What is the science behind Latte Art? I understand that without crema and microfoam, latte art will not be possible. I've seen numerous clips and read heaps of articles on the internet but is there a definite recipe for creating the perfect latte art and what is the science behind it? I am quite good with the heart shape but the rosetta is still elusive. Can anyone tell me why the milk sink to the bottom of the cup lifting the crema when you first pour and then the foam starts forming when the cup is about 2/3 full, and how does the foam stay on top of the crema? If air has been incorporated into the milk in the form of microfoam and the steamed milk in the pitcher has a uniform consistency, what makes the milk behave different in the same cup? I hope I don't sound stupid here and I hope by understanding the science behind it, I can improve on my technique in Latte Art!

Thanks heaps!

Funny aye it's harder for me to do a heart than a rosetta
Well I'm not aware of the science behind latte art, but I would like to tell my point of view about that. In my view when you create the microfoam and the crema, the milk become more dense and heavy. If your milk is not well textured you won't be able to do Latte Art because the milk will not be dense enough for create a pattern. About the milk sinking at the bottom of the cup, I guess it's due to the weight of the milk compared to the coffee weight. After being steamed the milk become heavier than the coffee that is why I believe the milk sink in the first place (the weight). As you said the foam starts forming when the cup is about 2/3 full, so basically you should have 1/3 of coffee and 2/3 of milk. If the milk start forming at 2/3 it means that there is enough milk for starting your pattern. I believe the reason why the milk stay on the top of the crema during the third step is that you have already " a bed " of milk underneath the crema which push the milk up until you fill up your cup. To sum up the milk rising underneath the coffee allows you to create your pattern(density), the milk has to be flawless (dense and heavy enough) for allowing you to create a proper latte art.

Well I think I don't answered to your question, there is nothing about science in my post, it's more about the common sense but perhaps it will help a bit ( i'm a new barista crazy of latte art so I hope others will contribute to this topic which is interesting )

ps: english is not my frist language, sorry for the mistakes I hope you'll be able to understand what I'm saying^^

+1 for your post

When you pour with high speed/height the milk travels further down in to the coffee/water and mixes - with the lighter/foamier element seperating and rising to the top, while keeping the crema on top of it.

Then you reduce the height/speed of the pour so that the poured foam now does not have enough velocity to break through the foam cap and start pouring the pattern (some milk still seperates from the foam here and then drops down below the foam to a certain degree) - you can pull the middle of the rosetta at the end for example by increasing the speed/height again so that that stream acts like a knife running up through the pattern you have laid out to finish it off nicely.

In a nutshell, and in theory. In practive I have had quite a few shaky rosettas with the Gaggia Baby with panarello/turbo wand!! lol

Here's an out of the way link or two

Reading these drives home an important point: cappa foam is better when it isn't stable. You can use a high speed beater like a Bamix to create stable foams from skim milk. Simple whisks can do the same for more concentrated non fat proteins like egg whites. But these foams don't pour, instead they have a gel like consistency. Fat prevents the protein from forming a stable foam. So while it's easier to get foam from skim milk, that foam tends to become too stiff and fluffy to be easily pourable. It's easier to get pourable latte art foam from full fat 4% to 6% milk. The fat "destabilizes" the foam and keeps it fluid.

If you are at all interested in the more technical aspects of food, the Harold McGee Food and Cooking book mentioned in the second link is the bible.

Thank you so much guys for your explanations. I think I understand the whole process of pouring latte art better now. I'll put them into pratice cos that's the only way to learn. At least that's what I find with most things. I am getting better with my rosetta, eventhough they are not perfect yet. I'll post some pictures so you guys can tell me my mistakes. Once again, thank you very much guys.