Drinking Tea is not just about quenching thirst, tea enthusiasts have high standards for both tea leaves and tea wares. The water should ideally be from a mountain spring, the tea leaves should be the tips, and as for the Kettle, it's best if it's an old iron kettle. Thus, there are no shortages of news stories about people paying large sums to acquire old iron kettles. Besides their value for collectors, old iron kettles are also said to offer health benefits. It's rumored that an old iron kettle has superior heat retention compared to other kettles, which can increase water temperature, soften the water quality, and release divalent iron ions. The water, originally ordinary, becomes healthy and rich in iron ions with these additional iron ions. Moreover, the divalent iron released when the iron kettle heats up can interact with the tea, supplementing iron to the human body.
But does the old iron kettle really have such miraculous effects?
First, let's discuss whether an old iron kettle can raise the water temperature. The boiling point of water is generally 100 degrees Celsius, which can vary slightly depending on atmospheric pressure at different locations. However, whether water boils or not is only related to atmospheric pressure and has nothing to do with the container used to heat it. There is another theory that when there are many dissolved substances in the water, the boiling point of this water will rise due to the different boiling points of the dissolved substances. Even though an old iron kettle can dissolve a negligible amount of iron into the water, this tiny amount of iron cannot affect the boiling point of the water. Therefore, an old iron kettle cannot increase the temperature of the tea.
Next, let's talk about the heat retention ability of an old iron kettle. A container's heat retention depends on the thermal conductivity of its material and the thickness of the container. Iron has excellent thermal conductivity, meaning that more heat is wasted when using an iron kettle compared to glass or ceramic kettles. People often believe that iron kettles have good heat retention because they can warm up the Teapot more quickly, leading them to think that iron kettles can retain heat better. This is actually due to the better thermal conductivity of iron, which allows heat to spread quickly throughout the iron kettle and begin transferring to the surrounding air. After the heat source is turned off, the accumulated heat in the iron kettle is also transferred to the air more rapidly.
Can an iron kettle soften the water and give you the feeling of mountain spring water? The hardness or softness of water is not determined by iron content but by calcium and magnesium ions. Generally, to soften water, the calcium and magnesium ions are removed. When water is heated in an iron kettle, even if a certain amount of iron ions are released, the amount of calcium and magnesium ions does not decrease, so the water cannot be softened.
At least, can an iron kettle provide iron supplementation when heating water? Indeed, a significant portion of adults suffer from iron deficiency and need iron supplementation. According to legend, an iron kettle can release a large amount of divalent iron after heating. However, even if this were true, brewing tea in an iron kettle could not provide iron supplementation to humans. Firstly, the amount of iron released during the heating of water in an iron kettle is very limited. Secondly, the divalent iron that is released reacts with compounds like polyphenols in the tea to form a complex compound, where the divalent iron is oxidized into trivalent iron. As a result, trivalent iron cannot be absorbed by the human body, and the desire for iron supplementation is unfulfilled. Additionally, the polyphenols in the tea are also bound, diminishing the benefits of Drinking Tea.
Therefore, relying on an old iron kettle for heat retention, iron supplementation, or transforming water into mountain spring water is not advisable. Paying a high price or bidding for an old iron kettle for these reasons is not worth it. Of course, if you view an old iron kettle as an art piece, antique, or purely for collection, that's a different story.