In the last few hundred years there has been rapid advances in science that have revolutionized the way people see and interact with the world around them. These advances have touched almost every aspect of life as we know it- tea is not exempt from such change. Science always prides itself in coming up with ways that make our lives more convenient. It is no wonder then that the biggest changes in the way we prepare tea these days have to do with changes in the most labourous process in its preparation- the boiling of water.
This post looks at the properties of relatively newer materials used to make kettles and the changing heat source used to heat all kettles and tetsubins- modern or traditional. Specifically we will look at how the relationship between water and tea is impacted by the properties of these new materials and how changes to the heat source affects the water used to prepare tea.
Although glass has been used for thousands of years, only recently has it been used as a material for a kettle. This is likely due to the recent advances in science that have made glass relatively more durable and able to withstand higher temperatures as well as making it much more affordable. Glass is extraordinarily neutral in nature. In fact, it is likely the most neutral material ever produced. The neutral nature of glass is a strong quality of the Earth element, of which glass is a part of. It is true that glass is produced from quartz sand, so it is in harmony with the Earth element. Earth is said to control the Water element- glass holds the properties of water constant, protecting it from being degraded but conversely adding nothing beneficial as well. What you put in is what comes out- glass is transparent. Its transparent nature allows for the qi of the water to remain the same as it was before it was placed in.
Because glass is neutral it is a great kettle to use if you wish to enjoy water in its unadulterated form. If you already have very good water you may wish to go this route. Those who boil water in a glass kettle reflect a purity of mind and certain transparency to guests. When we boil water in a glass kettle we can clearly see the progression of the boil from bubbles that are crab's eyes, to shrimp eyes, to fish eyes, to a string of beads, to drumlike waves. A glass kettle allows the tea maker to use sight (inner evaluation) to classify boiling water by these stages. By removing the kettle at a certain stage of boil a certain nature of water is retained- each nature harmonizing best with a certain type of tea. Even though glass is quite a respectable material for a kettle it is rarely used outside of China and Taiwan. Yumcha from The Tea Gallery uses it quite effectively though even if she has admitted to breaking more than one. The lack of durability is glass' downfall.
Stainless steel is probably the most common material used to make kettles these days. It is cheap and durable. Chromium is the major active metal in stainless steel lending it most of its properties. It is chromium that reacts with oxygen making a passive rust proof layer. Therefore this material is resistant to tarnish and rust and is very easy to care for. Being composed of metal it is, of course, connected to the Metal element.
Stainless steel doesn't strengthen, lighten, or sweeten water. In fact it will actually over power and degrade the water boiled in it. It is the case of the Metal element overpowering Water- its properties over take the properties of water. The result is water which has a metallic taste and smell. It should be noted that there are many grades of stainless steel and that better quality stainless steel kettles will have less of an impact on the water but will nevertheless negatively impact the water. Water boiled in stainless steel kettles should therefore never be used to make tea.
Don't think there is much point of mentioning plastic- its materials will leach into the water giving it a plastic taste and smell. Plastic kettles are not healthy and should not be used to make tea.
Once you have selected a kettle or tetsubin the method you use to heat your kettle has a strong influence on the properties of the water and will influence the final infusion. The source that heats the kettle/tetsubin is important as it energetically represents the Fire element in the powerful energetic reaction between Water, the substance of the container (Earth or Metal), and Fire. The four most common sources are discussed below.
Induction heat boils the water when an alternating current is passed through an copper coil located in the base of the heating device. This alternating electric current produces an oscillating magnetic field which leads to an electric current being produced in the kettle resting on top of the heating device. Please see Hobbes' classic article on the details of this heating method here. This method essentially heats the water by way of magnetics. The bonds that hold water together are polar so it is safe to assume that this method may very subtly impact these bonds (or at the very least influencing the minerals that make up the water?), degrading the water's essence.
Induction heaters have many benefits though as they bring water to a strong boil quite fast. A strong, even, quick boil is the ideal when it comes to boiling water for tea. It preserves the essence of the water and creates the most vibrant depth of flavour when making tea. Induction heaters are also quite energy efficient and can be safe in some situations because the actual units emit no heat itself.
The downside of using an induction heater to boil water for tea is that most kettles/ tetsubins including glass, ceramic, iron, and silver are incompatible and are at risk of breakage. Induction heaters also disrupt the tea environment, not only because decent amounts of magnetic energy is sent into the surrounding areas, but also because induction heaters are quite noisy with blowing fans, whining sounds, and electronic beeps taking away from the natural ambiance of the tea session. One need not mention that the magnetic radiation emitted from induction cookers are probably not good for our health.
Hot plates or electric burners boil the water when the electric current in the element encounters resistance which results in heat being given off. The kettle/ tetsubin rests on top and is heated accordingly. The water bonds are not negatively impacted by boiling with a hot plate and the essence of water is retained.
Hot plates and burners are relatively inexpensive and are safe for all types of kettles/ tetsubins. They create some natural ambiance as heat is released into the environment. The downside is that they are not as energy efficient as induction heaters and can get quite hot. They also boil water at a moderate pace. If a hot plate is used to boil water for tea it should be partially heated up first before the kettle is put on so that the water can come to a boil more quickly.
Alcohol burners/stoves such as the ones at Lin's Ceramics (see page 33 & 34 of their catalog) or gas burners/stoves boil the water with a direct flame. The kettle/ tetsubin that is placed over the flame is heated directly. Like the heat from a hot plate, alcohol/ gas heaters do not negatively impact the water.
Alcohol/ gas burners create a very nice natural ambiance as they impart the environment and the water with true Fire. True Fire adds balance of the Elements in a tea space and thereby creates harmony when preparing tea. Problems however are created if the alcohol/ gas burners burn too hot or too weak. If the burners burn too hot they can potentially damage the kettle/ tetsubin. If the burners burn too weak the water will not reach a quick boil and the essence of water will escape leaving you with a flat tasting tea. Most often alcohol stoves are too weak and gas stoves are too strong. You should be aware of the power of this type of heat source and consider the type and quality of your kettle and tetsubin carefully before use.
Hardwood charcoal boils water as the glowing embers release infrared thermal radiation due to the powerful release of energy in the dense hardwood. This radiation heats the kettle/tetsubin and the water inside. The heat from hardwood charcoal is penetrating and deep and boils the water in such a way that shortens the water bonds and alkalizes the water (see Steve Owyoung's comment here). In this way water can be enhanced by use of hardwood charcoal.
Boiling water with hardwood charcoal connects us to nature and slows our minds down (see this article in The Leaf). The ambiance created by the true Fire of hardwood charcoal is unmatched as it also deeply penetrates our body and mind. If done properly, it will boil water quickly, deeply, and evenly and will bring about a more vibrant, deeper tasting tea. Tending the charcoals is truly an art in and of itself and is often considered the most important aspect of preparing tea.
Using hardwood charcoal is very time consuming, expensive, and can be messy but it is very rewarding. If you use hardwood charcoal it is important that you get high quality charcoal that is odorless, smokeless, and burns clean less you be smoked out. Always remember to crack the window as well to vent the small levels of carbon gas that can build up with continued burning. You also must make sure that your kettle can withstand the heat given off from hardwood charcoal. Silver kettles and some ceramic or gas kettles may not withstand the heat.
Many thanks for this complet article.
Great info, thanks Matt.
I am in the process of ordering a Lin's stove for my actual kettle but also for a future glass one. I wonder though about the fragility of such a kettle...
A glass kettle should have no problem with Lin's alcohol stove- but this comment is not coming from experience with this exact kettle/burner. Guess you'll just have to feel things out for yourself or maybe contact the dealer?
Thanks for your interest and ongoing participation in this series.
Many people prefer the cordless as it is easy to pour the tea without having the restriction of a cord determining your distance of movement. The corded tea kettle comes with a cord that plugs directly into the wall.
You are right that there is a certain convenience about a cordless electric kettle...
(This may very well be the most relevant spam comment ever posted... Hahaha)
"Stainless steel ... will actually over power and degrade the water boiled in it."
I did a comparison between water boiled in clay kettle versus boiled in a stainless steel kettle. While thethere was a clear difference - clay kettle water seemed softer and going down more naturally, stainless steel water tending to stay more in the front of the mouth - I did not detect any metallic taste or smell to the stainless steel water.
"clay kettle water seemed softer and going down more naturally, stainless steel water tending to stay more in the front of the mouth"
One has also found similar results when comparing clay with stainless steel.
"I did not detect any metallic taste or smell to the stainless steel water."
The metallic taste of stainless steel is a certain thing with new stainless steel kettles. The affect on taste and smell seems less and less a factor with use to the point where you can no longer detect it especially in higher grade stainless steel.
Thanks for sharing your experiences with these two kettles, much appreciated.
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