Custom keycaps and aftermarket key sets are a fun and easy way to customize your keyboard. Most mechanical keyboards have keycaps that can be removed with a simple keycap puller tool. But Why would you want to replace your keycaps anyway? Lots of reasons.
Eventually keycaps made of cheaper materials will begin to wear out. This usually involves yellowing, losing their texture and having the legends fade or even completely disappear. Mechanical keyboards are generally very sturdy, but the keycaps will endure heavy abuse over the years. Just because the keycaps have outlived their effectiveness doesn’t mean the keyboard is ruined.
Restoring a well used keyboard to gain improved performance and increase its life expectancy is one valid reason to replace keycaps. Mods and customizations are another. Many in the mechanical keyboard enthusiasts community are keen on “pimping” their keyboards. You can even buy novelty or artisan keycaps with custom legends or shapes (often in the form of pop culture icons) that really stand out from the crowd.
Before going out and buying a full set of custom keycaps there are a few things to consider.
Keycap Materials: ABS vs PBT
ABS (Acrylonitrile Butadiene Styrene) and PBT (Polybutylene Terephthalate) are the two most common materials used to manufacture replacement and custom keycaps for mechanical keyboards. ABS is the cheaper build material found in budget keycaps. ABS keycaps are easy to manufacture because the material is less prone to shrinkage and easy to mold. This also makes ABS ideal for double-shot molding for extra durable legends that will not fade. ABS keycaps are highly resilient and less prone to shattering from impacts. One of the biggest drawbacks to ABS is yellowing, which keycaps made from ABS are prone to do. They’re also quick to lose their texture and begin to “shine” from the keycap surface becoming smooth. This results in a glossy looking key with less traction.
PBT is a premium material usually only found on higher end mechanical keyboards. PBT has a higher hardness factor and is more resistant to high temperatures and chemicals than ABS. One of the biggest advantages PBT has over ABS is it doesn’t yellow. PBT keycaps are extremely durable. They have a heavier textured feel compared to ABS keycaps that isn’t quick to wear down. The properties of PBT that make it a good keycap material also make it very difficult and costly to mold. For this reason PBT keycaps are less common and usually much more expensive.
Legend Labeling Methods
The type of legend (characters displayed on a keycap) applied to the keycap is critical if you’re not planning to use a blank keyset. The four primary methods are pad printing, double-shot molding, laser printing, and dye-sublimation.
The most common and least expensive labeling method that is easy to implement. Literally uses a pad and ink/paint to print a character. This is how the legends are applied to most low budget keycaps. Not very durable and the printed character is slightly raised, changing the keycaps feel. Pad printed legends are prone to fading over time with moderate use.
Using a laser beam to etch or engrave into the keycap material. More durable than pad printing since the legend is “charred” into the keycap, but still susceptible to fading as the keycap surface wears. This method traditionally produces low contrast legends as the engraved portion of the keycap generally has a dark grey appearance.
Extra work is involved to create a colored legend using laser printing. Usually a paint or ink (known as infill) is added into the grooves produced from the laser etching process. Often used for backlit keycaps in which a translucent material is painted and the legend is created by laser etching away the paint, allowing it to be illuminated by the LED backlight. Laser printing is the second most common method of printing legends.
This method uses heat and dye to permanently stain the keycap. The dye is seeped into and absorbed by the keycap material. This is unlike pad printing, where a layer of paint or ink is simply applied to the surface of the keycap. Dye-sublimation is more durable than pad printing and laser printing, as the dye is stained deep into the plastic and will not wear off, even with heavy use over prolonged periods of time. Produces a crystal clear, high contrast character perfect for keycap legends.
With this method it’s also very easy to create a large variety of different colored legends. Dye-sublimation does have drawbacks of its own; the dye must be darker than the keycap it’s being applied to. For example, no white lettering on a blue keycap. Dye-sublimation won’t even work with a black keycap, which is a large percentage of modern consumer keyboards. It’s also a more expensive technique than both pad and laser printing. For these reasons dye-sublimation is rarely used and generally only applied to high-end keycaps targeted to enthusiasts. Original IBM Model M boards used dye-sublimated keycaps and decades later they can still be found with crisp, easily readable legends.
Double-shot Injection Molding
Double shot keycaps are comprised of two separate plastic layers of differing colors, with the legend layer generally being ABS (but not always) because its properties make it easier to work with. This requires one mold of a specific color for the legend and a second of another color for the remainder of the keycap shell. The shell layer is molded around the legend layer creating a very high contrast character that is physically part of the keycap and can’t be worn off.
One minor downside with double shot keycaps is you’re limited to only two colors (legend color and key body color). This is the most complicated, time consuming, and costly method of applying legends because each color requires its own individual layer/mold. A very expensive procedure resulting in what many enthusiasts consider the best quality keycap possible.
Size, Format, and Stems
Obviously you’ll need whatever replacement keycaps you purchase to actually fit your keyboard. First, make sure you select the right shape for the stems of your switches. Most aftermarket keycaps are made to be compatible with the cross-shaped stems found on Cherry MX switches and the large selection of MX clones, such as Gateron. Keycaps for all other mechanical switch types are exceedingly rare. Good luck finding any meaningful selection of keycaps for Alps or Topre switches.
The second area to take into consideration is the layout of your keyboard, which will typically be either ANSI or ISO. There are minor differences with key size/position between the two standards (most apparent with the Enter key) and the ISO layout includes an extra key.
ISO layout with non-standard sized bottom row
The final aspect could prove to be the most frustrating. The bottom row. If you have a standard sized bottom row you’re in luck, as most keycap sets will fit as long as you have the same corresponding switch stem. However, some brands have keyboard models with oddly sized Ctrl, Win, and Alt keys. Often having those keys be of a non-standard size will mean the spacebar is also non-standard. A standard sized bottom row will have a 6.25x (also known as 6.25u, with the “u” meaning unit) spacebar with all other keys on the row being the same 1.25x size. For the sake of comparison, letter and number keys are considered 1x (1 unit) sized.
It’s a little difficult to explain, so if you’re having troubling picturing a standard bottom row layout take a quick look at this image provided by WASD Keyboards that might make it a little easier to understand.
Even if you can’t determine the size of your bottom row keys with 100% certainty (or just want a single set that works for both ANSI and ISO layouts) there is still hope thanks to universal keycap sets. For example, this universal translucent keycap set from Max Keyboard comes with multiple sizes of bottom row modifier keycaps and spacebars which they claim is fully compatible with 99% of mechanical keyboards on the market.