Can You Print PETG on a Glass Print Bed? Explained

Whenever you plan on printing with a new type of filament for the very first time, one of the vital steps you should take to ensure that you don’t experience problems regarding bed adhesion is to confirm that the filament you’re printing plays well with the build surface you’re using, as it’s entirely possible to stumble upon combination that can either lead to the print not sticking to the build surface at all or get stuck completely, with both cases being highly problematic.

In this article, we will discuss whether the combination of PETG filament and a glass print bed is feasible, take you through some tips and tricks that will help you print successfully with PETG on a glass bed, and look at ways of removing PETG safely from a glass bed in cases where the material gets stuck to the surface.

Can You Print PETG on a Glass Print Bed?

Since PETG is a type of material that sticks extremely well to a glass print bed to the point where it can become pretty challenging, or even impossible, to separate the PETG from the glass without causing damage, whether it’s the printed part itself or some residue that gathers on the surface after the print, printing PETG on a glass print bed is something we don’t really recommend due to it being highly likely for you to also come across such a scenario.

residue stuck to glass print bed example
Source: X Builder @ Stack Exchange (CC BY-NC-SA 4.0)

While it can be tempting to try things out for yourself if it’s your first time printing with PETG, with no other option except a glass print bed available to you at the moment, going ahead with the print without taking the necessary measures (which we will discuss in the upcoming section) to protect your glass bed and make it more feasible for printing PETG can easıly result in permanent damage to the surface of your glass bed, along with a waste of both filament and time on a print that won’t come off.

With this in mind, the best way to move forward if you will be frequently printing PETG would be to pick up a separate build surface that’s more suitable for the task, such as a textured PEI sheet, which you can use to quickly replace your glass print bed whenever you’re printing PETG, and solve the problem in a convenient and straightforward manner while leaving your glass bed ready for printing with a different type of filament.

On the other hand, if that’s not something you’re considering for the time being, our recommendation would be to check out the following section, where we will discuss ways to make it possible to print PETG on a glass bed successfully without putting the print bed at risk of permanent damage.

Tips & Tricks for Successfully Printing PETG on a Glass Bed

Even though a glass print bed is definitely not a feasible option for printing PETG, there are a few methods you can employ to make things work while also protecting your print bed from damage, and while these methods are usually less convenient than using a suitable build surface from the get-go, they can come in quite handy in cases where you need to print your PETG in a pinch and can’t obtain a suitable build surface in time, or don’t plan on printing PETG too frequently.

When it comes to successfully printing PETG on a glass bed, our primary recommendation would be to coat the surface of the print bed entirely with either blue painter’s tape (cheaper, easier to apply and remove) or Kapton tape (Polyimide tape) (requires replacement less frequently, more durable, more resistant to higher temperatures) which will effectively create another layer that PETG will adhere optimally to on top of your glass bed, both solving the adhesion problem and also protecting your glass bed at the same time with no risk of permanent damage to it by entirely preventing it from coming into contact with the PETG.

While there will be some work involved with applying the tape correctly, whether it’s ensuring that there are no gaps or overlap, not touching the top surface with your bare hands to avoid contaminating it, or getting rid of any air bubbles between the tape and the print bed, we can consider this method to be the closest alternative to a permanent solution, as it will fully isolate your glass bed as if you were using an entirely different build surface, and only require re-application after a multitude of prints provided that you have treated the tape well.

On the other hand, in cases where you don’t have access to the necessary materials for the first method, another technique you can utilize to print PETG successfully on your glass bed is to apply a release agent, such as Windex (recommended), glue stick, or hairspray, which will temporarily act as a separator between the glass bed and your PETG print, and allow your prints to come off the glass bed conveniently and without risk as if you weren’t printing on PETG on glass at all.

Even though this method is much more straightforward to apply, as there isn’t much precision or care required in this case (making sure to use a generous amount of material and covering the entirety of the build surface is all there’s to it), the downsides of this method are that some of the materials used (especially hairspray and glue stick) can create quite a mess, the effectiveness of the material can be inconsistent based on the exact product you’re using, and more frequent cleaning & re-application depending on usage will be necessary to both ensure that your print bed is protected and the adhesion doesn’t become weaker.

How to Safely Remove PETG Prints / Residue Stuck to Glass Bed?

While safely removing PETG from your glass print bed can seem impossible in some cases due to how well the two stick to each other, especially when you also want to avoid damaging the printed part, there are some ways to save both your print and your glass bed without a scratch from this sticky situation.

In the case of removing a PETG print from your glass bed without damage to either the printed part or the print bed, the very first step we recommend taking is to place the print bed along with the print stuck to it into the freezer for roughly 30 minutes to an hour after it has cooled down to room temperature (important!), which should cause the glass to shrink and weaken the strength of adhesion between the printed part and the print bed to the point where you should be easily able to slowly release the print off the surface with the help of a plastic spatula (refrain from using brute force if it doesn’t come off), or even by just pulling the print off with your hands.

If the freezer method doesn’t resolve things, the following method you can utilize for the task is to apply some isopropyl alcohol along the edges of your printed part where it connects to the glass bed and wait a few minutes (once again, it’s crucial that everything has cooled down to room temperature for safety reasons first), which should soften the PETG, weaken the bonds that your part has with the print bed, and make it easier for you to pop the print off by applying some light pressure with a plastic spatula from all angles.

Provided that you still can’t get the print to budge, another method that can allow you to remove your PETG print from your glass bed safely is to place the glass bed back on your printer and heat the build plate up to the temperature you’ve used for the print, which should soften the PETG and make it possible to get the print off the build plate by slowly scraping it, once again with the help of a plastic spatula to avoid scratching the glass.

While there are many other methods you can use for the task, especially in cases where nothing seems to be working, whether it’s utilizing a heat gun to soften the PETG at higher temperatures or applying more force with a razor scraper, our recommendation would be to refrain from such methods unless you have experience, as these methods can be unsafe for both you and your glass bed unless you take the necessary safety precautions first.

On the other hand, when it comes to removing leftover PETG residue from your glass bed, the first step we recommend taking is to wipe the surface thoroughly by using some isopropyl alcohol and a paper towel, scraping the residue off with the help of a plastic spatula afterward, and repeating this process until it has no effect anymore, which, in most cases, should get rid of most of the residue without issues.

Once that’s done, the following step we recommend taking is to prepare a mixture of warm water & dish soap, wipe the surface of your glass bed thoroughly with a washcloth dampened with the soapy water mixture, and keep scraping any remaining residue with a plastic spatula at the same time, which should further help cleaning all the PETG residue off your glass bed.

Finally, once all the residue is gone, dry your print bed with the help of a paper towel (avoid touching the surface of the print bed with your bare hands), which should make it ready for your next print.

On the other hand, in cases where the residue still won’t come off, one last method we recommend using is to heat the bed to a point above the glass transition temperature (100°C should do) of the PETG by using the bed heating of your 3D printer to soften it to a point where it deforms and to use a putty knife to scrape any residue off the surface, and while this will come in handy in cases where the residue is stubborn, you can end up scratching the surface of your print bed if you aren’t careful.

Finally, while there are more potent methods available for this task as well, such as using a sharp razor blade to scrape the residue off, which can become necessary if nothing seems to be working, we would highly recommend refraining from using such methods unless you are fully capable of ensuring your own safety and accept that you can end up permanently damaging your glass bed.

Conclusion

While printing PETG directly on a glass bed is a no-go due to how well PETG can stick to glass and create a situation where your print becomes inseparable from the build surface, which usually makes it a better idea to switch to a more compatible build surface (such as textured PEI) if you will be printing PETG frequently, it’s definitely not impossible to make your glass bed more PETG-compatible by covering it with different material and effectively preventing the PETG from coming into contact with glass.

With that said, even though having printed PETG on your glass print bed is not a good position to be in, it’s not an impossible situation to get out of either, as there are a fair few things you can try to separate the PETG from the glass and save your print bed from permanent damage that would otherwise render it unusable.