So today we're going to talk about the two new group head parts that go into here.
Now, the first thing you might notice is that this is a very different color.
This is obviously not brass.
This is a material called PPS.
And PPS is a material that the espresso machine industry has been using to replace brass.
In fact, our valve supplier company called Olab that also supplies to La Marzocco and many others
has been moving off brass onto this exact PPS material,
because it can handle high temperatures, it's very easy to clean,
and it doesn't have any toxicity issues.
It is FDA approved and now it's a very safe bet.
I mean we're looking at 10 years of Olab transitioning to this.
And one of the reasons that we switched off brass is because of this issue with zinc leaching out.
Now, depending on what your water chemistry is,
brass is a mix of various other metals
and zinc can leach out,
which makes it look very tarnished and ugly.
It can also make the surface a bit pitted.
There's also a problem where the screws that hold this part in place are made of stainless steel,
because that's what lasts,
and that there's an interaction between the stainless steel and the brass,
which makes those screws extremely hard to remove if you don't take them out soon.
And some of you have noticed that.
To make things worse, our screws in here have had a Phillips head on them
and some of you, in trying to get those screws out, have slightly damaged the head.
That's okay.
But what isn't okay is that that makes a little bit of stainless steel powder,
which is now free stainless steel, which will then go and add to more interaction with the brass.
So all in all, brass is not the best thing.
There's one final issue, which is the global standards -
specifically Germany and Japan -
for allowed lead content in brass.
These have been going steadily more and more strict,
to the point now where naturally occurring levels of lead
can occasionally make a batch be declared unfit for human use.
This means that every time you make anything out of brass, you have to test and retest.
Our quantities are quite small,
but the larger companies have been moving off brass for that reason,
because it's obviously very unfortunate if you have to melt down a whole run
because of very small amounts of lead.
Back in 1970, no one really worried about lead,
but it's an issue.
And I'd also say that one of the issues with lead and brass is that when you try to use CNC,
which is computer-controlled drilling of these parts,
that when you have a lead-free part, it's very hard.
It's much more difficult to tool to round it,
and that means your CNC costs are much higher.
Of course, you need it to be lead free because you don't want to contaminate the water,
but that's part of the high cost.
We have been making CNC'd brass versions of these parts for the past seven years,
they've been a quite expensive part,
and they've required fairly frequent cleaning
because of that zinc leaching issue and the tarnishing.
It also turns out - we don't know exactly why -
but coffee oils tend to stick quite a lot to brass.
This PPS material is a dream.
We about a year and a half ago started making variations of this part in a number of other materials.
PEEK was one of them,
ULTEM another one,
and this PPS material.
Now, ULTEM is what we've used as the part inside the water mixing - the manifold -
inside the machine,
but what we found with this is that it was subjected to such heat stress
that the ULTEM would crack here
and so we couldn't use it.
Now, PEEK is one of the most expensive materials you can buy.
It's used for in-body transplant materials, it's incredibly safe,
it's incredibly expensive.
We didn't mind, because the parts are small.
However, under that heat stress, these parts warped.
So we couldn't use PEEK either.
When we switched to PPS, we were delighted to find a couple of things:
One is it didn't warp, it didn't crack,
and in our testing of everything for cleaning,
only ULTEM was better at resisting coffee oil sticking to it.
It was a close second to that.
But there was another big reason to redo these parts,
and that's that when Ben Champion came on board as the principal mechanical engineer for Decent Espresso,
he had been cooperating with me on Home Barista - this is how he got the job -
he was doing fluid simulations of water flow over these parts.
Because these parts, if you were to look at them in traditional Italian machines,
you will often see just one hole for water or five holes.
When he did the simulations,
he found that those were really terrible at providing even water flow during pre-infusion.
Now, once water builds up pressure
then those five holes just form a barrier above the puck and it's quite even.
But during the pre-infusion stage,
the water was really drilling into different spots,
and we thought that this was partially the reason why we saw so much channeling on traditional machines
and also why light roast didn't taste good
and why slower pre-infusions didn't work well.
So Ben made this assumption that what we wanted was a part that really evenly distributed water.
And that's what we've been doing for seven years.
And he was mostly right.
I say mostly right, because that did give us way better coffee.
I mean it was much, much better than the five-hole approach,
BUT
but this is where Stefan Riebes - a coffee researcher in Belgium -
he had a really innovative idea;
he did something called a Radial Extraction Test.
And what he did is he separated the coffee coming out in various concentric circles.
So he tested the espresso in the center, in the middle and the outside ring,
and he found something pretty much devastating.
Because when you analyze that
you might find that your coffee is extracted at, let's say, 21%.
That means 21% of the coffee in the puck end up in the drink.
However, it turns out the center was something like 24% extraction
and the outside was something like 14% extraction.
So we're getting really just awful espresso on the outside
and I would say over-concentrated stuff on the inside.
It was Stefan Riebes, Ben and Luca Constanzo who formed the core group of coffee experts
to think about how to address what Stefan Riebes had figured out.
And they tried all sorts of different patterns,
and I'm not kidding when it actually took two years.
Because these guys are all serious coffee people,
and they would switch things around and then
take lots and lots of notes of all these different coffees,
and which was better under what circumstance, which was worse.
This design is the one that they settled on for one key reason.
And that's that in no situation, no shot, was it worse than the previous one
and in some cases, it was better.
Every other design was worse in some cases.
And definitely, we wouldn't want to make anything worse.
But what we found is pretty striking:
This outside extraction has jumped from about 14% to 16%
with the new distribution of holes.
And that has overall bumped up the total extraction of your coffee
from around 0.5% to 1%, which is just for free.
Now, the way it does that, I'm not going to entirely talk about because that's our little secret sauce,
but let's just say that that is going to give you shots that have less acidity, more balance,
it's going to extract more from the outside than it previously did.
There is another reason that the coffee tastes better with this part.
The DE1 - and I have to explain a little bit how this works -
has a temperature probe that is just above the coffee puck.
And that is completely different from every other machine.
Every other machine out there measures water in a boiler or before it hits the coffee puck.
But no one has a temperature probe right on the coffee.
We're just about 2 millimeters above it.
And we dynamically change the temperature of the hot water to get the coffee to be infused at the temperature you asked for.
So if you ask for a 90°C infusion,
it's going to put water in maybe at 92°C, 93°C to start,
and then it'll measure the water temperature at the puck
and then increase or decrease the temperature of the water immediately, at 10 000 times a second.
Now, what's cool about that is you don't have to do anything.
You just say you want a 90°C extraction
and the machine just varies the water dynamically in order to do that.
You can see the Decent at work doing that if you make an espresso and you tap on the temperature chart.
The thick line shows you the temperature that is at the puck,
and there's a thin line line that shows you the input water temperature.
And that's moving like mad
and you don't have to do anything with that.
Okay, that's the background that I need to give you
to explain why this works better.
Because in order for that dynamic water temperature feature to work well,
we have to have accurate and fast readings of what the coffee puck temperature is.
And this is the problem with brass;
If you stick a temperature probe here
and through this little hole here right behind the shower screen,
if that is surrounded by brass, which is all at 90°C,
then when water hits the coffee puck and then kind of goes flowing around,
you're mostly going to be measuring the brass,
because the brass is really close to the temperature sensor.
And while you have flowing hot water around the temperature sensor,
the effect of the brass is overwhelming it.
And what that means is that
let's say you put some 90°C water on there
that then cools to 80°C, comes back up,
some of that reading will be measured by the temperature sensor,
but most of that water is actually going to cool the brass.
And as the brass cools down, then the temperature sensor will notice that.
So essentially, the brass is acting as a heat sink
causing what's called latency slowness of response of us measuring the temperature.
And any metal we use would have that effect.
So in order to solve that problem, we wanted to move to a plastic.
We wanted to move to something that had virtually no heatsink ability.
And that's what happens with this.
What the testers that have received this have said is
they don't know why but the shots are merely better.
And when you pull up the decent espresso chart for an espresso that is made with this,
you're going to be shocked,
because you're going to see that the temperature at the start of your espresso is now 3°C to 4°C lower than it has been.
And you're going to think is something wrong?
Nothing is wrong.
What's actually happening is you're finally actually seeing a much more accurate representation of the infusion.
It's no longer measuring the brass, it's now measuring the coffee.
And now the machine can near-instantaneously react to that coffee temperature.
What's happening is the Decent is putting in hotter water at the start,
much earlier than it did before,
because of that much more accurate and much lower latency.
And then, when the coffee puck does heat up, we don't end up overheating it,
because we now know that it's there.
And so the overall infusion is now faster to reach temperature
and stable at the temperature that you want.
There's one other thing,
and you may have seen uh Paul in some other videos making some shots with quite big temperature leaps, right?
82°C down to 72°C, those are huge leaps,
and I would say with the brass pieces, those are pretty hard to do.
And the reason is that if I put 80°C water in and I get the coffee puck up to 80°C,
and now I start dropping the temperature,
well,
that brass is still at 80°C.
And I only have about 20 seconds to try and drop the temperature,
and I'm getting these readings that are not correct, right?
I'm putting cooler water in and the brass is retaining that heat,
so I'm going to put even more cool water.
So that 80°C to 70°C drop is probably doing something quite different.
Probably, it's putting much cooler water than 70°C in to try and bring what it thinks the coffee puck is at.
With this now, temperature profiling is just so much more accurate,
and we're tasting it.
One last thing about these parts is
I have in other videos mentioned about the body of an espresso
and how much headspace there is above a coffee puck and how that affects things.
From version 1.0 to 1.1 that was our big change, where we removed a whole lot of headspace,
and this part as well removes a little bit more headspace.
So once you install these parts,
you will have exactly the same headspace above your coffee puck as on E61 machines.
We decided to just go with the E61 standard. It gives espressos that are very classic.
And if you want more headspace, you just go to a larger basket.
It's very hard to have less head space, unless you get a modification kit.
And so this, among other things, will also give you the effect of a modification to the shower screen.
There are shower screen adapter kits out there that lower into your basket.
I'm sure some people want their shower screen to go even deeper on the basket,
maybe to get super thick espressos,
but we decided to go with the E61 standard, which this part now implements.
So thanks for watching this video.
If you do get these parts and you find them better or worse, or you have any questions,
please, in the comments below, ask away and we will answer.
Thanks for watching.