Which keycap material: ABS or PBT?



If there is one question, I get more often than any other on the topic of mechanical keyboards keycaps, it would probably be: “which material is better: ABS or PBT?”


And, like anything else in this hobby, there’s no black or white answer to this question, of course. Preference will, as always, play a big role in this.


But, preference notwithstanding, there are some important factors to consider when choosing an ABS or PBT keycaps set, be it one that comes with your keyboard or an aftermarket one.


But first, let’s start by defining what are ABS and PBT plastics:


ABS or Acrylonitrile butadiene styrene is an opaque thermoplastic and amorphous

polymer. Thermoplastics become liquid at a certain temperature (105 degrees Celsius for ABS) and they can be heated to their melting point, cooled, and re-heated again without significant degradation. Instead of burning, thermoplastics like ABS liquefy under high temperatures.


ABS has a strong resistance to corrosive chemicals and physical impacts, it is very easy to machine and has a low melting temperature, making it perfect for injection molding manufacturing processes, but It is not typically used in high heat situations due to its low melting point.


ABS is also relatively inexpensive (currently around US $3.30 per kilogram) which, together with its other characteristics, makes ABS the preferred choice for a large number of applications across a wide range of industries.


PBT or Polybutylene terephthalate is also a thermoplastic engineering polymer. PBT is resistant to solvents, shrinks very little during forming, is mechanically strong and heat-resistant up to 150 °C. Besides high heat resistance, it is also chemical resistant and has good electrical properties. In general, PBT materials have more economical molding characteristics than many other thermoset polymers.


PBT is also inexpensive costing around US $3.20 per kilogram. It has many uses in electrical engineering and automotive construction among others, and it is known for being highly resistant to wear and discoloration.



Main factors to consider


Now let’s focus on these two materials when applied to keyboards’ keycaps. Here, there are basically five main factors to consider when choosing a set:


1) Sound profile - PBT usually sounds slightly bassier and lower pitched than an ABS set of similar size and thickness. As a result, a PBT set usually sounds less “plasticky” than an ABS one of the same thickness.


2) Wall thickness - The thicker the caps’ walls, the deeper and lower pitch the sound

ePBT Donutcat Royal Alpha (dye-sublimated PBT)

tends to be. A thick (1.5mm or more) ABS set will probably sound deeper than a thin PBT (1.3mm or less) set for example. So, if you prefer a keyboard with lower noise levels you should probably chose a keycap set with thicker walls (basic physics: thicker walls will better contain and damp the “clacky” noises of plastic attrition than thin ones). However, if you have two caps with the same walls thickness, one made out of ABS and one made out of PBT, then the PBT one will probably sound a few notches lower pitch than the ABS. Which usually makes thick PBT sets the better choice for keyboards focused on low noise.


3) Color options - Since ABS can be more easily colored, it offers a much wider color variety and saturation than PBT, which makes ABS the preferred material for keycaps sets that are more focused on aesthetics (i.e.: GMK and JTK sets designed and sold in group buy).


4) Durability - The biggest advantage of PBT in this application is its resistance to wear and UV discoloration when compared to ABS. PBT will hold its texture for far longer than ABS and, as a result, will take much longer to polish and to show the classic “shiny” look of heavily used keycaps. It will also hold its original color for far longer than ABS, which means white or clear colored PBT keycaps will not yellow out with time as it is fairly common with ABS sets.

Signature Plastics DCS Wyse Terminal (worn out double-shot ABS produced in 1988)

5) Legends printing process - The four most popular ways to print legends on keycaps of both materials are as follows:


a) Pad-printing: the process where legends are basically stamped on keycaps (ABS or PBT) surface with a silicone pad (pads dipped into ink transfer lettering onto the keycaps). By far the cheapest and most popular technique to print keycaps legends, and also the lowest quality. Pad printed legends will usually fade after a few months or years of heavy use.


b) Laser marking, etching, engraving, ablation, charring or coloring: multiple processes that use laser beams plus a variety of different methods to color the legends. Some of the most popular ways to use laser to print keycaps are:


i) the keycaps have their legends burned with the laser beam to charr a darker color legend into a lighter color material or to create bubbles (also known as “foam”) of lighter color legends into a darker color material;

Logitech G Pro (worn out laser-etched ABS)

ii) legends are “carved” into the plastic with the laser beam and then usually have the indented contours filled with ink; or


iii) thin transparent ABS keycaps are painted with a dark color and then have their legends etched by the laser beam, removing the surface ink layer from the legend’s contours and fillings, leaving layers of different colors or transparent plastic as the actual legend (usually in backlit keycaps to allow the L.E.D light underneath to shine through the legend).


c) Double-shot injection: the process where the caps and their legends are


injected with different molds and with plastics of different colors. As a result, these legends will never fade, since both the keycap and their legend materials are part of the keycap structure and will wear at the same pace all the way down. This process is known for providing high contrast (usually on ABS caps) as the legend is not affected by the color of the surface of the keycap. Double-shot is the gold standard for both opaque and backlit keycaps, but will obviously cost more to make than the other manufacturing techniques listed here.

JTK Bred (double-shot ABS)

While you can find PBT sets that have double-shot injection for their legends, the vast majority of PBT sets that use this manufacturing process usually have lower quality legends. While I don’t have any hard evidence to back this up, I’ve heard plenty of anecdotal reports that double-shot injection process with PBT can be very difficult to do acomplish with tight tolerances. As a result, most double-shot PBT sets tend to have fuzzier legends and many of them have the reviled stenciled fonts (specially on backlit caps). It seems there is some manufacturing limitation in isolating portions of different colored plastics with PBT (such as the areas inside letters A, B, D, Q, R, O and P).

GMK Triumph Adler (double-shot ABS)

d) Dye-sublimation: the process where legends are thermally (heat) printed with dark characters on top of light-colored caps. This process is mostly used with PBT

ePBT Donutcat Royal Alpha (reverse dye-sublimated)

keycaps, since PBT can better absorb the dye on this technique. Lately, ePBT and Infinikey, among others, have been releasing more sets with “reversed dye sublimation”, where light color keys are dyed with darker and more vibrant colors around the legends instead (where the legends are left unpainted with the lighter background color).




So, with all these factors in mind, here goes some of my considerations and recommendations to newcomers to the mechanical keyboard hobby:



On the PBT side


For my particular use cases, I usually prefer PBT sets in the Cherry or OEM profiles for

Drop Artifact Bloom BLACK ON WHITE (dye-sublimated PBT)

my “workhorse” keyboards (the ones I use to type during my 8 to 10 hours workdays) simply because they hold up better on the durability side, especially because of their better resistance to scratches and wear (polished shiny look), for their lower pitch sound and for their slightly textured surface (in most cases, but not all, since it is possible to make smooth and slick PBT caps as well) that usually feel less slippery when typing with sweaty hands.

Topre Realforce R2 (dye-sublimated PBT)

I also prefer PBT for gaming boards, since the WASD keys take a lot longer to shine than ABS counterparts and thus keep the keyboard looking more uniform throughout its lifespan.


For the types of PBT sets I usually go for, my favorite sets are from EnjoyPBT (or ePBT as they are also known as), which have thick 1.5mm walls and perfectly dye-sublimated legends (sharpness and alignment). High quality PBT sets usually have dye-sublimated legends.


On the budget end, Drop's Artifact Bloom series (BLACK ON WHITE, FUTURES, DUSK, VINTAGE, MATCHA MANGO and RED VELVET) are very good thick dye-sublimated PBT sets for $45, and Tai-hao, YMDK and NPKC* are known suppliers of thin PBT sets with decent double-shot legends.



On the ABS side


For my “aesthetic” keyboards I do use ABS sets, but mostly thick-walled ones (such as

ePBT Dolch (double-shot ABS)

those from GMK, JTK, ePBT --who also makes ABS sets despite their name—for Cherry profile, and Signature Plastics, MaxKey and Domikey for SA profile). Since I do not type for extended periods of time on these boards (and because I usually rotate between them) durability and the “wear-and-tear looks” are less of a concern. Besides, thick ABS sets can sound really nice when you go for louder and “clacky” builds, which I do like to use in my home office every once in a while.



GMK Kaiju (double-shot ABS)

When considering the budget for ABS keycaps, prices can vary a lot depending on the thickness and quality of the legends. We all know how expensive and hard to get GMK, JTK and SP sets can be on the ABS side of things (prices usually starting at around US $120 and waiting times of up to a year or more). So, it goes without saying that these types of caps should not be the first choice for people on a budget or on a hurry.


But the ABS sets made by ePBT (I know… Always confusing because of their name) are very high quality and can usually be found for between US $70 and $90 on places such as 1UP Keyboards and KBDfans. These sets are thick (1.5mm) and have around 80% of the quality of a GMK set (although with less vibrant colors) and with decent compatibility for more exotic layouts such as 65% and 75% keyboards.



On the high-profile side (ABS and PBT)


Domikey SA Atlantis (double-shot ABS)

On the SA profile side of things, I like Domikey ABS sets for having the same thickness then the much more expensive ones made by Signature Plastics, while offering amazing compatibility for pretty much any layout you can possibly think of (maybe with the exception of ortholinear layouts). While they don’t offer a large variety of colors, you can find complete Domikey sets for between US $95 and $110 on places like Drop (DOLCH, SEMICONDUCTOR and WESTERN sets) and Banggood (DOLCH, 1980s, CRISIS and GAS SHELL).


Signature Plastics also make SA caps in dye-sublimated PBT (ICE CAP, SNOW CAP and INDUSTRIAL), which have amazing quality but are very expensive (north of US $150 for a full set). So, for that reason, I recently have tried a couple of new PBT high-profile formats out there.


The first one is from Drop and their exclusive MT3 profile, which is almost as tall as SA,

Drop /DEV/TTY MT3 Triumph (dye-sublimated PBT)

but with a wider and “deeper-dished” sculpted shape that is very pleasant to type on, and that comes in both dye-sublimated PBT (/DEV/TTY) and double-shot ABS (SUSUWATARI, DASHER, JUKEBOX, CAMILLO, WHITE-ON-BLACK and BLACK-ON-WHITE). Drop has a good variety of colors and designs in their MT3 line-up and they offer very good compatibility for most layouts, while costing less than Signature Plastics’ SA sets. I highly recommended MT3 for people who enjoy high profile keycaps!



KAT DP0385 (dye-sublimated PBT)

The second is from Keyreative in their KAT profile (they also have the KAM profile, where all rows have the same height and shape), which is somewhere in between SA and Cherry in height, while offering a nice sculpted profile that is not too jarring. These are made of dye-sublimated PBT with very high-quality legends and can be found on TheKey.Company, KBDfans, zFrontier and Kono stores among others.



On the backlit side


Here is where ABS sets mostly dominate, since it seems to be much easier to manipulate when manufacturing keycaps with transparent legends that are sharp and perfectly transparent (no color tinting) to allow very bright back-lighting. There are two ways of producing these sets: double-shot injection (higher quality) and laser etching (lower quality) as explained before.


But thin laser-etched ABS is usually at the bottom of the durability scale and will get oily

Vortex KBTalking Pure (worn out laser etched ABS produced in 2012)

and shiny after a few days of use, and eventually even chipped and peeled after a few months and years. They’re also loud, given their thin walls. And because keyboard manufacturers always try to save as much as possible in their included keycaps, these are without exception (that I know of) very thin (usually around 1mm or less), which means they can easily break as well. The vast majority of RGB backlit keyboards, usually gaming oriented ones, come with thin laser-etched ABS backlit keycaps to complement their extensive light shows and to save on cost.


So, unsurprisingly, for my production keyboards that come with these types of keycaps, I immediately replace them with higher quality aftermarket sets whenever possible.


Matrix Keyboards Caribbean (backlit double-shot PBT)

On the aftermarket though, is where you can find higher quality backlit keycaps. I have seen a few suppliers that have decent quality double-shot backlit PBT sets, such as Tai-Hao, Ducky, Vortex and Matrix Keyboards, such as the one I used in my silent GMMK build, and more recently the ones offered by Drop (their Skylight Series), Razer and Corsair. These are also very competitively priced, varying between $30 for the cheapest to $45 for the most expensive ones.


While their transparent legends tend to be slightly tinted with the surrounding plastic color, and may have some darker spots in the transparent areas of some letters, these

Razer Green (backlit double-shot PBT)

at least have nicer and sharper non-stenciled fonts. But these are all OEM profile (taller than Cherry) and usually don’t have good compatibility for exotic layouts, focusing instead on traditional 60%, TKL and full-size boards (with the exception of Drop’s Skylight series that at least offer 1.75U shift keys for 65% boards).



Conclusion


Clearly, there is no right or wrong answer for the ABS vs. PBT discussion. It all depends on your use case, budget and preference. As someone who uses both materials regularly, I can appreciate the advantages of both materials.


While I do intend to produce videos on the topic of keycaps, where I'll cover different suppliers, materials, profiles and mounting options, I hope this written article can help and guide you in your keycaps buying decisions in the meantime.



* Disclaimer: some of the products linked in this article are affiliated links and will result in a small commission (paid by the retailer in question) to this website's owner.

300x50.jpg