I have been fine tuning the milk frothing over the last few weeks, and I am almost there. My reference standard as how it is supposed to look like is the hospital cafeteria that happens to make the best cappuccino in town using a very large expensive machine manned by someone who really knows what they are doing.
The bubbles are almost too small to see, and this makes a creamy thick paint like foam that can be poured over the brim of the cup. The nozzle of the steamer is over a cm below the milk level in a large steel jug that swirls the milk. Of course with the Otto you are not going to get that sort of power. Other equally expensive machines in town manned by people who do not know what they are doing still manage to mess up this step. So after this preamble here is what I have found with trial and error on the Otto.
If the coffee grind basket combination is not correct and there is not enough steam pressure, the milk will fail no matter what you do. If you have that right, gradually lower the nozzle. If it is just skimming the top of the milk, you end up with large bubbles and lots of froth, and can probably stretch the milk to the top with too much air almost immediately. This is not what you want. This causes the sputter sound as well as a mess.
Lowering the nozzle further starts to create smaller bubbles that you can still easily see and a slurping sound as milk and air seem to get sucked together. You can still stretch the milk to three times its volume and then tap down later. The position of the nozzle is harder to judge later in the procedure because it is sitting in all the loose foam. This is still not correct. The hospital cafeteria machine did not look likes this either.
Lower the nozzle further to the point of where the slurping sound just disappears and just hisses instead creates fine micro bubbles that are hard to see and milk the stretches to 1 and half times its volume. You do not need to tamp this down later, and looks like thick paint. This is what you want.
Putting to nozzle too low heats up the milk but does not create any bubbles. Just like the coffee grind basket combination to create crema has a narrow sweet spot; the milk frothing technique has an equally narrow sweet spot, but with some practice is doable.
those times are close to what I am doing too, its nice to know I am in the vicinity.
My grinder is not getting the beans as fine I would like, sourcing a new grinder to get an better espresso grind which may help with consistency in steam pressure.
The post on milk texturing from Mikelomb is excellent, I will follow this to see how it works for me.
Thanks! Good to know that I am in step with others. However, I feel that my times are a little long compared to the user manual. Perhaps my element heat is a touch low. I might experiment and see if a higher heat reduces my times.
I agree that mikelomb's post on milk frothing is very good. I have found these two sites a great help also.
I prefer lattes to cappuccinos, so I texture for a relatively short time. If you really want a lot of foam, put the pitcher in the freezer first and texture until closer to 40°C. I understand there is a point (temperature-wise) where you can't introduce any more texture into the milk. Cooling the pitcher down gives you more time to do this I understand.