Let me start with my definition…
Black and Tan: A Black & Tan is a beer made by the coupling of a pale ale (or bitter, or mild) with a dark beer such as a stout or porter.
After that, it gets a little more complicated because there is no one, official, black and tan.
I use the word “coupling” in my definition because (most commonly) the trick here is specifically not to blend the two beers, rather, to have the darker beer sit on top of the other beer in the glass. However, some people believe, and prefer, their black and tans to be mixed thoroughly by pouring the pale ale first. Saranac and Yuengling make a pre-mixed, bottled, black and tan.
Why does this separation of beers work? Actually, people still argue over why, but the primary reason it works is that one beer is actually lighter than the other. If the beer is carbonated with nitrogen (nitronated) it will be lighter than a beer carbonated with carbon dioxide because nitrogen is a lighter gas.
Note: The fact that N2 gas bubbles are smaller than CO2 bubbles, and that many stouts like Guinness are thicker from proteins which come from the ingredients and brewing process, doesn’t necessarily apply here. However, it may have something to do with preventing the two beers from mixing , or breaking through the layer of the other beer, during a pour. So, some people will argue that viscosity is a factor.
(Ron thinking to himself — so, this principle should apply to any nitronated beer like Boddington’s Pub Ale. … you could put a carbonated porter on the bottom and a nitronated one on top… I guess I have some experimenting to do… sorry about thinking out loud … you don’t want to get caught up in my brain)
Most commonly, and some will tell you traditionally, Guinness Stout and Bass Pale Ale are the beers that make up a black and tan. The reason most think this way is because that is how Guinness has promoted their black and tan. Others will claim that it is better if it is all Irish and use Harp instead of Bass, but reality is that the Irish rarely have heard of the drink. Truth be known, Guinness Imports Ltd. also imports Bass Ale… now you understand.
Another variation to the black and tan is its name, referring to it as a “Half and Half”.
So there you have it – it’s now clear as mud. But, how does it taste? It’s great, actually. I like it both ways, separated, or mixed. Having it separated is not just pretty cool, but as you drink it, there is a smooth transition from one to the other and it is quite unique and enjoyable.