Hello!

Here we are, a few days ago I woke up and found myself in front of a strange device, quite common here in Italy. What's that? Well, it's a coffee maker, for those who have never seen one, that is, a device that allows you to prepare an excellent coffee; a coffee that will be a little less excellent depending on the type of coffee or one's knowledge in the preparation phases: mine is the minimum essentials, certainly not at the level of excellent coffees. But let's see it better.

I saw different types of coffee makers in Italy, these are one of the most classic and ancient forms for domestic use, today increasingly replaced by semi-automatic or even automatic machines. The coffee maker in question is branded Tognana, but I removed the brand from the image to avoid possible direct advertising. The macroscopic pieces from which it is made up are 3: a base, an intermediate filter, and an upper part. Here are the 3 components in the figure, separated from each other.

This type of coffee maker is what is defined as MOKA, from an invention by Alfonso Bialetti which - the web teaches me - seems to date back to 1933.

The components

The base, also called WATER CONTAINER, is that part that will rest on the heat source and that will contain a predetermined quantity of water. We will have to maintain a limited level of liquid, which varies according to the capacity and shape of the filter that will be inserted.
The FILTER FUNNEL is that part (perforated at the top and with a funnel shape at the bottom) that will be inserted inside the base and which must be filled with ground coffee.
The upper part, also called COFFEE CONTAINER, will be left empty, and it is the one that will be filled with liquid coffee: this is possible thanks to a duct that allows the freshly brewed coffee to rise from the base to the upper container. The duct is called COFFEE PIPE.

First, I would like to point out that "coffee" is a term popularly used to indicate both coffee powder (ground coffee) and coffee-flavored drink ("Can you prepare me a coffee?").

How do you use a MOKA coffee maker?

I will not reveal the secret of the Neapolitan guru who grew up in the Bialetti factory and with a centuries-old tradition in ground coffees because I don't know either. What I am showing you is a quick and easy approach to everyday use. Then there are various philosophies for the preparation of coffee that an expert can certainly submit to you to improve the final result. But let's get down to work. Let's imagine that it is you and me, in front of a stove and the three separate parts of our coffee pot.

First, we take the base, the water container. It fills with water up to the step which should be visible inside. Possibly, it would be better to leave an empty space between the surface of the water and this step, as the filter could take up more space due to its shape.

A tip: to be sure of an adequate level, it is useful to insert the part indicated as a filter inside the base after having filled it with water. The filter is inserted keeping its vertical duct facing downwards. At this point, if you see water appear inside the filter, you will know that there is too much water. You will have to remove it until, by carrying out this check operation, you will no longer see the water appear inside the filter.

Well, the second step: let's fill the filter.
Once the filter has been inserted with the vertical barrel facing downwards, make sure that it adheres perfectly to the water container. At this point, we take the coffee powder and begin to fill the empty part of the filter with a small pile. Here are some philosophies: personally, I don't make the coffee and leave this "hill" shape, with the edges of the ground coffee heap touching just below the top of the side edge of the filter. Excessive compression can create safety problems, especially if the coffee makers are outdated.

Finally, we take the top - the collector - and screw it onto the base (which has the filter with the coffee stuck inside). Once tight, we got our coffee maker whipped. Finally, place it on the stove before starting the heat source.

Once turned on, we will have to wait for the coffee to be ready. But WHEN will it be ready? Let's see the technical operation described in a simple way to understand when we have reached the right point.

How does a MOKA work?

I admit that the classic and most banal mental representation is that water is heated; begins to evaporate, rises through the filter being enriched with coffee, and continues through a second filter that leads the steam to the collector, where it becomes liquid and collects. Well, this simpler representation would seem wrong.

Another short web search gave me the most correct and accepted representation. It is a fairly simple but quite effective physical system. Let's see it.

Placing the coffee pot on a heat source, the heat causes the water in the container* to start boiling. By boiling, the water changes to a gaseous state, a state in which the molecules take up more space than the liquid state. This causes a pressure increasing in the container, as the gas remains trapped inside it and begins to press towards the bottom (point 1 of the image below). A safety valve is usually positioned alongside in order to avoid dangerous situations due to obstructions of the ducts and/or excessive pressures. When the pressure increases, the water at the bottom finds the vertical filter duct completely empty, and begins to rise from there (point 2 of the image below). At that point, the water reaches the ground coffee and is enriched with the aromas of the coffee powder (point 3 of the image below). It then continues upwards through the coffee pipe, that duct with which the coffee container is equipped (point 4 of the image below). On the top of the pipe, small holes allow the liquid coffee to come out of the duct and fall back into the bottom of the coffee container (point 5 of the image below).
When the water level in the water container has dropped enough, the water will no longer be able to rise and the liquid coffee will stop flowing out of the coffee pipe.

This is how it works. But we, I say, how do we understand the precise moment when the coffee is ready? As for these simple coffee makers I use, we will hear a gurgling noise, a boil activity emitted by the coffee maker: it is the moment when the coffee starts to come out of the coffee pipe. When it stops coming out, the boil is extinguished. Having said that, it would be good to remove the coffee maker from the heat source BEFORE the boil ends, avoiding unpleasant burning notes that sometimes there may be. In addition, it is advisable to mix the drink inside the coffee pot with a teaspoon. This is for two reasons: the first coffee that comes out of the pipe will be more concentrated and could also have an extra burnt note due to its proximity to the red-hot bottom of the coffee container.

That's it, it seems to me that everything is there. I think I will prepare a coffee soon. I hope I have given you enough overview to give you an idea of how to approach a coffee maker. Who knows, maybe you have never tried it, and you bought one of it due to a curiosity moment, or maybe you found it among the crockery of the apartment borrowed for a holiday. It isn't so important, much more important is that you have managed to find some useful ideas for the first approach.

A greeting and see you next time!