Learning to paint your 3D printed parts will enable you to create looks-like prototypes, detailed miniatures, and a variety of other visually accurate models. Navigating the various different materials and techniques can be intimidating, and in this post you’ll learn all of the steps needed to paint your parts from start to finish.
Starting with a detailed and well-printed model will make the rest of the painting process easier and improve your final results. Resin printers like the Formlabs Form 2 are best for painted parts, both because of the high resolution and the ability to use some paints directly on the printed surface.
Preparing Your Model for Painting
Your printed model should be smooth and devoid of artifacts prior to painting. For SLA 3D printers, this involves removing the support structures and sanding down the support nubs. To remove the nubs, start with a coarse sandpaper of around 100 grit and work up to at least 200 grit. This will ensure that scratches don’t show up in your painted model.
For FDM printers with large layer heights, sanding the entire model might be necessary prior to painting to make certain that that the layering isn’t visible. A heavy primer can be used as an alternative to sanding, though this might obscure any intricate details in your part.
Primers serve as an intermediary layer between your printed part and paints. They smooth out artifacts in your model, provide a bonding surface for paint, and create a consistent finish.
Before priming your part, identify any features that you won’t be painting and cover these. This process is known as masking, and several mediums can be used to cover your parts. The most common is painter’s tape, which can be cut and shaped to your geometries. Masking paints are also available which are brushed on and then manually removed after use.
A wide variety of primers exist, and which you choose will depend on your part properties and the paints you’re using. Primers come in a number of different weights: light primers go on as thin coats and will provide a smooth surface for painting but won’t mask scratches and artifacts in your part, while heavy primers are thicker and are a good choice for large parts that lack intricate details.
Your primer must be compatible with both the material of your printed part and your paints. Many common primers will be labeled as “plastics compatible,” and these tend to be suitable for most 3D printing materials. Common paints like acrylics and enamels will be compatible with most primers.
Primers exist in both spray-on and brush-on options. Which you use will depend on your specific application, and a common workflow is to use a spray on primer for the majority of your model and then touch up with a brush-on material.
The Base Coat
Intricate parts are often painted in several layers, starting with a base coat and progressing to higher levels of detail. The base coat is brushed on and then details are added later in the process.
The most common types of paints, and the ones that work best with most primers, are acrylics and enamels. Acrylics are water-based paints with a variety of different surface finishes, and enamels are solvent-based with predominantly glossy finishes.
To apply fine details on top of your base layer, you’ll need one or more paint brushes. Brushes come in a number of shapes, sizes, and materials, so many beginners will opt to purchase a kit to cover all their bases. Miniatures often focus on thin liner brushes designed to be small enough to accurately apply fine details. Larger parts may benefit from flat or round brushes capable of quickly covering large surfaces.
Gather your materials, and get started by painting an even base coat. Don’t worry too much about intricate details here, as we’ll work on those later in the tutorial. If you mess up, grab a damp cloth and remove the paint as best you can. Any residue can be cleaned up later during the more detailed stages. We’re painting The Entangler by Designer Gokcen Yuksek, and using an acrylic paint for the base coat.
We split this model into several main components, chose a color scheme for each one, and applied the primary color of each as a base coat. Models that are split into multiple pieces like The Entangler make this process simpler, as we don’t need to worry as much about paint getting on unintended surfaces.
The base coat provides the foundation for your painted model, and a variety of techniques can be used to bring out more intricate details. Using a fine liner brush is an option for resolving fine details, but often techniques like washing and dry brushing can provide a better finish in less time.
Dry brushing involves the use of a mostly dry and often stiff brush to paint positive surfaces. We’ll be using a dry brushing technique for the fishnet stockings on The Entangler instead of manually painting each of the lines with a fine brush.
Apply thick paint to a dry brush and aim for light to medium saturation of the brush. This technique is being used to paint positive surfaces, and too much paint may drip onto the negative, indented surfaces. If there’s a bit too much paint on your brush, test it on a smooth surface until it produces a thin and lightly textured stroke.
You’ll want to keep the pressure between your brush and part low when using this technique. We’re lightly dry brushing over the stockings to highlight the netting while avoiding the surfaces below.
Dry brushing can also be used to add texturing to your models. Aim for the same light coat of paint on your brush, and then experiment with different pressures to vary the finish on your part. This is best for creating a rough and grainy texture and, as a result, isn’t often used for applying solid base coats to a part.
Dry brushing is great for highlighting positive surfaces, while washing is ideal for painting negative or indented features in your part. Washing involves heavily diluting your paints, such that they’re thin with low viscosity. Acrylic paints are often diluted with water, while enamel paints are diluted using solvents. Check your specific product for dilution instructions, as this can vary for specific formulations.
Once you’ve diluted your paint, brush it over the entirety of the surface you’re looking to highlight. Then, immediately use a cloth or towel to remove paint from unintended features. We used this technique on both the dress and boots of The Entangler. Washing is a great technique for painting hard-to-reach indented surfaces in a model, and it also highlights positive features, since the color will “frame” any positive area where the wash has been wiped off and give your model a crisp 3D “pop”
Creating a Marble Texture
For The Entangler’s base platform, we used a more advanced painting technique called marbling. To achieve this texture, identify the colors that will be included in your finish — you probably don’t want more than three — then paint on streaks of the first color. This shouldn’t cover the entire part, as you’ll want to leave some space for additional colors. Next, paint uncovered regions with your second color, allowing it to overlap with the first in some regions. Think of it as painting loose, abstract stripes on your model, and allowing those stripes to blend.
Once your paints are applied, wet a clean brush or clean rag and use it to blend the two colors together. This process must be done quickly, as the paints won’t blend together properly once they dry.
Stippling is another great technique for adding additional spotty textures to your part. This involves depositing small droplets of paint on your part–droplets that can either be kept distinct or smeared with other colors to create a diverse texture.
We’re using stippling to add more texture to the marble base. A variety of tools can be used for this technique, but one of the most widely available is a common toothbrush. Dilute your paint such that the viscosity is near that of water, and dip the bristles of your toothbrush. From here, run your finger along the bristles to spray small droplets of various sizes onto the surface of the part. Keep these as is, or add a bit of water to your part to begin blending the droplets together.
Painting is an expansive discipline that involves a wide variety of tools and materials, and each paint job presents a different set of challenges This tutorial arms you with some powerful techniques for meeting these challenges, and painting any part you might print. There are countless more techniques than what we’ve covered here–please comment with your favorites below!