Tips for Foamier Drinks
When you need to give your drink a foamy top, dry shaking and reverse dry shaking are great methods to use. What if you want to do something different or you want to try making the foamiest drink ever seen?
The key is to remember what causes foam in the first place: denaturing the protein so that air can become trapped. You can beat it, you can heat it, and you can chemistry it. With mixed drinks, heating it will only work for a drink served hot. In this article, we are going to ignore hot drinks, so heat as a denaturer is also going to be ignored. We’ll focus on beating, or mechanical force, and chemistry.
It’s all chemistry, actually, but let’s not geek out too much.
The basic foam creators
With all the tips below, I would be remiss not to ensure we start with a good foundation: Dry Shaking and Reverse Dry Shaking - just in case you got so excited and forgot about them. These two techniques are easy and likely require nothing new - just for you to change your process.
Dry shake
Shake your drink but exclude the ice. Then shake for another 12-15 seconds with ice, strain, and serve.
Reverse dry shake
Combine ingredients except for the foaming agent, add ice, and shake for 12-15 seconds. Then strain into another mixing tin. Add the foaming agent to your ingredients and shake for another 12-15 seconds, then pour into your service vessel and serve.
Try these
Mechanical force
Hawthorne strainer spring
Remove the spring from your 
Wire spheres
The problem with using a spring from your strainer is that your strainer is unusable until you fish the spring out and put it back together. Instead of using the spring you can use 
Larger ice
Shake with a large ice cube. You’ll want to include a few small cubes, since the large cube won’t dilute your drink as fast. This ice mold tray will help you make those 
A block
If you don’t want to use up your large cubes, then put a large block in your shaker instead. What should that block be made of? It doesn’t have to be ice. The ice isn’t what causes the
increase of foam - it is the shape, or specifically, the shape of something slamming air into your liquid. I enjoy using the 
A drink mixer
A tiki trick is to use a drink mixer. These aren’t blenders, with the blades at the bottom of a pitcher. These are your milkshake machines, with long spindles that extend down into your tin. Only use a
metal mixing vessel with these to avoid glass shards in your drink. The 
Chemistry
Use Metal
One thing I learned from Harry McGee’s 
Carbonation
Add a little bubbly water to your shaker - a trick often used in fizzes. As the carbonated liquid’s nucleation sites interact with the other ingredients, the CO2 will be released. Shaking makes those interactions happen very quickly. CO2, as a gas, will become trapped in the foam’s protein structure. On the positive side, it is like pumping air into your foam. On the negative side, and be forewarned, this will cause the pressure to build up quickly in your shaker. Make sure you have a very tight seal and shake with two hands, or else things will get messy.
Stabilizing agents
Egg whites and cream are stabilizing agents, which will keep your foam from collapsing. Your recipe might allow you to use more of a stabilizing agent, or you can add agar, lecithin, gelatin, or xanthan gum.
More protein
A foam is a matrix of proteins which have been denatured and coagulated together, capturing air and water within the framework. Add some more protein and you can create more of a framework. An easy way to do this without dumping protein powder into your drink is to adjust what type of milk or dairy you are using.
Freshness
When it comes to dairy products and eggs, fresh is better for foam. Dairy products that are stored undergo lipolysis. This is when enzymes and bacteria break down the dairy product, producing monoglycerides and diglycerides - both of which decrease foam production and stability.
No ice
This will work if your drink is pre-diluted and pre-chilled. As you shake your drink with ice to create a foam, that ice melts and dilutes. While an egg white starts off as 90% water and 10% protein, the added water increases the water to protein ratio. This makes it more difficult to create the foam matrix. So remove the ice from the equation in an effort to not over dilute your drink.
Avoid these
Whisk foam then shake
You risk over whipping and breaking your foam.
Whisk then put on top
You can do this, but the foam will not have captured any of the aromatics from the drink ingredients.
Boston shaker
Glass is not as beneficial of a material as metal when creating foams. Therefore, make a foam in a tin-on-ton shaker or a metal cobbler.
Plastic shaker
Allegedly, since plastic is a softer material it is more likely to be contaminated with oils and fats from an inadequate cleaning job. Oils and fats can inhibit the creation of a proper foam.
More ice
Adding more ice might increase the surface area that beats against the proteins you want to denature, but it will also cause excessive dilution and prevent a proper foam from forming.
Over shaking
Why not go ahead and shake the heck out of the thing? A 10 minute dry shake should give you a 8” foam that’ll never collapse, right? I haven’t actually tried this, but foams can be overwhipped. When whipping a foam outside of a mixed drink or cocktail, when this happens, your foam matrix can become so dense that it squeezes out the water within the foam, leaving a puddle under the foam and giving you a slightly gritty texture.