Could just simply be the Crema, doing what it does.. Dissipating.

If you pull a shot, and let it sit, the crema goes away.. eventually completely.

It is an emulsion, and not EVERY emulsion is stable. A vinaigrette, properly made, is an emulsion. Let that sit and you have, Oil.. Vinegar.. Herbs/spices.. separated from one another. Mayo on the other hand is a bit more stable.

Something I noticed a while back.. If you pull a shot of pretty fresh coffee, say, about 3, maybe 4 days PR, and right after you pull it, hold it up to your ear.. Sometimes you can hear almost what sounds like the "head" of soda settling,, albeit much quieter.

So, its possible this is whats happening, but because of the milk, you end up with the larger bubbles, which eventually pop, but take longer then crema because of the fat in the milk.


Its also possible Im wrong.

Tomorrow I'll try doing some shots with some older coffee to see if it's the freshness that's doing it. I'll also try letting a shot sit for 5 minutes before adding the microfoam.

Obviously, none of these are actual solutions, but his should let me know if freshness or crema is the source of the problem.

Hi, long time lurker first time poster here

My family has had an Oscar for a week now, and as I get closer to achieving microfoam (at first) the more I get these ugly bubbles. Today I stared at the bubbles as they formed and they only formed where the crema had mixed with the milk.

I tried swirling the espresso around to no effect. I also tried stretching less aggressively, any less and I don't have any steam pressure to form bubbles without lifting the steam tip out of the milk and I don't think the espresso is too fresh as fresh beans are very hard to come by here and they are probably a month old now.

Any pointers would be appreciated as I find this quite baffling and the bubbles are frankly putting me off my coffee.

Graham

An Oscar should have plenty of power to microfoam. You are probably lifting the steam wand too far. It should not really break the surface but dance right on the edge. If the tip breaches the surface, boom, bubbles. Your coffee is also way past its prime at a month old. I have a few steaming videos out there somewhere. I will see if I can find a few and post them.

I never lift the steam wand tip above the surface of the milk. My most recent attempt this morning had no visible bubbles from the stretching stage. It is always just a little bit below and I keep it at a position where I can hear the "tsk tsk" sound and after I get the volume I am after, I push it in and I try to get a whirpool with the roaring sound but quite often I cannot get the vortex to full strength before the milk comes up to temperature.

Yea I am aware that the beans are not good enough but unfortunately that is close to the best I can do. I don't know of any local specialty roasters and these are imported. Since they are so old, would I be correct in eliminating the degassing caused by overly fresh beans as a potential cause for the problem?

Thanks for your quick reply and I would appreciate those videos.

Sounds about right. From the Vibiemme Domobar Super review:

Thanks for that.

Hi guys,

Drink faster....

I'd say the same, cappas are not there to sit and watch them, especially if the milk is around 60*C the whole thing gets cold quite quickly and is just about right to drink straight away after pouring.

I've seen the same thing happen to me, even though the milk was velvet smooth in the pitcher, no bigger (or even small) bubbles whatsoever. It might be a good idea to do what someone already suggested, mix a bit of milk with the espresso before pouring in the rest, or skim of the crema.

Regards,
dsc.

I've seen the same thing happen to me, even though the milk was velvet smooth in the pitcher, no bigger (or even small) bubbles whatsoever.

Did you ever find out what caused it? I've had some very good cappuccinos and some terrible ones but none of them have ever resulted in this so I know that this is not completely normal and can be worked out. I don't really know long I take to drink one completely but the microfoam is usually still there are the base when I'm done so I don't think I'm waiting unusually long.

Thanks for the advice about mixing some of the milk in at the beginning, I'll give that one a go as it's the only solution I haven't tried yet.