PLA Filament for your 3D printer

Introduction

PLA is the most widely used polymer in 3D printing. It is favoured for its ease of printing, versatility and its relatively low cost. Here you can find all the suppliers of PLA filaments listed in the directory and optimal print settings based on supplier data and user feedback. You can also find everything you need to know about printing with PLA, from its discovery to its physical properties to how it can be post-processed.

Best temperature settings for speed, weighted by the satisfaction

Best adhesion solution, weighted by the user satisfaction

About

PLA Discovery

PLA was first discovered in 1932 ² by Wallace Carothers, who is also credited with the discovery of Neoprene and Nylon, whilst working for the chemical company E. I. DuPont de Nemours and Company (DuPont). The production process was originally patented by DuPont in 1954. Production of PLA was extremely expensive so it was used mostly for medical grade applications. It wasn't until 1989 that Dr Patrick R. Gruber and his wife Sally developed a way of making PLA from corn-starch using their kitchen stove. Cargill-Dow Polymers, now known as NatureWorks LLC, was the first to produce PLA at a commercial scale in 1997.

How is PLA made?

PLA is made in a two-step process. Naturally occurring lactic acid or lactide is first obtained from sources like corn starch using a fermentation process. Lactic acid is then converted to high density PLA using an industrial chemical process called Ring-Opening Polymerization which is catalysed by metals like tin. You can read more about the PLA production process ¹¹. NatureWorks LLC is currently the biggest PLA producer in the world and have recently expanded their product line to include 3D printing specific PLA ¹⁴.

Physical properties of PLA

Property	Value
Chemical Formula	(C3H4O2)n
Chemical Structure
CAS Number	26100-51-6 4
SPI Resin Identification Code 16	7
Crystallinity	37%
Glass Transition	60-65°C
Melting Temperature	150-160°C
Printing Temperature	178-240°C
Density	1.210-1.430g/g/cm3
Tensile Strength*	49-56MPa
Tensile Elongation*	0.5-9.2%
Flexural Strength*	48-110MPa
Water Soluble?	No
Other Solvents	Chlorinated Solvents, hot benzene and dichloromethane are commonly used PLA solvents. A more complete list can be found here 19
Example Technical Date Sheet	Ingeo 3D850 Biopolymer TDS 13
Example Safety Data Sheet	Ingeo 3D850 Biopolymer SDS 12

*ASTM D638 Test Method ¹.

Further technical data for PLA can be found here ¹⁷.

Advantages of PLA

Printing

PLA tends to be low cost and is available in a wide variety of colours. It is considered to be very easy to print with due to its low glass transition temperature and melting temperature.

Biodegradability:

PLA has the huge advantage of being bio-based meaning that it can be degraded by naturally occurring microorganisms in the right conditions, unlike synthetic plastics. There is an important distinction to be made here that just because PLA is biodegradable this does not necessarily mean it is compostable. To find out more about the difference between a biodegradable and a compostable material, read our blog post here. A study by the California State Department of Resources Recycling and Recovery ³ found that in a marine environment PLA degraded by only 8% after 12 months, similar to the 6% of a standard Low Density Polyethylene plastic bag. Another study from the National Metal and Materials Technology Centre ²⁰ found that after 15 months in landfill conditions PLA samples became brittle, deformed and opaque but showed little to no signs of decomposing. It is not all doom and gloom for PLA though, the same study found that under properly controlled composting conditions PLA samples degraded by 86% in just 4 months. To achieve this the compost pile needs to be kept at 45-70°C, 40-55% humidity and pH4-8. In a commercial composting facility PLA can be composted in just 90 days, in a garden compost heap it will take closer to 6 months depending on the size of the product as well as temperature and humidity. This is a significant improvement over PLA's synthetic counterparts.

Biocompatibility

PLA Is biocompatible meaning that it can be in contact with living tissue without being toxic or causing an immune response. PLA is also a bioresorbable material, meaning that it can be broken down by the human body into non-toxic lactic acid. It is for these properties that makes PLA ideal for medical grade products such as medical implants that need to degrade over time.

Food Handling

In its solid form, PLA is non-toxic so it can be used for food handling below its glass transition temperature however it is extremely important to ensure that the entire 3D printed product is food grade, not just the resin. For example, manufacturers may mix colourings and other additives that are not food safe with the resin. Always check the Material Data Safety Sheet (MSDS) to make sure the filament is food safe! You must also remember that most PLA is not dishwasher compatible because of its low glass transition temperature. This is important because bacteria can easily build up in the small ridges characteristic for 3D printed products. Using a food safe sealant or epoxy can help to prevent this build-up. Alternatively, you can wash your product with lukewarm water and antibacterial soap immediately after use to help prevent bacterial build-up. Lastly, you should use a food safe hot end/extruder (usually made from stainless steel). This is because other extruder materials can contain contaminants that may enter your product, for example brass nozzles may contain lead.

Disadvantages of PLA

Printing

PLA has a lower glass-transition temperature (around 57°C) than many of its alternatives. This does make PLA very easy to print with however it also makes it unsuitable for products that will be exposed to high temperatures as it may soften and deform. PLA also has a lower impact strength and elongation resistance than ABS however new PLA filaments specifically designed for 3D printing have a higher heat grade and impact grade, comparable to ABS.

Flammability

PLA has an NFPA 704 ⁷ flammability rating of 1, meaning that it requires significant preheating before it will burn under all ambient temperature conditions. PLA can accumulate static charge which may cause an electrical spark that can act as an ignition source. Water, alcohol resistant foams and carbon dioxide are all suitable extinguishers for burning PLA. There are no currently known unsuitable extinguishers however general purpose synthetic foams or protein foams may be less effective. Always check the MSDS.

Recycling

At the moment PLA is not easily recyclable. One of the key issues with recycling PLA is that PLA is not usually disposable in mainstream plastic recycling streams. This is because it cannot be distinguished from PET during floatation and density tests. It is estimated ⁸ that as little as 1 PLA bottle per 1000 PET bottles is enough to contaminate the recycled PET batch.

Printing with PLA

Considerations

Before you begin your print make sure you have checked that PLA is the correct filament for your project. You need to consider what the final product will be used for and what temperatures it will be exposed too... remember PLA has a low glass transition temperature!

PLA Filament Storage

PLA is hygroscopic, meaning that it will absorb water from the air. This results in increased brittleness, filament breaking, bubbling when printing or filament degradation. In some cases, this can lead to filament jamming in your printer's hot end, it may even require replacing the hot end if the jam is severe. This can be avoided by storing your filaments in vacuum bags with silicagel "dry packs". You should also avoid storing filament for a long period of time. To read more about protecting your 3D printing filaments from humidity you can read our blog post.

Print Environment and Safety

Unlike ABS or other 3D printing filaments, PLA does not release foul smells at its melting temperature however you should still print in a well ventilated area as 3D printing any plastic type may be a source of ultrafine particles ²¹ which should not be inhaled.

The Base Layer

Using a good base layer material is imperative to ensure that the first print layer adheres properly and does not unstick during printing. To find out more about the importance of adhesion and the base layer you can read our blog post.

• Painters tape is a very popular base layer choice as it is easy and fast! When using painters tape, you must make sure that the tape covers the entire plate without any gaps or overlaps. Using a heated bed with blue tape may reduce the ability of PLA to adhere to the tape. Tape will need replacing every 5-10 prints as it loses its ability to adhere to the PLA. This has been a common method for some time however with newer printers there are some better alternatives.
• Polyetherimide (PEI) is a slight upgrade on painters tape. It is suitable for both PLA (hot or cold bed) or ABS (hot bed) printing. A PEI sheet can be stuck directly to your glass bed using adhesive transfer tape and requires no other processing.
• Printing directly onto glass with a heated bed is another option. This method gives a nice flat base layer with a shiny finish however it is a little trickier than using blue tape. The bed should be heated to around 70°C for 3D printing with PLA.* Another common method for ensuring good adhesion is smearing Pritt glue onto the glass ¹⁵. This method is cheap and easy to clean with good results.
• Spray on 3D printing bed adhesives like DimaFix Fixative Spray ⁵ have excellent results. Adhesive sprays can be water-based which are much easier to clean than their alternatives. If the spray is not water-based it will probably require cleaning with denatured alcohol.

The First Layer

The first print layer is essential to get right in order to prevent unsticking during printing. There are three key factors to consider here:

• The Print Bed: The bed must be perfectly level. The bed is usually kept between 45°C to 60°C for PLA printing. This helps with first layer adhesions however it is not strictly necessary as PLA has very low warp.
• The extruder must be at the correct height from the bed to allow the PLA filament to squish and adhere to the base material properly. Too high and the PLA will not adhere to the base layer. Too low and the bed will completely block the extruder.
• Use a good base layer that will adhere well to your PLA filament.

Print Temperature

PLA filament printing temperature can range anywhere between 178°C - 240°C however for most PLA 3D printing filaments the range is closer to 190°C - 220°C. Higher quality PLA filaments often print at a lower temperature due to purity of resin and lack of contaminants however the printing temperature can also be affected by the filament colour and other superpowers such as glow-in-the-dark. Always check the Technical Data Sheet for the recommended print temperature. You can also consult our Go-To print settings tool which has been created by analysing all the successful print settings that the Filaments.directory community have uploaded. The optimal printing temperature will also be affected by your printing environment so it is a good idea to do some test prints and vary the temperature by 5°C increments until it runs smoothly. Due to its low glass transition temperature and low melting temperature, PLA adheres very well.

• If the printing temperature is too hot then you will find that the extruder may leak PLA whilst moving around, you may also find that there are more thin trails of plastic between different areas of your print. When this happens just lower the printing temperature until the extruder is no longer leaking PLA.
• If the printing temperature is too cold then the layers of PLA will not adhere to each other properly. This may result in a rough surface or weak areas that can be easily pulled apart.

Print Speed

3D printing PLA should work at speeds between 30mm/second to 90mm/second however this will vary depending on the filament and your printer. Some PLA 3D printing filaments have been specifically designed for printing at higher speeds REFERENCE. For higher quality prints, speeds at the lower end of this spectrum are appropriate. Just like temperature you will find that it is best to start with a speed and incrementally increase or decrease it to find the optimum. In general, a higher print speed will require a higher print temperature too. This is because faster printing requires lower viscosity in your 3D printing filament which can be achieved at higher temperatures.

Cooling

Cooling your PLA with a dedicated fan is one of the most important aspects of producing good quality PLA 3D prints. Having a cooling fan running at or near 100% power will ensure that the PLA drops below its low glass transition temperature as soon as possible. This is an excellent way to prevent any sagging or bending of parts and is made possible by the fact that PLA does not warp significantly when being rapidly cooled. This can also help to prevent stringing of PLA between seperate parts. For most PLA 3D prints, running a fan at 100% is appropriate after the first layers have been printed and successfully adhered to the base layer.

Closed Chamber Printing

Closed chamber printing is not strictly necessary for 3D printing with PLA as PLA is low warp and does not give off toxic fumes however it may help when printing in humid environments to prevent your PLA filament from absorbing moisture from the air.

Problems

Problems with PLA 3D printing mostly arise during first layer adhesion, these can often be addressed by ensuring the print bed is perfectly level and that the extruder is at the correct height. As previously mentioned, some experimentation will be required to ensure you have the optimum speed and temperature settings for you printer and project. When in doubt, consult the Technical Data Sheet for the recommended settings and make small, incremental adjustments from there until everything is working properly. You can also consult our Go-To print settings tool which has been created by analysing all the successful print settings that the Filaments.directory community have uploaded. Hissing steam or bubbling from your extruder whilst printing with PLA may be due to improper storage of PLA resulting in your filament absorbing water from the atmosphere.

Post Processing

Removing Supports

If you have a dual nozzle printer you can print your supporting structures in a low density, water or chemical soluble 3D printing filament which can simply be soaked in the relevant solvent to remove. PVA is a water-soluble 3D printing material that is commonly used as a support structure for dual nozzle PLA 3D printing. If you have printed using only PLA your structural supports should be thin enough to simply remove with some needle nose pliers. Alternatively, you can wet-sand the product with some high-grit sandpaper.

Removing Excess

You may find that your print has little burrs or lips that need to be removed as they can often feel quite sharp and prevent pieces from fitting well together. As PLA is relatively brittle so cutting these off is not always the best option, instead a light file will easily smooth them out. Make sure your PLA print does not get too hot whilst you are filing it! A Dremel ⁶ is commonly used to grind down 3D printing products however this should be avoided for PLA 3D prints as the friction will rapidly cause the product to get too hot.

Polishing

You can polish your PLA product by wet-sanding up to 2000 grit, cleaning and allowing to fully dry then buffing with a plastic polish such as Blue Rouge. Another safe method for polishing your 3D print is to use products like the Polymaker Polysmooth ¹⁸. PLA Prints can also be polished using Tetrahydrofuran (THF) however this should be used as a last resort as it is far more hazardous than the alternatives! *Warning THF is an extremely strong solvent and can penetrate skin causing rapid dehydration, it is also somewhat toxic and should not be ingested or used for products that will be in contact with food or handled by children. Use THF in a very well-ventilated area and use non-latex gloves like nitrile or neoprene as THF will rapidly dissolve Latex. An alternative method for polishing your products is a rock tumbler like the one designed by Joerg Torhoff ¹⁰.

Epoxy

Epoxy can be used to fill gaps in the print and give the product a clear, smooth outer shell. It is worth noting that the 3D printing layer lines will still be visible under the epoxy coat. Epoxy can also be used to glue together PLA print components, alternatively an appropriate PLA plastic glue can be used. *Warning Epoxy resin is generally classed as an irritant. Epoxy hardeners can be corrosive and toxic. Epoxy is toxic to aquatic organisms. Wear gloves when using epoxy and do not let it come into contact with your skin. Repeated skin contact can result in an allergic response to epoxy.

Painting

Your PLA 3D print can be primed with any aerosol primer (use in a well-ventilated area and wear a mask if appropriate). 2 light priming layers are recommended from approximately 20cm away to prevent pooling of paint. After priming you can paint and seal your print. An interesting alternative to painting your 3D printed PLA product is copper electroforming ²⁴, the process of coating your print in metal using an electrolytic bath. You can watch a guide on how to copper electroform your 3D print here ²². Once electroformed you could even use your copper covered print as a base for electroplating with gold or silver! If you are interested in what you can do with electroforming and 3D printing, have a look at the Home Electroforming twitter hashtag ²⁵

The future of PLA

There is ongoing research into making PLA even more eco-friendly (and cheaper). NatureWorks, the largest PLA producer, is working to eliminate the use of non-renewable energy in the PLA production process ²³. Other areas of research include metabolic engineering ⁹ of the bacteria E. coli to efficiently produce PLA in a single step, bio-based process.

High-grade PLA filaments specifically designed for 3D printing are starting to appear in the market ¹⁴. These PLA filaments have higher levels of crystallinity, are more resistant to heat above the typical glass transition temperature and are much tougher and more impact resistant. These high-grade PLA filaments represent a viable alternative to ABS for those that want the strength of ABS with the bio-based nature of PLA or without the need for ventilation when printing.

References

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