You’ve found the perfect model to print, and your 3D printer has done a great job – but something’s missing. Prints fresh off the print bed are hardly ever showroom-ready.
Be it those pesky layer lines, clingy support material, or flat-out ugly printer artifacts, the surface of your 3D print is likely to need some attention. Post-processing techniques do just that and can take your print the final mile. While there are a lot of fancy techniques out there involving chemical smoothing, sanding, dipping, and plating, a good old-fashioned paint job is hard to beat when it comes to making your 3D prints look shiny and polished. Plus, who doesn’t love a splash of color?
Keep in mind that it’s not as simple as merely applying a coat of paint to your freshly printed model, and that some prep work will be involved. Paint hides no flaws, so support marks and small blemishes will show through the surface unless you take the time to sand and apply a coat of primer before painting.
In this guide, we cover the basics of painting PLA and ABS 3D prints, from smoothing to the actual painting process, while providing some helpful tips in between, such as the best paint to use. Here, we opt for spray painting over the use of a brush or airbrush because it’s less laborious and fairly affordable as will be explained later.
Now, let’s get artsy!
Paints can fall into various categories based on their solvent. The most common ones are oils, enamels, lacquers, and acrylics, most of which will work well with both ABS and PLA. As a newbie, you’d be wise to stick to acrylic paints since they dry fast and can be cleaned with water.
Usually, you have to decide whether you’re going to use an airbrush, a brush, or canned spray paint. While a brush is cheaper compared to the other options, it can be tough to accomplish an even coat of paint, with noticeable blobs in some spots and the underlying color appearing in others. An airbrush, on the other hand, is costly and typically has a steep learning curve.
This leaves us with spray paints, which strike a balance between affordability and ease of use.
Smooth and polished prints start with sanding. Here’s how to get started:
This is considered the first stage, and it involves trimming rough print features, such as support stubs, before sanding.
You can use some of the following materials in this stage:
The key is to eliminate any protrusions and make sure the print is clean. You can peel off supports with your bare hands or you can use a knife. It doesn’t matter, as long as the final result doesn’t have bumps or protrusions. And no matter how you’re removing supports, be careful! It’s not just about the sharpness of the blade or tweezers but also about where flying fragments may go.
Begin with 120-grit sandpaper and work your way up. The higher the grit number, the finer the sandpaper. Use circular motions to avoid visible scratches, and pay more attention to the sides while avoiding the edges, corners, and any other fine details. After all, 120 grit can be too strong for small details.
Sanding smooths deformities and can be time-consuming depending on the size of the print or finish you’re aiming for. Sand down the support marks and make sure you’ve removed any filing or tooling marks.
Progress through the grits depending on your print, but once you’re finished with 200 grit, start using water. This prevents clogging and gives a finer finish.
While sanding, feel the surface of the print at intervals to get an idea of how smooth it is. Once the smoothness is to your liking, use a brush and water to wash away any trapped dust. Naturally, you’ll want to let the print dry before moving on to the next steps.
Check out our beginners’ guide to smoothing PLA if you want to get into the gritty details on this process.
Priming turns your 3D print into a professional product and makes the painting process effortless by creating a flawless final surface. Priming is necessary because paints will never hide all the flaws, especially when you’re aiming for a near-perfect object.
Go for a primer that’s compatible with your plastic. We prefer using a spray-on primer because it can quickly cover the entire surface with an even coating. This is different from brush-on primers, which are better for fine touch-ups.
Allow your primer to dry before adding extra layers. Usually, two layers are sufficient for a clean surface finish.
The first two coats should be very light since we’re only using them to improve adhesion for the successive layers. Since a primer is enough to improve the surface finish and the aesthetic of the printed part, some people choose to use a primer without even doing any additional painting.
After your final primer coat is added, your part is now ready for painting.
At this point, you should have a mental image of the finish you’re trying to achieve. The painting process is quite similar to priming.
You’ll need the following materials:
Let the paint dry overnight, then clean the part the next day using a tack cloth.
As you’re painting, the following are some things to keep in mind:
Below are some general pieces of advice to enhance the above steps:
Painting shouldn’t just be an afterthought – think about it as early as the design stage. It’s best to experiment to find what works best for you because there are so many different effects you can achieve.
Happy painting!
License: The text of "Painting PLA: How to Paint 3D Prints" by All3DP is licensed under a Creative Commons Attribution 4.0 International License.