PETG is one of the most popular filament materials among hobbyists, professionals, and engineers.
The modified version of PET is being used in many products like plastic bottles, car accessories, and even 3d printer parts due to its high chemical resistance. PETG is a variant of PET, so as you may expect, PETG is hard to dissolve.
What does dissolve PETG?
Dichloromethane, toluene, cyclohexanone, and methyl ethyl ketone (MEK) are the most common solvents for PETG. They are useful and less dangerous to use and store compared to other options. However, they are still toxic and strictly regulated for various reasons.
Dichloromethane is a CLP volatile carcinogen and can quickly vaporize into the air. Toluene is a significant and common component used in explosives, so it is not easy to find and buy. Cyclohexanone and MEK are also considered predecessors in the production of illegal drugs and are also regulated.
These named solvents are not recommended nor easy to buy. However, there are other alternatives ways you can use to deal with PETG, whether you want to remove it from a surface or smooth it. We will further discuss this topic down below.
How to remove PETG from the bed without dissolving it?
The best option is to use a sharp, flat object like a palette knife and alcohol. After your 3d printer finished the work, start pouring alcohol between the printer’s bed and the part. Next, try to put a palette knife beneath the print and start removing it from the bed. Be extra patient and use the knife delicately to remove it smoothly.
Another good idea is to use different temperatures and different material properties of PETG and 3D printer’s bed. As you may know, heated beds form stronger bonds with hot filaments. After the print has finished, the first action is to let the bed and the printed part cool together. In this case, there is a chance for the print to pop off automatically.
To take more advantage of this behavior, you can use extreme temperatures. For example, use a canned CO2 to cool down your print uniformly. You can also put the printed part and the printer’s bed into the fridge for about an hour. This technique usually yields good results.
How to clean my extruder after printing with PETG filament?
You can take off the nozzle and heat it with a torch until the filament melts and comes out; that simple! However, there are more options. You can also take a brass brush and clean the nozzle with it.
You can also use a metal wire or even a nylon filament to clean the nozzle’s hole. If none of these options worked, and you have a 0.4mm nozzle, you could use a 0.4 mm drill bit to clean up the nozzle, but you should be aware that you risk damaging your nozzle in this scenario.
How to smooth PETG with heat treatment?
Heat treatment of PETG is intensive but possible. To do it correctly, you need to use hot air stations with temperature controls. The recommended temperature for the heat treatment of PETG is around 230o C, and it melts around 260o C. So you’re going to need to be careful about it.
PETG smoothing with hot air stations needs a delicate and continuous motion to reach the desired surface. So, suppose you don’t have enough experience working with a heated g; in that case, it is recommended to lower its temperature to around 220o C so that you won’t melt the printed part.
Get back to the basics, Sanding!
Another method to smooth PETG is to sand it. Sanding PETG can be a little more complicated than sanding PLA prints. The process is pretty similar but a little more time-consuming.
Start sanding with the coarsest sandpaper you have (but no less than 200). After removing apparent layers, it is time to use your set of sandpapers with grit sizes ranging from coarsest to finest. A girt size around 400 is more than enough to start. Whenever the first result was satisfactory, you can change the sandpaper with a smoother one. You should do the process with sandpapers of various sizes if you want an excellent finish.
While sanding the part, your hand should have a circular motion so that a directional bias does not make straight visible lines. Sanding can become much faster if you use a wet sanding method.
Wet sanding uses slightly wet sandpaper to mobilize free particles away from the outer surface. However, it is a necessity to use high-quality sandpapers that are also waterproof. In this case, I recommend 3M Wetordy Sandpaper Set.
Another option for better smoothing PETG is to use an appropriate polishing compound after sanding your part. It is hard to remove small layer lines by just using sandpapers. If you want a perfected surface, you also need to fill the gaps between layers with a polishing compound.
To start the process, bring a piece of cotton cloth, and apply some compound to it. Now you can begin to rub it to the printed part. The rubbing motion should be the same as the sanding circular motion with enough pressure. In this stage, the compound fills the gaps, and it’s time to remove the extra polishing compound with a piece of dry and clean cloth that has not been treated with the compound.
You can repeat this process several times, and the improvements in the finished surface will become more apparent. Don’t underestimate it; You can have a mirror-like finish just by sanding and polishing.
In this case, I recommend using a wax-based solid finishing compound like Polishing and Buffing Compound from BeaverCraft or a metal polish solution such as 3D One Polishing Finishing Compound.