Keycaps, they’re probably the most recognisable customisation component of a mechanical keyboard. And the plastic that make up these keycaps can alter the feeling and sound when used.
Some keycaps use dense plastics that feel “dry” or sandy to the touch while also giving a more solid sound when pressed. Others can be “wet” but offer durability in other ways.
Plastics have varying strengths and weaknesses so it’s hard to just say one is better than the other. What’s right for me may not be right for you. Hence why it’s worth having a rough idea before making a purchase.
Keycaps are created out of many different materials. From silicone, to wood, to metal, you name it there’s probably a design for it somewhere.
For the most part plastic is the most commonly used keycap material. And of that, three types of plastic are the most prominent.
From most common to least common, they are; ABS, PBT, and POM.
Here’s a handy comparison table of each of the plastics:
|Texture||Smooth||Rough - Sandy||Smooth|
|Yellows with UV Exposure||Yes||No||No|
|Shines over time||Yes||No||No|
|Rate of wear||Fast||Slow||Slow|
|Melting Point (°C)||105°||225°||166°|
ABS – Acrulonitrile Butadiene Styrene
The most commonly used plastic in today’s world of mechanical keyboards. ABS is cheap and semi-durable.
It’s also easy to mould thanks to its low melting point. Meaning ABS is better at producing more consistent keysets and is the better choice for double-shot keycaps.
ABS by nature is smooth, think Lego smooth, as it’s the plastic Lego is made of. This gives ABS essentially a slick, wet feeling to the touch.
It is possible to get textured ABS, though, over time this texture will wear. In fact, ABS wears the quickest of the three plastics.
That’s not the only downside to ABS, over time the keycaps will shine with wear as well as yellow when continually exposed to UV light.
Cheaper ABS keysets can feel somewhat mushy when compared to PBT but it’ll be hard to notice without doing a side by side comparison.
Keysets featuring ABS
PBT – Polybutylene Terephthalate
The more expensive option, PBT continues to gain traction in the mechanical keyboard community as of late. PBT feels solid in comparison to ABS.
To the touch PBT feels grainy or dry, quite different to smooth ABS keycaps. However, it is entirely possible to find PBT sets that are smooth, eg. Signature Plastics’ Ice Caps.
PBT wears slower than ABS, and as the texture is a component of PBT it doesn’t go away.
Comparing PBT to ABS highlights the slower rate of wear. And, unlike ABS, there’s no yellowing problem nor does PBT shine with use.
It’s not without its drawbacks, though. Mentioned above, PBT plastic can be expensive.
Moulding PBT is not an easy process either. PBT has to reach higher temperatures in order to melt, and this much energy output is quite expensive.
Respectively, PBT has to cool down from a higher temperature and this process can cause warping or shrinking. Warped keys can be fixed by applying small heat while under uniform pressure, thanks to the increased durability.
This is why PBT double-shot keys are quite hard to find. It’s expensive but more importantly harder to produce thanks to shrinkage during the moulding process.
However, the durability and higher melting point makes PBT an excellent choice for dye-sublimation, which bonds the ink to the plastic. It also makes DIY dying quite easy.
Keysets featuring PBT
POM – Polyoxymethelene
Also known as Delrin, POM is not commonly found as whole keycaps, though they do exist. Hard and durable, while also much less dense compared to PBT or ABS keycaps.
To the touch POM is like ABS with its smooth surface that feels “wet” to the touch. Think of POM like a hybrid that’s smooth like ABS but also durable like PBT.
There aren’t that many manufacturers using POM. Vortex use POM for their lettering infill in their double-shot PBT keycaps.
Laser-etching or laser-etched infill is used to legends on POM keycaps.
Keyboards with POM keyaps
As with any kind of personal preference articles, there’s always a caveat or two. This time it’s keycap manufacturers.
For the most part the information mentioned above is fairly consistent. However, I do need to note that there is a scale when it comes to buying keysets.
Some aftermarket ketset manufacturers produce keycaps of ABS that is greater in quality than most PBT keysets. GMK and Signature Plastics are some that come to mind. These are manufacturers who have excellent production conditions as well as some of, if it not, the best moulds. Keycaps from these manufacturers are also of significant thickness.
GMK’s double-shot keysets are considered to be the best available. Their colour schemes are highly desired, while the ABS they produce does have a slight texture to them. It is inevitable that over time the ABS will wear and eventually shine but this process happens slower than most ABS keyset manufacturers. Similar with Signature Plastics.
It’s also entirely possible to get cheap PBT keysets. These are cheap to produce to offer a more premium sense of value over competitors. But do not be fooled. A lot of the time these keysets are also relatively thin. This type of PBT keycap is generally better than keyboards with stock ABS keycaps. However, they’re not much better than aftermarket producers.
Just some food for thought when it comes to purchasing a keyboard with ABS or PBT keycaps. Especially when PBT sets are cheaper than GMK’s ABS sets.
Me, personally I prefer PBT sets over ABS keysets. I use EnjoyPBT as my daily driver over my GMK sets due to the feeling and the rate of wear.
Production process for different plastics
Due to each plastic having their differing compositions and attributes means different processes are used to make keysets. While some processes of adding legends can be used for the three different types of plastics, other processes are much harder to reproduce.
Let’s talk about adding legends onto keysets. (Legends are the letters or numbers on each keycap. They indicate each keys’ function.)
Through various creative means, printing is one of the cheaper ways of adding legends to keycaps. A printer is used to print legends on to keycaps.
This process is notorious for the rate they wear and disappear over time. It’s quick, with some sets deteriorating significantly quicker than others.
Commonly found on the majority of keyboards world wide.
A few different laser marking methods exist; engraving/ablation, charring, and foaming. These processes are rather similar in execution with the primary differences being the amount of heat applied as well as the finish.
Charring heats the plastic to produce a dark shade of the original plastic’s colour. Foaming simply leaves tiny, solidified bubbles that are brighter than the keycap.
Engraving, or ablation as it also goes by, burns grooves into the plastic. These grooves can work in a few different ways, they can be left as is or filled with a colour. The more creative option is to use transparent plastic for the keycap base, paint over the top and then engrave the top layer, mimicking the double-shot process.
Much more expensive and more complex than any other processes on this list is double-shot injection moulding (double-shot for short). Produced by forming one part of the keycap with a mould first, then another colour of plastic is added to make up the rest of the keycap. This means 2 colours can be used to form one piece of plastic.
Considered the best type of keycap production method as the legend and the surrounding keycap are both individual pieces that make one whole piece. Moulds have to be produced as well as the cost of using two sets of plastic to create the keycaps, means this is an expensive way to create keycaps.
Wear on each keycap is uniform as the legend is comprised of two pieces of plastic. This means the legends won’t rub off over time (well if you don’t wear the plastic down to the stems).
Predominantly ABS is used but we’re starting to see more double-shot PBT sets being made.
Dye-subbed for short, is another printing process but with different limitations due to its complexity.
Printed legends, designs, and even colours are added to keycaps by heating both the keycap and the ink. The ink’s temperature needs to be raised high enough that it turns into a vapour. This process allows the pores of the plastic to open and for the ink vapour to enter them.
As the vapour is added to the base keycap colour, whites inks cannot be printed as nothing is brighter than white, while black keycaps cannot be printed on top of, as nothing is darker than black.
On very rare occasions you will find dye-subbed ABS keycap but nearly all the time PBT will be used. This is due to the higher melting point of PBT.
I hope this helps shed some light on keycap plastics, and the processes used to make them. I understand that it’s not always possible to buy the best but if you do your research you’ll find arguments for why one is better than the other.
The most important consideration is what your personal preference is. If you’re a person who likes the slippery feeling of ABS keycaps, then you probably won’t enjoy PBT. Inversely, if you prefer grip and texture on your keycaps then PBT is the way to go.
Just remember that thickness and build quality really do determine a good keyset, hence why GMK gets ample praise despite being ABS.