No preinfusion on this one.
Hey there Matt! We’re tickled that you are just as excited about Steam and the addition of volumetrics as we are! p.s. we love this thread.
Good day to all of you and thank you for engaging so openly with the launch of Slayer Steam. I’m Sarah Dooley and I work primarily in Marketing at Slayer, although R&D is where I’ve spent the last 6 months learning and testing.
Let me begin by saying that we recognize there are a lot of questions. Our research has produced solid answers, but we will conduct further tests if we come up short in any conversation. You all deserve the truth.
I want to take this one topic at a time, starting with dry steam / dilution.
The core technology inside of Slayer Steam is a compact super-heater, which we call the Vaporizer. As steam leaves the boiler, it passes through the Vaporizer and is flash-heated at high temperatures to remove water, resulting in a dry vapor. Our steam tank is usually set to around 250º F; the Vaporizer is much hotter, producing steam that registers at 360º F. (That’s the output temperature, not the element setting.) Compare this with a conventional system, which produces steam that registers around 212º F at the wand.
The result is a drier steam that is nearly invisible. Counter-intuitively, perhaps, drier steam results in slower heating because the liquid water in conventional systems actually helps to transfer heat. When compared to Slayer Espresso, Slayer Steam takes 3-4 seconds longer to bring 150 mL of whole milk to 130º F.
So, this dry steam uses less liquid to heat milk. This brings us to the topic of dilution. Simply put, we don’t “water down” milk as much as most machines do. Conventional systems add an average mass of 10% liquid water back to the milk. Slayer Steam averages 6.5%. Does a difference of 3.5% really matter? We think so.
SCAA and SCAE Gold Cup Brewing Standards tell us there is a preferred flavor experience window that is just around 19-22% extraction. That’s a window of 4%. Swing that pendulum just 3.5% under or over and you can write yourself out of winning the brewers cup or, for what it’s worth, hitting the masses where their palates want flavor to be.
You can taste the difference with a simple test: heat two airtight bags of milk via sous vide, then dilute one with 3.5% of its mass in water. Similarly, anyone who enjoys scotch (like me) will note that adding just a few drops of water to a very complex scotch will change the experience completely.
We will be the first to say that we did not make all of these conclusions on our own. Over the last few months, we employed three outstanding food and coffee professionals to make sure that we weren’t “drinking our own Kool-Aid”. We believe that these are real changes, which will make a real difference to our guests cup experience.
Thanks for participating in this with us; more info is coming soon. For now, let’s keep talking about dry steam and dilution!
My perspective on this is a little different (apologies in advance for the brain dump).
It’s true, there is a large increase in enthalpy associated with the “change of phase” from liquid to vapour (which is because the molecules that escape the liquid are those with the greatest kinetic energy). However, I’m not entirely sure it is valid (or relevant) to say the steam changes phase back to liquid and “realeases” that energy when it is added to the milk.
I find it easier to think in terms of the specific enthalpy (the enthalpy per unit mass). Consider the hot steam and cold milk separately - each has it’s own specific enthalpy (related to it’s temperature). When the steam is mixed into the milk, the temperature of the resulting mixture is a function of the specific enthalpy of the mixture - which is approximately equal to the mass weighted average of the specific enthalpies of the milk and steam. What, if anything, changes phase (and at what temperature this might occur) is essentially irrelevant.
A few thoughts:
Saying a superheater removes water is potentially misleading. Dry steam (whether superheated or saturated) is 100% water, it’s just that there is no liquid phase present. It’s more than likely all of the water entering the superheater ends up in your milk.
Superheated steam is dry steam which has been heated to greater than the boiling point (at a given pressure). It has a greater specific enthalpy than either wet or dry saturated steam which is why you need less of it (by mass) to heat your milk.
As other have mentioned above, I’m also not entirely convinced about caramelisation occurring (I would be interested to know if this is just a theory, or if it has been verified analytically).
Regarding the reports that heating milk takes longer with the superheater on:
There is no reason I can think of that superheated steam would transfer heat more slowly to the milk than saturated steam, in the case of direct steam injection. I’m quite sure conduction is not a factor.
One plausible explanation is the superheated steam having a lower density than saturated steam (wet or dry) at the same pressure:
Assuming the same steam tip, I would expect the volumetric flowrate to be close to that with saturated steam and the mass flowrate would therefore be lower.
My quick and dirty back of the envelope calc (which assumes the equal volumetric flowrate) suggested it would take around 10% longer to heat milk to the same temperature (comparing superheated steam at 180C to wet 90% steam at 125C).
- The slower heating could also perhaps be partly responsible for the reported improvements in milk texture (in addition to the reduction in dilution):
- Bubbles are broken up by shear stress, which is influenced steam velocity (and thus volumetric flowrate).
- Exposure to approximately the same level of shear stress over a longer period, might perhaps result in smaller bubbles.
I believe it does have pre-infusion but it is of the mechanical variety not through variable flow control. The Slayer Espresso is still the machine for profiling espresso. The Slayer Steam combines the traditional consistency of pre-infusion, flat pressure & volumetric dosing with epic milk from the new ‘vaporizer’ super heater. I think it is aimed for specialty coffee houses with high milk volume.
Im guessing you can still adjust the flat pressure at the pump - @sarahdooley, is this all correct?
Hey there @AndrewB and @Bayard, I’m happy to interject a few facts. You are correct Andrew, our newest machine is volumetric however there is not a programmable pre-infusion feature and you can adjust the pressure very simply at the pump.
For added clarity the term pressure profiling was used, Slayer Espresso has a two phase water delivery system. In phase one an adjustable needle valve delivers water pre-pump, to the coffee bed. This is the bloom phase of extraction to saturate the puck thoroughly before pressure is added to the system. Much like what we all do when brewing pour-over or setting a pre-wet phase on our brewers. Phase two engages the pump at the pressure you determine is right for the coffee.
Does that add clarity?
I believe you’re underestimating the latent heat of condensation. It’s more than 50% of the thermal transfer. Without it, you’d need steam at 680C, which this machine certainly doesn’t do.
I think the idea that “condensation” of the bulk vapour occurs at some point, and that this point is when most of the heat transfer occurs, is somewhat inconsistent with the physical reality.
If we were indirectly heating the milk (say, with heat transferred through the walls of a heat exchanger tube) then you’d be (mostly) right. But that isn’t what is happening in our case. We are adding the hot steam directly to the milk and the mode of heat transfer is entirely different (because it also involves mass transfer).
My way of thinking about it is as follows (it’s somewhat oversimplified, but useful enough):
- Temperature can be thought of as a measure of the average kinetic energy of the molecules in a fluid (not all molecules have the same kinetic energy).
- The water molecules in the steam are moving much much faster than those in the milk.
- When steam is injected into to the milk, water molecules from the steam will cross the liquid / vapour interface (which strictly speaking, is condensation).
- Each molecule which crosses the interface:
a. depletes the mass of the steam vapour
b. increases the mass of the milk
c. increases the average kinetic energy of the milk (increasing the temperature)
d. then interacts with molecules in the milk, transferring some of it’s kinetic energy to them (changing the distribution, but not the average and thus not the temperature)
My assumption is that this happens very rapidly and that condensation as it is commonly thought of (bulk steam condensing into liquid droplets) is not required to transfer heat to the milk.
That said, I could be completely wrong; I’m certainly no expert in thermodynamics or kinetic theory.
It is interesting to note that the vapour phase exists even below the boiling point and that looking at steam table data it appears the specific enthalpy of the vapour phase does not change markedly when you cross the boiling point curve (there is a general trend increasing with temperature).
Boiling is only relevant because there is a significant increase in the amount of vapour (relative to liquid). You can calculate the amount of steam mass required to heat a given mass of water, by accounting for the difference in specific enthalpy between the initial and final condition. The result should be numerically equivalent to using the specific heat capacity (i.e. change in specific enthalpy per unit temperature ) and the latent heat of condensation (i.e. change in specific enthalpy per unit mass condensed).
It may also interest you to know it is theoretically possible to reach the superheated condition without going through the boiling phase change at all - it does require pressurising the water to greater than it’s critical pressure (~ 221 bara from memory) prior to heating though.
Have you read this? The latent heat of condensation is literally doing half the work.
@MattPerger @DIYCoffeeGuy where can someone learn all of this science? can it simply be googled or does it have to be studied somewhat academically? this chat is enthralling but I can’t say I understand the majority of the terminology
It’s all pretty simple. Definitely not degree-level. I only did high school chemistry, physics and engineering.
Best bet is to look at explainer videos for specific heat, latent heat of condensation, and thermal equilibrium.
What I find most curious is that Slayer has decided to split their machine offerings in such a specific way.
High volume cafe that relies mostly on ‘press a button and go’ :: get the Steam.
But where does this leave the Slayer Espresso? Is it now considered a machine mostly specialized in extracting different flavors etc from coffee?
Is one or the other better for a cafe with a serious coffee program? Or are they just ‘different’?
Another thought to throw out to you fine folks - when it comes down to it, which (or what) makes the better milk-based drink? An espresso with all of the potential nuances brought out in a variety of different way (a la Slayer Espresso and its water debit) or is the texture/taste of the milk more important? Sadly the machines are geared/marketed towards preferring one over the other … Is a combination the best?
I realize I’m asking theoretically, and there is probably no right or wrong answer, but I’m hoping it creates discussion around those milk-based drinks (which consistently seem to take a back seat, even tho I’m sure the vast majority of cafes serve far more of these compared to straight espresso).
it does seem odd that they havent created a machine that incorporates both technologies, perhaps it’s too expensive to manufacture and therefore too expensive to sell, or because it’s just not possible.
But when it comes to milk based drinks, I’m going down the extraction route (slayer espresso). you can still produce extremely high quality milk on a La Marzocco or a VA or a Simonelli, I think it’s better to have a coffee that is a 9/10 paired with 8/10 milk, rather than milk that’s 9/10 paired with 8/10 espresso.
I believe it’s always about having an amazing espresso to work with, rather than amazing milk, of course there’s asterisks involved with this, such as the quality of milk in terms of who provides it, milk from companies such as Estate will be leaps and bounds better than a supermarket brand. I think it should be Great espresso accompanied by good milk, rather than great milk-good espresso (I know I practically said this in the previous paragraph)
We also asked these questions, once again @sarahdooley, please interject if my understanding isn’t accurate. The Slayer Steam is aimed to sit next to all the machines like the LM Linea with great quality repeatable espresso (flat pressure & volumetrics) but also look to highlight previously unlocked flavour in the milk. Ive loved listening to the milk conversations in this thread (defo need to polish up on my ‘high school’ chemistry!), i’m not 100% sure why/how it tastes better but it did at the show. There is also less ‘seepage’ with the better structure in the steamed milk.
So, yes it would be great to have the tech from both machines rolled into one but alas, the Slayer Espresso with volumetrics does not yet exist (lets hope Jason has future plans for this). I see the Slayer Steam as a machine that will work in business’ that don’t want to to leave the yield open as a variable. You still get great espresso with the same style of gicleur/jet as an LM Linea combined with awesome milk - all at a lower price than the Slayer Espresso.
I also discovered another simple yet effective feature on Friday - the Slayer Steams new pressure regulation. Regardless of how many groups are calling for water or the boiler filling, the Slayer Steam has a pressure regulator after the pump that means you will have a consistent pressure at the groups. For those that want to play with different extraction pressures it will be a simple twist of the regulator rather than an adjustment at the pump.
That pressure regulation feature truly sounds pretty great! It could be a pretty big deal to have 2 or 3 groups with different flat pressure profiles … Or maybe not - who knows?! Either way it’s something that deserves some experimenting!
I think we all wish both machines could be combined into one, but it just might be too expensive at this point. Not to mention cramming all of that into such beautiful profiles could be a huge challenge, as well.
As far as volumetric on a Slayer Espresso - I believe the SureShot system by Ace Services seems to come pretty close. An added timer and some added features that essentially turn the machine as close to volumetric as can be (albeit based on time instead of volume, but with a flat 9 bar it should be fairly accurate shot-to-shot). I’m thinking of having that system installed on our 2 Group Slayer Espresso just to see what it can do! Could be nearly the best of both worlds (albeit without new Steam capabilities).
I didn’t realize the Steam would ring in a fair amount under in terms of cost - I’ll have to email Elyse and look into that!
I’m excited to try a Capp from the Steam, there is no doubt about that … But I think it’ll be awhile until I come across a cafe that might be stocking one here in Toronto.
Thank you for bringing us back into this conversation @AndrewB.
Our goals with this machine are incredibly simple. After reviewing very high volume coffee and milk preparation going down in Australia, it seemed very obvious that we needed to put variable controls in place in the form of flow meter technology. Volumetrics just make sense. Classic pump driven water with a very easy access point for changing that base pressure are also present on this machine. Secondly, milk has long been done well, but that clearly doesn’t mean there is no room for “greatness”. Turns out our hypothesis was correct and there is a positive change to aromatic, flavor and texture with Vaporizer technology in both dairy and alternative substitutes.
I’d like to dwell a little on this topic. As we taste with more specialized tasters we all agree there is an undeniable aromatic change occurring, a new complexity in sweetness is also present in the flavor experience and the creaminess of the butterfat just lingers for days. The texture of milk and non- dairy alternatives (even more noticeable) feels more round and is cleaner, this particular detail only intensifies as the quality of milk increases (logically). I invite you to visit me here in Seattle to experience these differences. Send me an email, I’ll make it happen.
Gals and guys, scientific facts in the form of “hard evidence” towards proving a possible chemical change has been a hard detail to source. This requires a very stable test environment, incredibly fancy tools (to capture multiple variables), the right questions and a quest towards answers. I will continue to look for an appropriate partner for this service.
We have noticed across many many comparison tests that our machine’s Vaporizer technology does not put as much water weight back into the steam pitcher during the steam cycle. We’re working towards a visual example for this to showcase the staying power of latte art and the meaning of a new term in our vocabulary, seepage.
The million dollar question; “when will there be a Slayer & Steam mashup machine, combining the technologies of flavor profiling via needle valve and Vaporizer technology?” It literally took me three minutes into my first conversation with Jason about the new technology to as that very question. He smiled and said, “Listen, right now I’m about to launch technology that will change the world of milk and coffee, let me bask in the glory of this accomplishment Sarah”.
Hey Sarah, Thanks for all your information on here regarding the Steam.
I’m hoping you can enlighten me on a few different topics regarding the Steam as I have just ordered one for my cafe and am nervous as I have heard quite a few worrying reviews.
These reviews (anecdotal) have suggested that -
Temp control is extremely unstable due to heat exchange
steam wand shut off is very delayed making perfect milk very difficult
flow rate is too high resulting in aftermarket restrictors having to be put in place
shower screens are too high which result in higher cases of channeling.
Like I say, this is all just what I have heard from a few crew over here in West Australia that have used the machines. I also find it a little concerning that I cannot find a in depth manual anywhere on the internet and my friends at Someday Cafe Perth didn’t even receive a manual when their coffee machine was ordered.
I know this sounds like I am ragging on the Slayer brand but the Espresso V3 has made some of the most incredible tasting coffee I have tasted and I just want to know what I am buying.
Hey there Isaac,
The first thing I’d like to do is thank you for the preface, I don’t here a ragging tone at all in your comments. I’d also like to add some of the concerns you have were actually real while others were odd one off cases. Without making a ton of excuses, I will state launching a new product is hard. I’ve had the privilege of being on board with incredible companies to develop and launch new products. There’s always a hope for a perfect product but they don’t start out in that realm. Ask La Marzocco, Baratza, Mavam, Synesso or any manufacturer for that matter how many tweaks and changes they made to what they hoped was a final product, after launch. Consumers and professionals are the best fine tuners and believe you me, they are loud and clear with expectations. We welcome and love that feedback.
Slayer is a better company today in so many ways than they were 10 years ago and believe it or not even in the past year we have really turned up the QC measures and support team to ensure better solutions for all. But you didn’t write me to get a bunch of excuses, you want answers to your questions Isaac and I will help you to the best of my ability. Additional questions are best explained by Nate or Nelson with Slayer Support, firstname.lastname@example.org.
Temp control- I’m assuming you are writing towards the espresso extraction? I’ll revisit the firmware development and my performance notes to share very specific feedback in a different reply. (Friday fever What I do remember is the system is not your average, run of the mill heat exchange setup. But for the sake of getting you some answers and not scattered memories it’s a savvy and detailed system that is actually stable when tuned properly.
Steam wand delay- yes, there is a delay, for most it is manageable in bar flow adjustment. That doesn’t mean we have dismissed the issue of delayed shutoff and tolerate it. We are aware and working on shortening that delay. Of course Isaac, there are outlying issues where the delay is extreme and while I can’t speak for the support team, I know they hustle to troubleshoot those issues.
flow rate is too high resulting in after market restrictors- if this is relating to delay in the steam shut-off, maybe but I couldn’t name a specific fix here that relates to that statement. I’d have to check in with our support team for proper context.
shower screens are too high which results in channeling- that is news to me. I brew on both Slayer Espresso and Slayer Steam and channeling happens when I overdose or don’t follow best practices for grind, dose, tamp. I’m happy to followup with our support team to be certain.
With regards to the manual, we did have many delays in having a completed manual upon shipping the first few batches of Slayer Steam. Delays in production, changes and advancements in crating and accessories also meant delays in copy and changes to our manual. That is no longer an issue.
I’m happy to get you more detailed answers and share my email with you for faster responses once your machine arrives. Please excuse the typos and such. My potential freckles are calling, summer is finally here in Seattle and it’s kind of glorious outside.
thanks for getting in touch, glad I caught this before the weekend- Sarah
p.s. email@example.com for faster replies, BH is fine if you don’t want to leave this platform.
Is there an abnormally long distance between the steam valve and the steam tip, or is the wand ID larger than on other models?
The only three factors I can think of which would influence the steam wand shutoff time (ignoring the valve itself) are:
- The volume between the valve and the tip (larger volume = more delay)
- The density of the steam (greater density = more delay)
- The steam tip hole area / geometry (smaller = more delay)
What shop are you at in Dublin? I did get to try 3fe when I was there in 2015. Amazing stuff.