Keycaps

Page Contents:

  1. Introduction
  2. Materials
  3. Legend Printing Methods
  4. Thickness
  5. Layout Compatibility
  6. Profiles
  7. Manufacturers

Introduction

20140713-P1010647Once you purchase a mechanical keyboard, sooner or later you’re going to want some replacement keycaps. Collecting and swapping keycaps is a great part of owning a mechanical keyboard — you like customizing your equipment, right? 🙂

Finding replacement keycaps is, by far, easiest for Cherry MX keyboards. While you can find replacement keycaps for Topre, ALPS, buckling spring, and other keyboards, the selection is much more limited. Unicomp is the only company that currently sells new buckling spring keycaps, and no company current sells new ALPS keycaps (although Matias has plans to release some later in 2014). Realforce used to produce replacement Topre keycap sets, but has discontinued all of them. Moreover, non-Cherry MX keyboards frequently have nonstandard layouts, so even if you can find replacement keycaps, there’s no guarantee you’ll have a properly sized replacement for every key on your keyboard.

In contrast, aftermarket Cherry MX keycaps are a booming business. A wide variety of replacement Cherry MX keycap sets are available for sale, in a variety of plastics, color schemes (“colorways”), and layouts.

Here’s what you need to know about keycaps:

Materials

Keycaps are usually made from ABS or PBT plastic. Both of these plastics have pros and cons, which I outline below. Less commonly, keycaps are made from POM, polycarbonate or other plastics/resins, or even metals like zinc, aluminum, or titanium.

  • ABS (Acrylonitrile butadiene styrene)

ABS is the most common plastic used in keycap manufacturing, and also one of the most common plastics used for consumer goods in general, including LEGOs, storage bins, etc. As a keycap material, ABS is cheap, strong, and easy to manufacture, so replacement ABS keycap sets are usually the most affordable option available.

Legends on ABS keys can be pad printed, laser etched/engraved, doubleshot, or UV printed, which have varying degrees of wear resistance (more on this below). ABS keycaps come in a variety of thicknesses, and most keyboard enthusiasts agree that thicker keycaps are more desirable due to their heftier feel, deeper sound, and overall quality.

Criticism of ABS keycaps usually focuses on their susceptibility to “shine.” Constant touching in combination with caustic skin oils can cause ABS keycaps to lose their texture in as quickly as a few months. Many keyboardists dislike the resulting “shininess” and smoothness, often saying that shiny ABS keycaps feel greasy. Additionally, some of the most common legend printing methods used with ABS caps, such as laser etching and pad printing, are susceptible to wearing off along with the surface texture.

Stock keycaps that come with new mechanical keyboards are almost always ABS unless specifically advertised otherwise.

  • PBT (Polybutylene terephthalate)

PBT is the second most common keycap material, behind ABS. PBT is more expensive and difficult to manufacture than ABS, which is why it’s not more commonly used. However, PBT has a big advantage compared to ABS: it is much more resistant to shine. Some keyboard enthusiasts mistakenly say that PBT is completely impervious to shine. This is not true — PBT can also be shined up by heavy use and caustic hand oils, but it takes much longer to do so. Furthermore, many keyboardists find that PBT has an overall better feel, producing a deeper, more appealing typing sound than ABS keycaps.

Like ABS, PBT keycaps come in a variety of thicknesses. However, since PBT is a premium material, manufacturers usually ‘go all the way’ and make it thick to boot. Thin PBT caps exist, but are not very common on the aftermarket.

Legends are almost always printed on PBT keycaps using dye sublimation, a process in which dyes are deeply embedded in the plastic. Dye sublimated legends are virtually impossible to wear off, unlike many of the printing processes used with ABS keycaps. (The main reason the dye sublimation process can’t be used with ABS is because the sublimation process requires a crystalline substrate, like PBT, that dyes can penetrate. ABS is an amorphous material and by nature cannot readily accept dyes.)

So, while PBT keycaps have a higher price tag than ABS keycaps, they have some significant advantages. However, there are a couple notable problems. First, PBT is notoriously difficult to mold for larger keys, so PBT keycap sets usually come with ABS spacebars. Color matching is usually not a problem, but many keyboardists do not like having a spacebar made of a different, shine-susceptible material. Second, dye-sublimation has an important limitation: the legend must be darker than the keycap material. It is not possible to dye a light legend onto a dark plastic. Therefore, there are limitations with regard to the colorways possible on PBT keycaps.

Legend Printing Methods

  • Pad Printing: This is the cheapest possible way to print legends, and involves simply applying ink onto the surface of the keycap. Most mass-produced rubber dome and scissor switch keyboards have pad printed legends. Pad printed legends can easily wear off during normal usage, and you can often feel their outline with your fingertips when typing. For these reasons, pad printing is almost universally disliked. On some high-end keycap sets with additional international legends (e.g., Cyrillic), the secondary legends are pad printed and covered with a clear coat for added durability. In particular, GMK is known to use this method when they pad print keys. Most anecdotal information suggests that the clear coating is highly durable and can protect the underlying pad printing for many years. Unfortunately, this coating is not usually present on cheap pad printed keys.
  • Doubleshot Injection Molding: Doubleshot molding means that the legends are not printed at all, but rather integrated into the keycap. Through the use of precision molds, the keycap manufacturer first produces the key with a hollow area where the legend should be. A second injection of liquid plastic fills the gap, and forms an integral legend. Unlike dye sublimation, doubleshot molding can be used to create any color combination. Unlike pad printing, the legend can never be worn off, because it is part of the key itself. This technique has historically been used only with ABS keycaps. A few doubleshot PBT sets have recently been produced by Vortex, but no other manufacturers have used the technique with PBT.
  • Laser Etching: This process involves using a laser to alter the surface color of a keycap: either producing white lettering on black keycaps, or black lettering on white keycaps. No examples exist of colored laser-etched legends. In general, laser etched legends are much duller than doubleshot, dye sublimated, or pad printed legends. The feel and durability of laser etched legends varies. Sometimes laser etching alters the keycap texture; other times it does not. Sometimes it is worn off as easily as pad printing; sometimes it outlasts pad printing. The details depend on the technology, keycap material and quality, and so on. Matias is one company known for using laser etching.
  • Laser Engraving: Like laser etching, laser engraving involves creating legends with a laser. However, the goal of laser engraving is not to simply mark the keycap surface, but rather to burn deep grooves. These grooves are usually infilled with high-contrast ink. Keycaps with white infilled legends are often susceptible to staining and greying. Laser engraving was commonly used on Cherry’s black POM keycaps in the 1990s, but is not common in contemporary keycap manufacturing.
  • Dye Sublimation: Dye sublimation involves permanently staining plastic keycaps with a dye. The process requires a very high temperature, above the melting point of ABS, so the technique can only be used with PBT keycaps. Dye sublimated legends are virtually impossible to wear off; however, the process’s main limitation is that the dye must be darker than the plastic. Dye sublimation cannot be used to dye a light color onto a dark plastic, limiting the colorways available for dye sublimated PBT keycaps. Unlike lasering and pad printing, dye sublimation does not alter key texture.
  • UV Printing: UV printing is a new keycap printing technology wherein legends are printed at a very high DPI, lacquered with a protective coating, and cured with UV light. This process has recently been adopted by QWERKeys for novelty keys, Matias for a line of upcoming PBT replacement keys, and WASD Keyboards for its custom keycap creation service. According to WASD Keyboards, while the process results in less brilliant whites, other colors come out very well and the protective coating is actually harder than ABS or PBT. Thus, WASD claims that its UV-printed keys are especially resistant to shine and legend fading. Since UV printing is a new process, not much data are available to corroborate these claims. I will update this section and post news articles as more information on UV printing becomes available.

Thickness

As I noted earlier, keycaps come in a variety of thicknesses. In general, thicker keycaps produce a deeper typing sound and a more substantial key feel. Many keyboardists prefer using thick keycaps for these reasons, but as with all things relating to mechanical keyboards, it is ultimately a matter of personal taste. If you prefer a higher pitched “clack” rather than a lower pitched “thunk,” you may prefer using thinner keycaps such as Signature Plastics’ DCS profile.

Layout Compatibility

As I discussed in Form Factors & Layouts, when buying aftermarket keycaps you must take care to ensure that your entire keyboard is covered. You do not want to purchase a set of replacement caps only to determine your right shift is the wrong size, or that you’re missing Windows keys. Here’s what you need to know.

  • When Buying Keycaps, It’s All About the Standard “Filco” or “OEM” Layout

Most mechanical keyboards in production today have a standard layout, also known as a “Filco” or “OEM” layout. Perhaps unsurprisingly, then, most aftermarket keycap sets are designed to cover a standard layout.

filco-standard-layout

Most but not all CM Storm, Filco, Ducky, WASD, Das, and other major brand name keyboards have a standard layout. The most common 60% board, the Poker II, also has a standard layout. On that note, remember what I told you before: tenkeyless and 60% boards can indeed have standard layouts, despite not having full-size form factors.

If you’re unsure what layout your keyboard has, how do you figure it out? Well, you can always ask for help at a place like /r/mechanicalkeyboards, but you can also just use your eyes! Look at your keyboard and decide whether it has the same layout as the image above. If all the keys are the same size and shape, you’re good to go! If something looks off, such as unusually-sized modifier keys to the left and right of your spacebar, then you don’t have a standard layout — for the keys that it has 🙂 This is one of the reasons that the Poker II is more popular than other 60% boards like the Pure — unlike with the Pure, you won’t have any problems finding replacement keycaps for a Poker II.

Let’s try one together. Take a look at the below photo (click to enlarge):

non-standard-layout

Notice how the modifier keys to the left and right of the spacebar are not all the same width. This is a non-standard layout. Most aftermarket keycap sets will not fully cover this keyboard.

The bottom row modifiers are probably the most common place where layouts deviate from a standard layout, but it’s not the only place. Use your eyes to critically assess your keyboard versus the standard Filco pictured above, and ask for help if you need it.

  • If you don’t have a standard layout, it will be harder, but not impossible to find a full replacement set.

So, most aftermarket keycap sets are designed for a standard layout but you have a non-standard keyboard. Are you screwed? Not completely. Even if you’ve got a non-standard keyboard, most of the keys from a replacement keycap set will fit your keyboard, including all of the alphanumerics and usually all other 1x keys like arrow keys and function keys. As I noted, the modifiers are usually the problem.

To deal with this problem, you have two options. First, check to see if there is an “extension” kit sold alongside your keycap set. Sometimes, keycap manufacturers sell extension sets with alternative modifier sizes to help customers with non-standard layouts. Failing this, your only other practical option is to purchase a separate set of modifiers keys and combine them with your replacement keycap set. Yes, this means that you won’t have a fully matching color scheme, but fortunately you can find modifiers in a variety of colors, making it relatively easy to create a pleasing match. Red, green, and blue (RGB) modifiers are one commonly available kit. Check the Buyer’s Guide for information on where to purchase such kits.

Profiles

Keep in mind that not all keycaps are the same shape. Manufacturers sculpt their keycaps differently — height, surface angle, etc. Moreover, keycaps within a single set aren’t always interchangeable — each row of keys usually has a different sculpted shape. This means you can’t rearrange caps outside of their respective rows, or you will end up with mismatched profiles. (There are some exceptions, such as Signature Plastics’ DSA profile, which has flat tops and is completely row-independent.) You also need to keep keycap profile in mind when combining keysets — such as when buying colored modifiers. If you purchase keys with a different profile, they will not match your existing keys in terms of height and angle.

Note that the term “profile” can be used to describe the entirety of a keyset (e.g., Cherry profile or DCS profile), or alternately, to describe a single row within a certain profile (e.g., DCS row 2).

Observe Topre profile:

20140723_165427

Now, observe Cherry profile:

20140723_171342

Notice that each row of keys has a slightly different height and angle, in both Topre and Cherry profiles. Moreover, notice that Topre and Cherry profiles are wholly different from one another.

There are many profiles in existence:

  • OEM Profile: What you’ll almost always find on stock keycaps from companies like WASD, Filco, Ducky, CM Storm, KUL, and more. Just your average Joe profile, similar to keyboards you’ve typed on all your life. Found on MX keyboards, ALPS keyboards, and other keyboards.
  • Signature Plastics’ DCS Profile: SP’s standard profile. Very similar to OEM profile. Only made by Signature Plastics. Most commonly made with an MX stem.
  • Signature Plastics’ DSA Profile: A short, square, flat-top profile that is the same across all rows. DSA is popular among keyboardists who use Dvorak, Colemak, or other nonstandard key layouts. (OEM/DCS/etc. profile caps cannot be rearranged into the necessary configurations without causing crazy profile problems.) Only made by Signature Plastics. Most commonly made with an MX stem.
  • Signature Plastics’ SA Profile: A tall, square profile with spherical tops. Not the same across all rows, and not a very common profile. SA profile keys are much thicker than DCS or SA profile caps. Only made by Signature Plastics. Most commonly made with an MX stem.
  • Cherry Profile: Found on vintage Cherry keyboards as well as Cherry reproduction sets from GMK and BSP. Similar to OEM, but lower profile and often with a scooped F and J. MX keyboards only.
  • Topre Profile: Similar to OEM profile, but found on Topre keyboards only.

The table, below, shows how different manufacturers label keycap rows.

profiles1

Manufacturers

Here are the major keycap manufacturers. This list is MX-centric; as mentioned earlier, non-MX replacement caps are a small market. For more information on where to buy these products, check the Buyer’s Guide.

  • Signature Plastics: SP is one of the biggest manufacturers of aftermarket MX keycaps. They sell directly through http://www.pimpmykeyboard.com/. You can either buy caps from their inventory (usually with very basic colors) using the “Key Shop” link, or you can participate in a Group Buy. In a Group Buy, someone (usually an enthusiast) submits a keyset design to SP, which opens up a limited-time sale. The more people purchase the set, the better the price gets. And when the GB is over, the set is sold out — usually none are put into SP’s inventory. GBs are a cool way to get a good deal on a limited edition product. The designs are usually more interesting than what’s available in the Key Shop. All SP keycaps are thin doubleshot ABS unless otherwise noted.
  • GMK: GMK is a German company that now owns all of Cherry Corp’s original keycap manufacturing equipment. All GMK keycaps are thick doubleshot ABS, in Cherry profile with MX stems. GMK keycaps are a top quality product. GMK only sells via community-organized Group Buys, a few of which occur each year.
  • Ducky: Ducky’s main business is keyboards, but they also sell their keycaps separately. Most Ducky sets are PBT, either lasered or dyesubbed. Their winkeys have a duck instead of a Windows logo, but if you can live with that, they produce some nice colorways that won’t break the bank. All aftermarket Ducky keycaps are for MX keyboards.
  • Vortex: Vortex, the manufacturer of the popular Poker II 60% keyboard, manufactures and sells some keycaps. As of late, they have been focusing on producing doubleshot PBT keycaps, a notoriously difficult manufacturing process. No other keycap manufacturer has produced a doubleshot PBT set to date. All Vortex keycaps have MX stems.
  • Unicomp: Unicomp, the last remaining manufacturer of buckling spring keyboards, also sells a limited selection of replacement buckling spring keycaps. All Unicomp keycaps are dyesubbed PBT.
  • Tai Hao: Tai Hao is a Taiwanese company that produces inexpensive doubleshot ABS keys. They sell stock keycaps to other OEMs, and also take Group Buy orders from the community, but they do not sell directly. Tai Hao has the capability to produce both MX and ALPS stems.
  • Topre: Topre no longer offers colored aftermarket Topre keysets. However, they do still sell replacement stock Happy Hacking Keyboard keycaps, which are available from EliteKeyboards.com in the United States. It remains to be seen whether any other keycaps manufacturers will clone the Topre stem to address demand for replacement Topre caps.

The above list is not comprehensive, but it covers the major manufacturers and is a great starting point for making an informed keycap purchase. For more information on where to buy these and other keycaps, be sure to check out the Buyer’s Guide.

Next: Personal Preference