Turning Plastic Into Metal: Electroplating 3D Prints
Electroplating can give your 3D printed parts a beautiful metallic finish and yield metal-like properties, such as improved conductivity. This guide covers everything you need to know about plating prints.
There are a wide variety of options for finishing your prints. For some applications, a quick sand and spray finish may be fine, but for parts intended for use in electronic applications or armor, jewelry, and costume accessory prints, electroplating may be the best option.
In this article, we cover various electroplating processes and what you need to know to DIY your own metal-like 3D prints.
What is electroplating?
It isn’t quite transmutation, despite what the title may indicate, but electroplating does allow for a real metal layer to be developed on the surface of another material. Electroplating is by far the most common method by which metal is plated onto materials such as plastic, glass, and even other lower-grade metals. Simply, a part is electroplated by immersing it in a water and metal salts bath that is subjected to an electrical current. Parts are subjected to a chemical preparation process called etching to promote adhesion of the metal. This electrochemical process yields a thin, firm metal coating along the outer layer.
This process can be tweaked for different materials and applications. For instance, parts intended for heavy-duty use or long-term application in electronics are typically dipped in a special preparation bath that improves adhesion of the final metal plating and submerged in the electroplating solution multiple times to build up the outer layer. In these industrial applications, an “electroless” plating process is often performed, which generates a thin metal coating without electricity using a heat bath, to prime the part for good adhesion.
Electroplating can be performed with a variety of metals. An inexpensive metal is often used for the first layer, particularly in industrial electroless plating, but almost any common metal can be plated on top of that layer.
The types of metals used for electroplating are selected depending on the intended application and desired aesthetic of the final piece:
- Copper: Owing to its high conductivity, copper is widely applied for parts intended for use in electric and heat transfer applications. When polished, it can also produce a good aesthetic. Copper is notoriously vulnerable to wear and elemental damage compared to other metals.
- Nickel: Commonly used to produce a silver-like sheen for jewelry and cosmetic parts, nickel is a good choice for minimal-wear prints. Owing to its porosity, it is less likely to hold up well to heavy use and corrosion without maintenance.
- Silver: This metal is widely applied for aesthetically pleasing parts that require good conductivity. Though pricier than other metals, it can be a good option for some jewelry or decorative prints such as 3D printed statuettes. Like solid silver, electroplated silver can still tarnish.
- Gold: As a highly resistant material to corrosion and oxidation, gold makes an excellent protective coating for a variety of parts while conferring a beautiful finish. Hobbyists typically do not work with gold owing to its higher price.
- Chrome: This metal is widely used in automotive and other industrial plating applications for its clean, aesthetically pleasing finish that is corrosion- and abrasion-resistant. While it is technically possible to electroplate chrome at home, the process is highly nuanced and expensive, so it is best left to professionals.
Problems associated with electroplating
Because electroplating requires that the maker takes special care to achieve a good electrochemical environment, there are many things that can go wrong.
During both electroless and electroplating processes, there is some risk of warping, particularly for highly thermally sensitive materials. Additionally, the chemical composition of the etchant can cause warping or “melting” in some plastics.
Roughness and poor finish
If the area in which electroplating was performed was not completely clean and free of debris and dust, there is a risk of this debris getting trapped in the plating, causing a rough and uneven finished texture.
Plating and adhesion failure
Sometimes, adhesion can fail on certain portions of the print or the entire part depending on whether etching was performed properly and whether the speed of acceleration was maintained for the size of the part.
These types of issues indicate that there is a non-negligible risk for issues to arise during any process, much less when undertaken by a beginner at home. Though electroplating your own prints is not for the faint-hearted, it can achieve wonderful results for functional electronic prints and bring your armor pieces to the next level.
Before you dive into electroplating that Mandalorian helmet you just pulled off the print bed, let’s review the electroplating process:
- Bath immersion
As discussed earlier, most industrial applications apply an etching and electroless pre-plating method to prepare plastics for electroplating. While there are ways to perform these processes at home, they can be a bit overkill. Instead, all you need to do is prime the part with a conductive material that will allow the metal film to develop on the outer layer. Most makers use a conductive nickel spray coating or conductive graphene paint to prepare their 3D prints. Either works—simply pick an inexpensive material that can easily cover all the nooks and crannies of your print evenly.
Carefully clean your 3D printed part to remove any residues, dust, and debris. If your print is notably uneven, we recommend sanding down the print to achieve a relatively smooth finish. It is okay if it isn’t perfect at this stage as there will be a few more rounds of sanding to come. Stick with your lower grits in this stage to buff out any large dents or layering.
After your print is clean, use your conductive primer of choice and ensure that you evenly coat the part. Any portion of the print that is not coated will not develop a metal coating, so take care to achieve a good coating per the manufacturer’s instructions. After the conductive layer has cured (usually within 12 to 24 hours), use higher-grit sandpaper (400 and above) to gently buff the conductive coating, being very careful to not remove too much material. This will lessen the need for post-processing after plating, conferring a cleaner and shinier finish.
While most electroplating processes require a submersion bath, there are an increasing number of “brush” style kits on the market for large or detailed applications. We will not go into detail here about buying pre-made kits vs. assembling your own, but the latter may be a good investment if you plan on electroplating often. Brush kits are preferred by makers working on helmets and other pieces with larger, flat, or gently curved surfaces, while immersion baths are best for smaller parts. Once you have selected the metal you want to work with, look at the reviews and results for various kits to find the size and style that works best for you.
For the brush kits, the alligator clips that conduct the electric current will be placed directly on the print. For submersion kits, they will be placed on a conductive element that sits inside the wash basin to send a current through the metal salts bath. Regardless of the style you use, it is critical to be very careful. Work on a clean, open, and organized surface. Make sure you can see all labels for the materials you are working with. We strongly recommend wearing chemically resistant gloves and only using these chemicals in a well-ventilated area.
After plating your print, an even nicer finish can be obtained by cleaning and polishing the metal layer.
Some electroplated parts can be very gently sanded and polished using high grit sandpaper and polishing blocks, but this may remove more material than you anticipated if you are just getting started with this process. A safer bet is to use a metal polish typically marketed for copper, brass, nickel, and aluminum, with a dedicated polishing rag and microfiber cloths to clean the final product.
After getting the finish you want, you are ready to use, wear, or mount your metal-plated print! If you want to protect the shine longer, we recommend using a clear acrylic enamel coating to seal the print. An initial investment into a good electroplating kit will typically last for many applications, making it a great option for those who routinely make armor pieces or who sell wearable parts.
The helmets shown in the cover photo were printed and plated by Reddit user Grindeddown.