In the photos, it certainly looks like the bubbles are bigger in the brown crema coloured areas. I agree that its unlikely to be the machine. If you think its too powerful, I assume you have steamed enough milk for 2 or more cappas at once? Do you you get the same result then? With a more powerful boiler, I stop stretching much earlier and it would seem you inject only the tiniest amount of air stopping as early as 80F indicated.

Good luck, Chris

I was also wondering if it is residual soap issue. It could be in the cup, the steam pitcher, the porta filter, or the filter basket, all of the above, or heaven forbid in the boiler water.

Failing that have you tested for the bubbles just with the milk, and just with coffee?

Good luck
Geoffrey

shadowfax wrote:Simple test... pour your steamed milk into an empty cup and let it sit for 5 minutes. Do you see the bubbles forming?

That's a good idea too.

I have been using a new source of RO water from a wine making store. Maybe he cleaned it recently or something like that. Hmmmm.....never thought of that.

Endo wrote:Here's a photo of what I'm talking about. Right photos is after 30 seconds (bubbles just starting), left photo is after 3 minutes (yuk)

Three minutes is a long time for a drink to sit, but I have seen macro bubbles like the photo on the right. I agree with Chris, you're overstretching.

Here's an easy test: Get a big pitcher (say 32 ounces) ice cold from the freezer and steam with 12 ounces of milk. That will give you tons of time to finesse the stretching and texturizing. Stretch the volume by 25%. Let the milk sit for around 20-30 seconds, then thunk and swirl it high up the sides of the pitcher (the "inverted cone" should be at least 3" deep). It helps to put the pitcher on the countertop and move it in a circular pattern to reduce the risk of spilling due to nervousness. Try Bronwen's trick, i.e., pour a little into the cup, swirl and thunk the cup just like the pitcher, then pour the rest.

While it's a long shot, another possibility is the crema is degassing. In that case, grind the coffee and let it sit a few minutes. I know it goes against the principle that ground coffee stales in seconds, but it does flatten out the crema of uber fresh coffees.

my money is on dirty pitchers. but even if it isnt dirty pitchers just rinsing them is not good enough. try this first and if it doesnt fix it then move on to the other things. change one variable see the result, move on.

it could be any of the other suggestions but he said he just rinses so its time to clean them for the sake of cleaning them even if the foam is nice and stable.

jon

My pitcher cleaning routine: I mix a bit of joe glo with warm water in a soap dispenser next to the sink by my machine. I don't recall the exact concentration, but it's pretty high without making the foam overflow as it mixes. I put a couple of pumps in my pitcher after rinsing out the milk, and purge water from the steam boiler into the pitcher, and swish that around. I pour that down the machine's drip tray, and it helps resist the buildup of nasty crap in the tray/tube. It's about as difficult as rinsing thoroughly, but has added benefits. Of course you have to rinse the pitcher out with cold water after, or you get a really hot pitcher. Seems to keep the nasty stuff out, and seems preferable to using a scented dish soap.

Drink faster....

Endo wrote:I'm pretty sure at this point it's related to excessive steam jet velocity and flow rate during the stretching phase.

Given that this isn't a problem steaming on (for example) a 3 grp Linea.... it seems highly unlikely that it's a problem with your machine.

Seriously... I've trained a lot of baristas. I've seen the exact thing your photo shows on multiple occasions.

Honestly, as Dan once said - "the problem is almost always on the handle side of the portafilter."

It's well known that everything about an espresso is fast. It extracts quicker than any other method, and extracts as a wonderful mixture of bubbles and liquid. It begins to separate even as it the extraction continues, and it's so delicate that even transferring it from one cup to another diminishes its body severely.

The same is true of even perfectly textured milk. Give it a few minutes and the foam (microfoam though it is) will rise to the top and stiffen. Of course, swirling and tapping actually works (at least to some extent) for foamed milk, hence Chris' 'controversial' mantra, "milk can wait for espresso; espresso cannot wait for milk" (I've been schooled before ).

Of course, having a machine that can steam 3-5 oz of milk in ~20 s and brew a shot at the same time allows you to avoid that dilemma altogether, and Endo is blessed to have such a machine. In general pouring a cappuccino extends the life of the crema atop the foam by somewhat more than it would be as a straight shot, but... a cappuccino is still a time-sensitive drink if you want to experience it at its finest (On the other hand, some may prefer to let the milk sit for a few seconds before pouring a milk drink, particularly a cappuccino).

Which isn't to say that Endo doesn't have a real problem that ought to be solved, however. Endo, as I mentioned before, I suspect your milk steaming is good enough--at least not the cause of the problem you're dealing with, IMO. I'm pulling shots of Mike Phillip's USBC blend, Bolivia Anjilanaka, this week (really, really nice cup, straight and in a short cappuccino), and it started acting up as you've photographed above on Wednesday (when steaming during the shot and finishing a few seconds after it ends). I tried a few of the suggestions on here (including Chris' to steam first and swirl aggressively, cleaning all my equipment thoroughly, steaming cooler than usual AND hotter than usual, and letting the milk sit for 5 minutes and checking for macro bubbles). None of those helped; the thing that did it for me was swirling and tapping the shot right after pulling it to settle the crema well. Of course, Bronwen (mentioned in the first reply, IIRC) would pour a little dollop of milk in before doing this, but I didn't find that necessary. You might try it without the dollop. Or maybe your problem only seems similar to what's happening on my setup, and it will be something entirely different. Stand back, everyone! Endo has to try SCIENCE!

...and remember, you can always just drink faster as Dave has reminded.

Nicholas,

I think you nailed it. I'm now convinced it has nothing to do with milk steaming technique. In fact, it has nothing to do with the microfoam. Have a look at this latest picture (after a 1.5 minute rest). I even added a bit of microfoam first and swirled as recommended.



The microfoam in the espresso cup on the right (from the same pitcher) stays perfect. Even the milk in the rosetta on the left is fine. The bubbles are only in the dark parts of the Latte.

So is it crema? Is it the water? Is it the way I pour the rosetta? Is it the shot temperature or pressure?

Seems I'll need to experiment more with the shot itself in order to solve this mystery.