA from an ABS build is claimed to be at 3 Molar strength. To make a 3 Molar strength, you will add 120 grams of the caustic soda to a liter of water.

Ingredient:

120 grams of sodium hydroxide, caustic soda  

1 liter of water

How:

1. Use gloves, goggles, and appropriate PPE mentioned for handling sodium hydroxide, caustic soda.
2. Slowly add sodium hydroxide to water to make a three molar strength solution (120 grams/liter).
3. Slowly bring the temperature of the solution to 60 degrees Celsius.
4. Use an ultrasonic cleaner or a mildly agitated solution to mix the solution.
5. Slowly dip the build with the PLA support in the solution bath
6. Wait 2-3 hours and check the part to check on the removal
7. Rinse thoroughly when complete and let dry.

Watch this reference video for a demonstration of the procedure.

Source: Vinland

Always wear proper PPE with all handling of chemicals! If you want to look into purchasing an ultrasonic tank, they are more readily available as instruments for cleaning small items such as jewelry. Additionally, more options are available such as this one that can clean and handle the chemicals.

Other Dissolving Agents Are Not Recommended

You may find other agents will most definitely dissolve PLA. Chemicals such as DCM or even methylamine. Although these are not the worst option, these are highly dangerous chemicals and are best avoided for projects at home.

If this is for industrial use and you have access to fume-hoods, and proper (fully required) PPE, and waste treatment systems, methylamine and dichloromethane are solvents you may attempt for PLA supports and cleaning.  

Again, these are not recommended as both chemicals expel toxic fumes that will dissolve and damage most finished surfaces such as epoxies and plastics.  

Do not use this for dissolving support materials. It is expensive to get rid of properly and is rather a dangerous option. Careful handling is critical, and a test sample should be attempted before using it.

PLA as a Support Material for PETG

Alternatively, instead of dissolving PLA, you could use PLA as a support material for PETG. Since the two materials do not bond strongly, the PLA is easier to slip away afterward. This can work on both a single extruder or a multi extruder.

Using the Same Material as the Build Material

One of the only options for a support material is to use the same filament as the build material with single extruders. Fortunately, this is a budget-friendly option as most common build filaments are generally more cost-friendly than support materials and the chemicals involved with it.

Some pros and cons work as a double-edged sword for using the same material.

If the support material is the same as the build material, there will be a better adherence between the support and the build.

This could be beneficial as it will provide sufficient support during the print, but on the other hand, this will produce poor quality results as it will be more challenging to remove the support.

Even after a hard-manual removal, the surface quality may be rather rough and not perfect. Common methods to remove these types of the support material are using an x-acto knife or a sandpiper.

Other Soluble Supports

The most commonly used support material for dissolving is PVA supports. To run through the important points, review this brief list of the pros and cons:

Pros:

• Soluble will be one of the cleanest methods (if the correct solvent is used to react with all the support material).
• Can be used to support complex and/or internal structures

Cons:

• They easily degrade in moisture and therefore need to be stored properly in a humidity and temperature-controlled setting. As it is good practice to properly store your filaments, proper filament storage is critical for storing PVA.
• In general, soluble supports take a long time depending on the support material and the dissolving chemical and mechanism.
• Chemicals required for dissolving plastic can be harmful and dangerous to handle.

Source: ALL3DP

Safety First

As always, when handling chemicals, safety is first! Where do you start? Start with an SDS. SDS, formerly known as MSDS, is short for (Materials) Safety Data Sheet. All chemicals that you purchase should come with an SDS, but if not, you can generally find general SDS for common chemicals.

Here are some examples of SDS for the chemicals listed in this article.

• Ethyl Acetate
• Acetone
• Tetrahydrofuran (Oxolane)
• Caustic Soda (Sodium Hydroxide)
• Methyl Ethyl Ketone (MEK)

Within an SDS, you will find what kind of dangers are associated with the chemical and appropriate personal protective equipment necessary to stay safe when handling the chemical.

Some primary PPE you may want to look into include:

1. Goggles/Safety Glasses
2. Gloves
3. apron

Final Thoughts

Overall, PLA is one of the polymers that can be dissolved. Why you want it dissolved and how you are using the PLA for your build should determine which chemical you will want to use to dissolve the material. Whichever method you choose, always wear your PPE and be cautious when handling chemicals!