Why Is PLA Not Sticking to Glass Bed? (And How To Fix It?)

No matter how fun 3D printing is, the problems that come with it can be very annoying at times, especially if the problem completely ruins a print that you have been eagerly waiting to finish.

While we would all love it if we could press a single button and obtain a perfect print, there is no escaping from long troubleshooting sessions to make everything work as intended for now.

Today, we decided to talk about the widely known issue of PLA filament not sticking to the glass bed, a problem that troubles many 3D printing enthusiasts. As this problem completely prevents your 3D printer from printing, we understand how frustrating it is to wake up one day and face this issue.

So, why is PLA not sticking to the glass bed, and what should you do to fix it?

There could be a multitude of reasons behind PLA not sticking to the glass bed.

  • The glass bed is not clean.
  • The glass bed is not level.
  • The nozzle starts too close to the bed.
  • The nozzle starts too far from the bed.
  • The print speed is too high.
  • The first layer cools too fast.

As there are plenty of things that can go wrong to prevent PLA from sticking to the glass, fixing the problem requires finding out the culprit first.

Since finding the factor causing the issue can be challenging with so many variables at play, let’s get into greater detail about each of these factors and other symptoms that come with them to make it easier to pinpoint the root cause.

Why Is PLA Not Sticking to Glass?

As we have mentioned earlier, PLA not sticking to glass can be caused by various factors, which is why we will be speaking about all of these factors in great detail.

Dirty Printer Bed

Perhaps the most common cause of PLA not sticking to the glass bed is the bed not being clean.

While the bed may look clean from the outside, this often isn’t the case due to the level of cleanliness required for PLA to stick to glass healthily.

If you have used glue to make the filament stick to the bed before and gotten results from it, there is a good chance that your problem is the printer bed being dirty.

Printer Bed Not Level

Another one of the most common causes behind PLA not sticking to the glass bed is the bed not being level.

When the bed is not level, the vertical distance between the nozzle and the bed keeps changing as the nozzle moves. As a result, the filament may stick to some areas of the print bed but not the others.

If the filament is sticking to the bed in only some areas, if some parts of the bed block the nozzle from extruding, or if you notice height inconsistencies on your model, your printer bed is most likely not level.

Nozzle Too Close to the Bed

If the printer nozzle is too close to the bed, PLA may not stick to the glass bed.

For the extrusion process to proceed optimally, there should be a certain distance between the nozzle and the print bed for the plastic to come out as intended.

If this distance is shorter than optimal, the bed will block the filament from coming out of the nozzle, which often prevents the printer from extruding the first few layers of the model.

Nozzle Too Far from the Bed

Just as the nozzle being too close, the nozzle being too far can also cause PLA to not stick to the glass bed.

When the vertical distance between the nozzle and the printer bed is too large, the layers of filament will have trouble sticking to each other, eventually causing the model to collapse.

Alongside sticking-related issues, this problem usually causes a visible effect where filament lines have gaps between each other.

High Print Speed

A high print speed can prevent PLA from sticking to the glass bed properly.

When the nozzle moves way too fast, the plastic doesn’t get enough time to bond, often resulting in adhesion-related problems such as this.

If your print speed is too high, you will most likely also encounter problems such as deformation and artifacts on your prints.

Temperature Problems

While temperature problems are the least-encountered culprit for PLA not sticking, it’s still worth mentioning as the last factor on our list.

As you know, plastic starts shrinking when it starts cooling down. On the other hand, the bed that it’s stuck to stays at a constant temperature for the most part. As a result, the plastic slowly starts separating from the bed and eventually detaches completely.

If you encounter a scenario where your model initially sticks to the printer but eventually separates, it might be worth keeping an eye on the temperature settings.

How Do You Get PLA to Stick to Glass?

Now that we have analyzed the factors that can cause the issue, it’s time to talk about solutions.

While you can pick the step that applies to you if you are sure that you have pinpointed the problem, you can also follow the list from the start to the end if you are unsure.

  1. Clean the printer bed. Thoroughly clean the surface with either sterile alcohol pads or cotton with isopropyl alcohol on it. Ensure that there are no leftover materials on the printer bed, and refrain from touching the printer bed or putting items on it to keep it clean.
  2. Level the printer bed. Most printers come with an auto bed leveling feature that you can use to level the printer bed. If auto-leveling doesn’t work, you might have to spend some time manually leveling and experimenting.
  3. Configure the Z offset. Configuring the Z offset is necessary to ensure that the vertical distance between the bed and the nozzle is optimal. As most slicers have a setting for this, you should easily be able to experiment and find the correct value.
  4. Reduce print speed. Experiment with lower printing speeds to see if the problem is still taking place. As there is no set value for this, you can reduce the value in small increments until you see results.
  5. Reduce fan speed. Reducing the fan speed can slow the cooling of the first layer down and prevent it from separating from the bed. Most of the time, it’s enough to reduce the fan speed for the first few layers and put it back up to default later on.
  6. Apply adhesives. If nothing else works, you can apply adhesives such as painter’s tape, hairspray, or a glue stick. Using these materials will increase the adhesion of the bed and can help the filament to stick.

Do You Need Glue to Stick PLA on Glass?

While glue can help to make PLA stick on glass, it’s certainly not a necessity for things to work as intended.

If the PLA isn’t sticking to the glass bed without glue, whereas it works perfectly fine with it, the most likely culprit is the glass bed not being clean.

To clean the glass bed, wipe the surface thoroughly with sterile alcohol pads or a combination of isopropyl alcohol and cotton. While this isn’t something you have to do frequently, you can repeat it as soon as you have sticking-related problems again.

Finally, to keep the surface clean, make sure to clean any leftover material off the printer bed as soon as the printing process is over.

Wrapping Up

While PLA not sticking to the glass bed can cause a high degree of frustration due to the amount of troubleshooting it requires and due to it instantly ruining any print, fixing the problem isn’t too challenging once you find the root cause.

As the most commonly encountered culprits are either related to bed leveling or the bed not being clean, solving the problem usually doesn’t take more than 5 minutes when the correct steps are applied.

Happy printing!