(Pieced together from conversations in noisy places while over caffeinated. . . and augmented as required)

“Slayer espresso machines are showing up now in real cafes all over the place.

Melbourne, San Francisco, Kirkland, Ann Arbor, and Calgary.  Soon more will be showing up in New York, Germany, Vancouver BC, New Zealand, Portland Oregon, and beyond.

For us this is the beginning of something very exciting.  Introducing an espresso machine specifically designed for the expert user, that enables variable pressure brewing for flavor profiling.  On the way, we have sampled hundreds of coffees.  What we have found is almost all coffee benefits from the lower pressure, pre-brew phase that Slayer pioneered.

Single Origin Espressos

Though not ALL coffee makes a great single origin espresso, it’s remarkable how much more you can coax from your coffee when brew pressure isn’t a full 9 bars right out of the gate.  Slayer also shows that it pays to WATCH what you’re brewing.  I realize that at this point in coffee history, the notion that it’s beneficial to watch your coffee as you are making it is almost a truism. Right this minute coffee aficionados worldwide are literally brewing with systems like vacuums, chemexes, or aero-presses that are constructed from clear materials conducive to visualization of the brewing within.

However, it is different for espresso machines.  Espresso, until recently at least, has been a dose, tamp, volume, time thing. Not really about watching as the coffee develops.  This seems misguided when taste, the ultimate arbiter of great espresso, can be controlled by watching and adjusting the shot as it’s brewing. . . based on what is seen.

This is where Slayer comes into the picture. A tool designed to enable the barista to watch their shot and control the pour as it’s happening.

Techniques and Considerations for Best Use

On the way here we’ve developed some techniques for using Slayer that we find give the best results.  What are these?  For one thing coffee can be dosed in smaller amounts.  Grind can be MUCH finer. And longer brew times are usually best.  By long brew times I don’t mean 23 seconds.  I mean 30, 40, 50 seconds, depending on coffee and flavor preferences.  Note: These longer times include the pre-brew phase plus brewing under higher pressure.

These factors are particular to each coffee. Experimentation is required to execute the perfect shot for each.  Earlier today I brewed an Ethiopian Wondo from Stumptown.  What I found was revealing.  Not only did I dose a smaller thirteen gram throw at a much finer grind etc, I realized the broadest, most complex flavor profile at a brew temperature of 207.4 degrees F.

I could not get the full benefit of the Wondo at lower temperatures of 203 and 201, which I also tried.  Palatable shots, yes.  Over-the-moon shots, no.

Higher Temperatures are Used Regularly for other brewing methods

Brew temperatures like this are often considered scorchers where espresso is concerned.  But with a lightly roasted single origin like the Wondo, they actually enable the coffee to blossom in a new way for espresso . . . when combined with lower pressure pre-brewing.

This makes sense on an intuitive level. If you brew French press coffee you know that the water temperature for extraction is much closer to boiling (212 F)  than it is to the roughly 200 degrees at which conventional espresso is typically brewed.  You also realize that in preparing French press, there is a violent eruption, as you pour the water over the coffee in the beaker and the coffee and water collide.

The Violent Explosion of Coffee & Water

In French press brewing the coffee violently shakes to life. It doubles and triples in volume even with a relatively small amount of water and expands & blooms upward releasing huge amounts of coffee aromatics into the air.  To compensate for this explosion, water is applied gradually to the coffee. Water is never poured over the grounds all at once.  You apply the water gradually to super-saturate the grounds, watching as the coffee expands and retreats, adding more water until you complete the pour.

The pre-brewing feature on Slayer is similar to this.

Higher temperature water at lower pressure is applied to the coffee in the portafilter, analogous to the French press brewing approach.  This allows the coffee to expand within the portafilter, under relatively gentle conditions. Only after this, after the coffee and water have reacted, is full pressure applied.

In contrast, when coffee is shot-gunned with a full nine bars of pressure it develops differently.

In fact, shot-gunning espresso results in an explosion of partially brewed coffee firing downward through the holes of the portafilter basket.  Channeling can be part of this violent eruption.  Under-extraction too. Pre-brewing on Slayer prevents channeling and enables the complete development of the coffee. When you do finish the shot with more pressure,  it is rare to encounter channeling, even with the lower dose of coffee.”

More anon.
Eric Perkunder in Seattle