The Kahva coffee maker is made of glass and metal

The Kahva coffee maker designed by Lina Fischer is made of glass and metal and looks like an hourglass. His whole coffee-making process is magical. First of all, pull out the inner core and add the right amount of water to the glass pot, and then insert the inner core of the coffee powder. Plug in the electricity and the water in the kettle gradually boils. You will find that the water level keeps falling until most of the water has disappeared, and then wait patiently for a while, and you will find that the water has become brewed coffee and gradually increases again. Now you can pour out the coffee and enjoy it.

Have you figured it out? In fact, the principle is very simple. The weight of the inner core and the sealing strip above it completely insulate the air outside the conical tube in the lower part of the hourglass from the outside world, and a small part of the water surface is connected to the atmosphere through the conical tube. When the water is heated to boiling, a large amount of water vapor is produced, increasing the pressure in the closed cavity and causing the water level to rise continuously. The pressed boiled water dissolves with the coffee powder and becomes fresh coffee. As the temperature drops, the water vapor in the closed cavity gradually changes back to water, causing the pressure in the cavity to return to normal, and the coffee flows back to the lower half of the hourglass.

The amount of "sand" from the hourglass is an indication of how long the coffee has been brewed, and you can tell whether the coffee has reached your accustomed temperature by the height of the water surface. I have to say what a perfect design it is!