The Best Methods for PETG Filament Smoothing
PETG filament is one of the most popular materials for 3D printing, second only to PLA filament. PETG is often used when you need a bit of extra strength to your part, but is also great for cosmetic pieces as well. When creating cosmetic pieces, smoothing out layer lines can be desirable. Here are some ways of smoothing your PETG prints for the nicest finish.
PETG takes very well to sanding, much better than PLA. Because PETG has a higher melting temperature than PLA, it doesn't get "gummy" like PLA does when it's sanded. You can start with a rougher, low-grit sandpaper and progressively work up to higher grits to get the finish as smooth as you'd like.
2. Resin Coating
PETG parts can be coated with epoxy resins. There are many resins available, including ones that are specifically formulated for smoothing 3D printed parts. Follow the manufacturer's instructions and you'll be able to get a smooth, shiny finish on any 3D printed piece.
3. Heat treating
Using a heat gun is an option for smoothing 3D printed PETG parts. However, special care must be taken to avoid melting and deforming the part itself.
4. Chemical smoothing
ABS is generally the filament used when chemical smoothing is desired, as it is easily smoothed with acetone, which is easily available. PETG is more difficult to dissolve with solvents, and only specialty chemicals can be used to smooth it. These include, ethyl acetate, methyl ethyl ketone (MEK), dichloromethane (DCM) and toluene. Always follow proper safety precautions when handling hazardous chemicals. Using them is at your own risk.
Also, not all solvents work with all formulations of PETG, some experimentation may be required.