I got an email yesterday with the following question for a reader, and thought I'd share my thoughts here in case other readers are having the same difficulty frothing their milk with an Aerolatte whisk.

Hi John, I enjoy your blog. I have traveled to Australia a few times, and am looking for ways to re-create the perfect flat white. Although I'm new to espresso machines, I have no trouble pulling great double shots (same Gaggia espresso maker and Breville bean grinder that you have, using Victrola Triborough [beans]), but I'm finding the milk frothing to be difficult using the whisk method. What I'm finding is that I can get the proper 2x volumetric expansion with lots of foam (looks just like the picture of the milk in your glass, how to make milk for espresso drinks), but after I swirl the flask for ~20 seconds and try to fold the foam into the milk with a spoon, and pour off the milk into the cup, the milk from the bottom of the flask seems thin and normal rather than the velvety characteristic of flat whites. The result is something more like a cappuccino or an au lait--the espresso turns to cream-colored coffee rather than velvety throughout. For some reason, the foam doesn't seem to be mixing well with the more liquidity milk on the bottom. Any suggestions on how to make the poured milk more consistently velvety? Thanks, PC

Thanks for your question, PC. I have experienced the same problem myself in the past, and essentially it's because you haven't actually created enough foam, or haven't sufficiently blended the foam on the top into the milk at the bottom. The milk from the bottom that goes into a flat white isn't totally foam-free. Mixing the milk at the bottom into the foam on the top is best done, I find, by using a large teaspoon, rather than swirling the milk. Lift the milk from the bottom up into the foam, and push the foam from the top down into the milk at the bottom in a circular motion. If normal stirring can be considered to be stirring in a horizontal plane, then what I'm trying to describe is like stirring in a vertical plane. Hopefully you get what I mean.

Here are a few tips of things I have discovered over time that have helped me produce plenty of foam in the milk using an Aerolatte. Hopefully these will resolve this issue for you:

• Standard AA batteries are rated at 1500 milliamps (mAh) maximum. I discovered long ago that fresh batteries with a higher milliamp rating make a huge difference as the whisk runs faster. I changed to rechargeable batteries with a high 2000 mAh rating some time ago now and now get a lot more wizz for my buck. (I use Sanyo eneloop AA 2000mAh rechargeable, but any rechargeable 2000 mAh batteries you can get for a good price will do you well). Recharge the batteries as soon as you detect any slow down in the speed of the whisk. I find the "eneloops" last for a month or more before detecting any slowdown. The higher amperage also appears not to have done any damage to my Aerolatte as the one I am using currently is already over 2 years old and going strong.
• Use no-fat or 1% milk - the lower the fat content, the better for foaming
•  Another thing that I found is that lactose-free milk, for whatever reason, produces a lot more foam. You could try using that. Personally I find it actually produces too much foam for a flat-white, though. It is perfect milk to use if you're making cappuccinos, however.
• When whisking the milk, move the whisk slowly around the mug in the opposite direction of the circular motion of the milk. This adds additional resistance and helps creates more foam. 
• One other thing to check is that you stop the whisk before you take it out of the milk. If you are lifting it out and turning it off at the same time, you will end up with large air bubbles on top of your milk, which is something you want to avoid.

Hopefully these tips will help you out. In a nutshell, get as much foam as possible, mix it into the milk at the bottom by stirring vertically, pour what should be slightly-foamed milk from the bottom of your mug into your espresso at one side (not the center), holding back the lighter foam at the top with your large teaspoon. All going well you should be able to re-live your "flat white" experience from Downunder. Once again, thanks for your question and for following ECS.

For other readers who want to try foaming their milk for lattes, cappuccinos, or flat-whites, see how to make milk for espresso drinks.