PLA is a wonderful, easy to use, 3D printing material. It is a renewable and biodegradable resource.  It is non-toxic and has a pleasant smell when printing.  PLA filament comes in a wide range of colors and because of its thermal characteristics, is particularly easy to get great prints with.

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What is PLA Plastic?

PLA or Polylactic acid is a thermoplastic polyester. It is commonly derived from renewable resources, such as corn starch, tapioca roots or sugarcane. One of the most attractive things about PLA plastic is that it is industrially compostable, which means it can be broken down back into its base elements through industrial means, and not through a ten thousand year lifespan. It is important to point out that although PLA is compostable it is very robust when used in any normal application such as a 3D printed jig or a manufacturing prototype. In that respect, you can think of it as being similar to iron.  If you were to expose it to continuous moisture or leave it outside, it would "rust" and become brittle and unusable in short order.  But if you had it in your home you would expect it to last nearly indefinitely.

PLA plastic is used in many industries from food packaging to biodegradable medical implants such as sutures, tissue screws, and tacks.  PLA comes in a number of grades; scientific, medical, food safe, and then to the type of PLA used in consumer 3D printing.  PLA's natural melting temperature is around 80°C but it is mixed with other plastics to make it suitable for 3D printing.

If you have printed with ABS filament, you will find PLA filament to be harder, wear more slowly, and be easier to get a nice flat part with. PLA is less thermally contractive and much easier to print big parts with. The thing to consider is that being stiffer and harder also means that it is more brittle.  If the part you're printing will be used where it might receive a lot of banging or sharp collisions, PLA may not be the best material.

The other important consideration when printing parts with PLA filament is knowing what sorts of temperatures the part will be subjected to.  PLA plastic becomes soft at 70°C - 80°C and will deform if used in environments that remain above those temperatures for any prolonged time. This is why you should use ABS or PETG filament at a minimum when you have a design that will be exposed to heat, even as little as the heat inside a car on a summer day. At MatterHackers we generally use PLA filament for all our educational models, test-pieces, and quick-turnaround prototypes, as they aren't going to face any stressful scenarios, they just need to look good.

Most of this engine was printed in PLA (Design by Eric Harrell)
Most of this engine was printed in PLA (Design by Eric Harrell)

Getting the First Layer Right

The first layer is the most important part of any print.  There are a few things you need to do to get the first layer to stick well.

  1. You need the print bed (or print surface) to be level.
  2. You need the nozzle to be the correct distance from the bed at the start of the 3D print.
  3. You need a good base material for your PLA to adhere to.

Below is a video from MatterHackers' 3D Printing Essentials series that will help guide you in the right direction for getting a stellar first layer.

Printing on Blue Tape

Blue Tape, or Painters Tape, is one of the easiest and fastest ways to get a great print from PLA.  Here is a quick checklist of things you want to make sure you are doing.

  1. Check that the Blue Tape creates an even layer. Don't miss any spots.  Don't overlap the edges.
  2. While you don't need to heat the bed when using Blue Tape, if you have the ability to it's recommended to use it. 60°C is ideal.
  3. Replace any tape strips that get damage when removing parts.
  4. Replace the tape after 5-10 prints or when parts stop sticking.
  5. If your first layer is not sticking - make sure the print head is close enough to make a nice squished line of PLA. If that doesn't take care of your problem, you may want to increase the 'first layer temperature' 5 to 10 degrees (start with 5 and increase if necessary).

3D Printing PLA filament material On Blue Tape

Printing On Blue Tape

Printing On Glass With A Heated Bed

When you have a temperature controlled bed, printing directly on glass can be a great option.  The recommended bed temperature for PLA is 65°C.

  1. As with any bed material, having your bed level and extruder at the right height is extremely important when printing on glass.  If your extruder is too far from the glass your PLA will not stick, if it is too low the glass will block the extrusion of material and it will not stick either. You need to get the distance just right.
  2. If your first layer is not sticking
    1. Make sure the bed is level.
    2. Make sure the nozzle is close enough to make a nice squished first layer.
    3. Make sure the speed for your print moves aren't too fast. Printing too fast can cause the plastic to cool too quickly and lift from the bed and cause a failed print. 
    4. Clean the glass with isopropyl alcohol
    5. Use an adhesive like glue stick, Magigoo, or MatterHackers Stick Stick

When you can get it working well, glass is a fantastic way to print PLA. It's the only way to have a shiny bottom layer and one of the easiest ways to have a perfectly flat surface.

3D Printing PLA filament Directly On Glass

Printing Directly On Glass

Other Printing Surfaces

Printing on Kapton Tape

Kapton tape is a tried and true method that is in fact the default bed surface material for every Craftbot 3D printer. To print PLA on Kapton Tape you need to have a heated bed, with the procedure being nearly identical to printing on glass, it just involves more setup and clean up.  For instructions on applying Kapton tape read this article: Bed Surfaces - How to apply Kapton Tape.

Printing on Other Surfaces

There are always new and exciting methods for bed adhesion being developed, so it's important to have a good grasp on what each method is best used for. You can check out our 3D Printing Essentials article about bed surfaces to fully understand the pros and cons of every bed surface you might come across while 3D printing.

PLA can easily be post-processed with sanding or epoxy and then painted.
PLA can easily be post-processed with sanding or epoxy and then painted.

Getting The Temperature Right

When working with a new roll of filament for the first time, we generally like to start out printing at about 205°C and then adjust the temperature up or down by 5 degree increments until we get the quality of the print and the strength of the part to be in good balance with each other.

What to Look for:

If the temperature is too high

You will see more strings between the separate parts of your print and you may notice that the extruder leaks out a little bit of plastic while moving between separate areas of the print.  If this happens you should try to incrementally lower the temperature by 5 degrees until the stringing is brought under control without compromising strength. If you just can't seem to get the stringing to stop, you might want to consider adjusting your retraction settings to increase retraction in increments of 0.5mm or so.

If the temperature is too cold

You will either see that the filament is not sticking to the previous layer and you are getting a rough surface (like the picture below), or you will get a part that is not strong and can be pulled apart easily.  In either case, you should increase the temperature by 5 degrees and try again until you get good line segments on every layer and have a strong part when done printing.

Extruded PLA 3D printing Filament Not Hot Enough temperature

Extruded Filament Not Hot Enough

Changing Filament

When switching PLA colors:

  1. While the extruder is cold set the heat to 120°C and wait for it to heat up.
  2. When you reach 90°C, start pulling on the filament until it finally gives out and pulls all of the filament from the nozzle in one long, stringy strand
    1. If you are having trouble removing the filament, it's okay to raise it to 200°C and deal with purging more filament to compensate.
  3. Increase the heat and load the new filament normally.
  4. Run the new color through the extruder until it runs clean and the new color is all that is coming out of the extruder. If you are switching from a dark color (such as black) to a light color (like white or natural) run a while longer to be sure you don't have any dark contamination.

What to do When Things go Wrong

There are a few key things to check when your prints aren't working.  But before we look at solutions we need to have a brief description of your symptoms.

"I can't get the first layer to stick."

  1. Make sure the nozzle is at the right height. Adjust the limit switch or raise/lower the bed to adjust the nozzle distance.
  2. Make sure the print bed is level. Level the bed

"The part has bad internal layers and top surfaces."

  1. Check the extrusion temperature (you may need to increase it in 5 degree increments)
  2. Check the filament tension.
  3. Clean the filament drive gear

"The outside edges of my parts have lots of little bumps on them."

  1. Make sure your printer is getting enough data. If printing from a computer, ensure that the computer is not too busy to feed the printer commands. If the printer is pausing it is usually due to the printer being too busy.
  2. Print from SD cardOn some printers you can try and print from SD card.  This often helps the printer have enough data to run more smoothly.
  3. Source better PLA.  We have found that the quality of your print material can have a big impact on the quality of your part.  Getting better PLA can help you get better parts.  However, don't be too quick to assume the problem is in your PLA.  With the right settings and patience hobbyists have succeeded in printing all sorts of materials many of which have very low viscosity and inconsistency.  You should be able to get at least usable parts even with some lower quality filament.

"Tall sections of my prints look melted or squished together."

  1. Turn on "Cooling". If your printer has a fan you should enable "cooling" in the print settings.
  2. Get a small fan. If your printer does not have an integrated fan you should look into getting a small desk fan.  This can help dramatically with tall sections of your print or when "bridging" (printing top layers that span gaps).

"My printer will not put out any material."

  1. Make sure your hot end is getting hot. Check that the hot end is heating at all.  If it is not you need to have your printer serviced.  It is likely that you have a loose connection or your electronics have been fried (assuming the printer is still connected and responding to your host software :).
  2. Clean the drive gear and adjust tension. The first thing we are going to do is clean the filament touching drive gear and ensure that we have proper tension against the filament.  Usually improper tension or a clogged drive gear will make the print look more like the picture we have for low temperature filament, but it sometimes does prevent extrusion all together.  Clean the pinch wheel with a wire brush, and make sure your tension is good and solid (too much can also prevent extrusion and is more common with direct drives [the motor is directly connected to the drive gear] but less common with geared drives).
  3. Remove the current filament. It may be that you have a small particle in your extruder tip jamming the plastic.  Use the change filament technique described above to pull out any particles that are in the extruder tip.
  4. Check for and remove jams between the extruder and hot end. This is the most extreme type of problem because now it is time to take things apart.  Sometimes heat can creep up the filament in the extruder and cause a bulge that then cools and prevents any further extrusion.  This is usually at the junction between the extruder and hot end.  Take off the extruder and remove all the PLA you can (you may need the hot end hot  (80c-100c) to get all the material out.  If you can't get out all the filament by pulling it out you may need to try and drive it down through the hot end. We usually use a small allen wrench.  If this fails you can try and drill out the extruder or hot end but you may need to replace parts.  Be sure to take precautions against being shocked or burned.  If you are not qualified to do this work find someone who is, rather than risk injury.

Thank you for reading How To Succeed When Printing In PLA.

If you have any comments or contributions, please drop us an email or give us a call. We are always looking for tips, and best practices - and would love to hear from you. Feel free to reach out with any specific questions on the MatterHackers Forum.

Happy Printing! - MatterHackers

P.S. Check out our Filament Comparison Guide to get the scoop on all the latest and greatest filaments! Or browse the MatterHackers Store for all your fun filament needs.