As PETG is one of the most popular filament types in 3D printing and glass is one of the most popular build surfaces, we can consider the combination of PETG and glass surfaces inevitable for most 3D printing enthusiasts.
While the primary complaint about the combination of glass and PETG often is that they stick too well to one another, there are also cases where the two don’t stick to each other due to certain conditions.
In today’s article, we will delve into the issue of PETG filament not sticking to glass bed in some scenarios, which definitely is a strange one, as PETG is supposed to stick very well to glass in an ordinary situation.
So, what can cause PETG to not stick to a glass bed?
As there are a few different culprits that can cause PETG to not stick to a glass bed, we have listed all the possibilities below:
- Print temperature too low
- Bed temperature too low
- Cooling speed too high
- Glass bed not level
- Glass bed not clean
Next up, we will be analyzing the topic of PETG not sticking to a glass bed in more detail, find out what we can do to fix this issue, and take a quick look at whether PETG prints well on glass or not.
Why Is My PETG Not Sticking to the Glass Bed?
As PETG is a material that naturally sticks very well to glass surfaces, PETG not sticking to a glass bed is definitely an anomaly, but fortunately, an explainable one.
To understand what could be causing PETG to not stick to the glass bed in your case, let’s start by going over all possible factors individually and in detail.
Low Nozzle Temperature
A nozzle temperature that is too low is a very common culprit that prevents PETG from sticking to a glass bed.
When the nozzle temperature is too low, PETG will cool down quicker than optimal once it touches the glass bed and solidifies before it has time to form strong bonds with the surface.
Low Bed Temperature
As the temperature of the glass bed is vital for the PETG to stick firmly, a low bed temperature is another factor that we need to keep in mind.
When the bed temperature is too low, similar to a low nozzle temperature, PETG will cool down way too quickly once it touches the glass bed, solidifying before it can adhere firmly enough to the surface.
High Cooling Speed
A high cooling speed creates a similar issue to a low bed or nozzle temperature by cooling the PETG too quickly before it can stick to the glass.
When the cooling speed is too high, the fans will cool the PETG down before it has sufficient time to adhere to the glass bed, which will cause the plastic to peel off the surface instead of sticking.
Glass Bed Not Level
A glass bed that isn’t level is problematic for the entirety of the 3D printing process, and it can easily prevent PETG from sticking to the surface correctly.
When the glass bed is not level, there will be areas where the distance between the build plate and the nozzle is too much, where the nozzle won’t be able to apply enough force to the plastic to secure it onto the glass bed.
Glass Bed Not Clean
A clean surface is paramount for bed adhesion, and a glass bed that isn’t clean will, without a doubt, prevent PETG from sticking to it.
When the glass bed is not clean, dust and oil that gathers on the surface will prevent the PETG from sticking firmly to it, as the build area needs to be entirely clean for the filament to adhere correctly to it.
How Do You Get PETG to Stick to Glass?
The primary way to get PETG to stick to glass, just as it should, is to find out what’s preventing it from sticking and apply the appropriate solution for that specific factor.
Below, we have listed all the solutions for the problems that can prevent PETG from sticking to the glass and some extra tips that will make it easier for PETG to stick to glass:
- Increase the nozzle temperature, preferably to the higher end of the manufacturer’s recommended temperature range.
- Increase the bed temperature, preferably to the higher end of the manufacturer’s recommended temperature range.
- Decrease the cooling fan speed, especially for the first layer.
- Level the glass bed, preferably with an auto bed leveling sensor, to obtain the bests results possible.
- Clean the glass bed thoroughly by wiping it with isopropyl alcohol.
- Use an adhesive on the glass bed, such as Windex, hair spray, or a glue stick to increase the adhesion strength between the PETG and the glass.
- Add brims and rafts to the model.
Does PETG Print Well on Glass?
A vital point to consider while printing with any filament type and build plate is whether the material prints well or not, as not every material and surface are compatible.
While it’s possible to get PETG to print well on glass by applying adhesives to the build surface and being careful about the configuration, PETG and glass aren’t the most optimal combination in 3D printing due to the naturally high strength of adhesion between the two.
To achieve the most optimal prints possible with PETG, we highly recommend investing in a powder-coated PEI sheet that you can quickly attach to or remove from your existing glass bed, as PEI offers the most balanced level of adhesion for PETG.
Seeing that your PETG isn’t sticking to glass can definitely be surprising, especially considering that the natural strength of adhesion between glass and PETG is pretty high, to an extent where it’s often hard to separate one from the other.
To quickly recap, we can split the primary reasons that can prevent PETG from sticking to glass into two categories of configuration-related issues and maintenance-related issues.
In the case of configuration-related issues, the main offenders are printing and bed temperatures that are too low and a cooling fan speed that is too high.
On the other hand, maintenance-related issues would be a glass bed that is not level and a glass bed that is not clean.