Shaving foam vs Sea foam: shaving foam is loaded with المواد الخافضة للتوتر السطحي and is therefore extremely stable compared to seafoam.
There are lots of different kinds of foam. Shaving foam for example is made up of ultimately small bubbles that are virtually impossible to burst unless you dilute them down with a lot of water. Compare this to bubbles created by a waterfall, or sea foam created by a wave breaking on the shoreline. Have you noticed that seafoam breaks up almost the instant it is created? This is because saltwater doesn’t contain enough surfactants to hold the bubbles together. Surfactants are surface active agents that lower the surface tension of a liquid and have the ability to wrap around air bubbles, hold them together and make the films of each bubble more elastic, which makes them harder to burst. Dishwashing liquid, for example, is a المواد الخافضة للتوتر السطحي — it lowers the surface tension of water and makes for a long lasting foam.
When steaming cow’s milk, the success of your foam creation hinges on the milk’s protein content. Cow’s milk has two main proteins: casein and whey. Casein accounts for 82% of milk’s protein, providing vital amino acids and forming micelles that contribute to milk’s white colour and nutritional benefits. The remaining 18% is whey protein, and β-lactoglobulin, a key component of whey, serves as the main المواد الخافضة للتوتر السطحي in milk and gives a milk foam its elasticity and longevity.
Understanding التصريف
The glasses to the right of this image have undergone more التصريف than those on the left side
التصريف is the process of a liquid percolating through a layer of foam. التصريف rates are faster when foams are made of bubbles with larger diameters.
Have you ever heard of the terms ‘wet foam’ and ‘dry foam’? A dry foam has very little liquid between the bubbles. Take the beverage GuinnessTM for example. When a bartender first pours a pint of Guinness,