A French press coffee mug is a portable, or travel, coffee mug that has a built-in French press mechanism so coffee can be made right in the mug. The term "French press" generally encompasses both the French press device and the method by which one prepares coffee with the device. Usually, coffee is prepared in a coffee pot and poured into a mug. In a French press coffee mug, though, the coffee is prepared right in the mug, so the separate coffee mug is not necessary. A French press coffee mug can only be used to make one mug full of coffee at a time, however.
The French press coffee preparation mechanism is made up of a vessel for holding the water and coffee and a plunger device with a porous filter end. Hot water and coffee grounds are poured into the vessel and left to steep for a few minutes based on how strong one wants the coffee to be. After this, the plunger, often attached to the top of the French press coffee mug, is inserted into the vessel. The plunger is pressed down to the bottom of the mug, trapping the coffee grounds at the bottom and leaving the vessel full of coffee. The plunger is porous so the coffee can flow through it, but the coffee grounds cannot.
While the preparation method is the same, some differences do exist between a French press coffee mug and a French press coffee pot. In general, a French press coffee mug will be made from metal or plastic while the coffee pots are often made of glass. In most cases, the mugs also have lids that can be tightly sealed as well as small, holes through which one can drink. All of these features minimize the risk of spilling coffee or breaking the mug while carrying it around.
The French press coffee mug is popular because the preparation method is simple and many people feel that it produces very good coffee. Preparing the coffee in the same vessel that one will later drink from results in greater mobility and less cleaning as well. As in any preparation method, however, the goodness of the coffee depends on a variety of factors, including the quality of coffee beans used and the care put into preparation. Low-quality beans will lead to low-quality coffee. Additionally, if the coffee grounds sit for too long in the water, the coffee may become too strong and bitter for one's taste.