I’ve always purged the water from the steam wand on my Silvia before steaming milk, but it’s always hard to be sure when you should stop purging and start steaming. The other day I thought, why not open the steam valve and let all the water out before hitting the heat to steam temp button. This clears water out of the steam arm, and as the boiler isn’t at much pressure it doesn’t spray everywhere. When it reached steam temp I purged the line, and some more water came out, but a lot less than usual and the steam was noticeably dryer. I also found the texture of the micro foam to be better as well. Anyway, I haven’t ever seen this suggested before, so thought I’d share for those who use single boilers.

I’ll give it a go tomorrow morning, though I might need a coffee first before I remember….

Dusk let us know how you find it? My theory on why it improves the milk is that with less water there, you don’t get occasional more vigorous water and steam injections that entrain more air.

hornbyben Just tried it, there’s definitely a lot less water coming out so the steam looks much drier. I guess the easiest way to test would be to weigh the milk before and after steaming with each method to see how much water is added. I’ll give that a go tomorrow if I remember. In terms of milk quality, I’ll need to give it a few days as I’ve been away from home for a couple of months so I’m out of practice!

I tested how much water I am adding while steaming milk with my single boiler ECM Classika and I am usually between 12% and 13%

Evergreen88 I’ll try to remember to weigh mine in the morning for comparison. I’m sure you’re aware, but you will always add water when steaming. The reason you can heat milk so quickly is due to the energy released when steam condenses into water, not just the fact hot steam is going through the milk. Below is my attempt to calculate this for 120g of milk (my normal flat white): Physical constants: Specific heat capacity of milk: 3.93 kJ / kg.K Water enthalpy of condensation: -2257 kJ / kg (at atmospheric pressure) temp change required: 5°C to 60°C: 55°C Energy required to heat the milk: 3.93 kJ / kg.K * 55 K * 0.120 kg = 25.9 kJ Amount of water required to deliver this much energy through condensation 25.9 kJ / 2257 kJ/kg * 1000 g/kg = 11.5 g So even with perfectly dry steam, you would expect 11.5 g of water to have been added to 120g of milk due to the physics of how heating with steam works (I.e. 10%].

Dry steam from a single boiler

DavecUK

hornbyben You may need to check your math sir!

Otherwise steam at 110C and steam at 140C put’s the same amount of water into the milk….which it won’t. It is temperature dependent.

In fairness though, the effect is not massive…because it’s not a theoretical system, but it’s there nonetheless.

CoyoteOldMan

DavecUK In fairness though, the effect is not massive

Less than 10% from 110 to 140 °C - water enthalpy at saturation at 110 °C is ~-450 kJ/kg, at 140 °C it is ~-600 kJ/kg and at 60 °C it is ~-250 kj/Kg. The differences are quite small relative to the condensation enthalpy. For an engineer, pretty much all the same… (speaking as an engineer - a long time ago, and my thermodynamics is definitely rusty)

(Sorry - don’t mean to nitpick; your comment just made me curious, and finding stuff on the internet is so easy vs. searching all over a book)

CoyoteOldMan

This seems appropriate…

hornbyben

CoyoteOldMan thanks for the build. I just wanted to understand the ballpark. I’m a chemist not a physicist, hence why I showed my working for those more appropriately trained.

hornbyben

So I measured. Doing it the normal way added 31g of water to 120g of milk. Purging before heating added 25g for the same amount of milk, so definitely an improvement

Evergreen88

hornbyben I measured again yesterday and I achieved a less impressive 16% increase in weight after steaming 337g of milk. I suspect a HX or a DB would get something in the region of 11-12% more consistently.

DavecUK

The weaker the steam and lower the temp, the more liquid is added. I realise there is expansion but probably a large change in weight….something I might starting adding to any future reviews I do.

LMSC

DavecUK future reviews I do.

Are you hinting you will be reviewing Kafmasino One? 😂

DavecUK

LMSC Are you hinting you will be reviewing Kafmasino One? 😂

They did ask, but I simply don’t have the time to do it justice…I have been doing quite a few engineering reviews and other projects. I think that guy on YT is probably giving them the sort of thing they really want. My review might be quite a bit more in depth.

hornbyben

DavecUK that’s a shame. It’s always good to see one of your in depth reviews.

jrling

hornbyben - have only just come across the Kafmasino One and must say that I was impressed with the professionally produced software and taking the good bits of the Decent approach to the hardware and profiling parameters available. At c.£1,000 with Bluetooth paired scales it seems pretty competitive to the £3,260 for Decent DE1 currently. Two years on from release, it must have settled down fixing any issues? Has DavecUK been persuaded to do a full review?

dfk41

jrling Has it actually been released yet? I thought it was just at the testing stage still though am happy to be wrong

DavecUK

jrling DavecUK been persuaded to do a full review?

I think they lost interest once they realised it would be an open and honest review. I also think they only wanted something for the crowd funding. In which case it was not something I wanted to be a part of. I am interested in showcasing good products, not making a company money.

To my mind it’s based on a very cheap machine, with largely untried and slightly copied software ideas.

jrling

Oh yes, I think you are right. https://kafmasino.com/shop/kafmasino-one-coffee-machine/ Pricing on their site is Euros 1,060 and taking pre-orders for quoted delivery in May 2024.

jrling

Absolutely understand your reluctance hearing that. Have to say that the Spanish brothers do seem to be making a genuine attempt to bring a much cheaper alternative to the Decent DE1 to market and bravo to them for trying. As you say, the cheap base machine is a bit of a let down, but presumably is the only way to get a Eur 1,000 (ish) machine to market. The software is everything to this machine and so let’s see how it performs in a public released machine. Looks pretty much like Decent’s software and you never know, but it might be an improvement!