PETG is a trendy 3D printing material, thanks to its strength, flexibility, and durability. These properties make PETG a great material choice for functional parts. If those parts are going to be visible, however, you may want to improve their appearance by smoothing them after printing.
Smoothing is a process that removes layer lines and other imperfections in a print, making it great for achieving a more visually appealing part. Try to avoid smoothing parts with fine details, as this can damage or obliterate them if you’re not careful enough.
Sanding is generally the first step in smoothing most filament types, and PETG is no different. It’s best to start with low grit sandpaper and progress to higher grits as you go. It’s best to use wet/dry sandpaper, usually distinguished by a black grit, as you can wet this with water which helps to clean the surface of the dust as you go.
Adding water also can help to keep the dust from becoming airborne and then being inhaled. Sanding can be incredibly time-consuming on larger prints and can be fiddly with more fragile parts. You should avoid using power tools as these are harder to control and can damage the print.
Once you’ve sanded your print, applying a polishing compound is a good way of getting a smooth surface. You will need to sand the print, however, as polishes won’t stick well if you’ve not used high grit sandpaper.
Liquid metal polishes are generally recommended as they are compatible with most brands of PETG filament. Pour a small amount of polish onto a soft cleaning cloth and then rub the entirety of the print. You may need to apply a fair amount of force to make polish difficult to apply to fragile parts.
Coating the print is another option to smooth it that doesn’t require sanding. Epoxy resin is a popular choice, especially self-leveling ones, as they flow smoothly, making them better at hiding brush marks.
Heat treatment with a heat gun is an option. However, it is quite difficult and risky. The goal is to heat it up enough that the surface starts to melt. If you get this just right, it eliminates the layer lines without properly melting the print.
It’s important to look up the filament manufacturer’s right temperature and keep the heat gun moving. Keeping the heat gun on one spot will irreparably damage the print very quickly.
While acetone mist smoothing may work on some filaments, acetone can’t dissolve PETG. Unfortunately, most chemicals that can dissolve PETG are dangerously toxic, often requiring special permission to purchase and expert knowledge to use safely. Ethyl acetate is one of the most common and safest options, but it doesn’t work on all PETG brands.
Hopefully, these tips help you to find a way you’re comfortable to smooth your PETG prints. If you’ve got any other tips for smoothing PETG prints, let us know down below.