How can I layer liquors on top of each other?
The key to creating perfectly layered drinks is to pay attention to how heavy each ingredient is compared to the other ingredients. The weight of each liquid is measured by its specific gravity.
An alcohol density chart can be viewed here.
There are a few simple rules to follow:
You want to use a ...
Does this count?
12-Layer Pousse Café
creme de cassis
green creme de menthe
MxMo: Pousse Café
Here is a seven-layered Pousse Café:
1/4 shot ...
The most layers I have seen (and drunk) is the Pousse Cafe No. 1 - with 6 layers.
It has equal measures of 6 liqueurs and spirits:
Creme De Menthe
Creme De Violette
Pouring uses the usual layer process - pour down the back of a spoon...very gently, so you don't mix with the previous layer.
Pic from epicurious....
It does depend on the liquor you're using since they have specific gravity's. You can pour them carefully over a spoon to minimize disturbance, or (what I always did) pour them slowly down the side of the glass, one by one in order (highest gravity on bottom).
This page spells it out pretty well: Specific Gravity Chart for Layering Drinks and Shots.