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"#p19736 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"#p19741 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"#p19801 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%].

@"hornbyben"#p19814 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.

This seems appropriate… [upl-image-preview url=https://i.imgur.com/9EobqN4.png]

> @"DavecUK"#p19818 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"#p19820 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.

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

Dry steam from a single boiler

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!

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