1. What Is the Tea Strainer Inside a Teapot?
Open the lid of a teapot at home. Look at the base of the spout. You may see many small holes or a metal mesh attached there. This is the tea strainer. [1]
When brewing Japanese tea without tea bags, the tea leaves are often very fine. Without a strainer, the leaves would flow into the cup along with the hot water. Wikipedia explains that the strainer exists to prevent this. [1]
But this raises a question: Was the teapot originally made only for brewing tea? The clue lies in the teapot's past shape. The next section looks at what the teapot was first used for.
2. How the Teapot Began as a Vessel for Boiling Water
Some sources state that the teapot was originally used for boiling water or warming sake, and only later became used for tea. In Japan, this vessel was historically called the "kibisho." [1]
In the mid-18th century, during the Hōreki era, a person named Ko Fuyo noticed the potential of the kibisho, which had originally been a water-boiling vessel. This observation was recorded in a book called "Kanjado Zatsuroku." It is thought that teapots specifically for tea began to be made in the Kansai region around this time. [1]
Another source traces the origin of the teapot to southern China during the Tang and Song dynasties, where tools were used to warm wine or water. These were introduced to Japan via Nagasaki during the Edo period. The shape with a handle on the side is said to have developed in Japan to make it easy to pour while sitting on tatami mats. [2]
If the vessel was for warming water, the contents were water or sake. A mechanism to strain tea leaves was not necessarily needed from the start. The strainer may have become an important part only after the vessel was used for tea. The sources used here do not state exactly when the strainer was added.
3. How Teapot Strainers Changed from Ceramic Holes to Stainless Steel Mesh
From the Edo period through the Showa era, the mainstream tea strainer in teapots was an "integrated" type with holes made directly in the ceramic body. Wikipedia explains that this was not a separate part attached later, but holes made in the clay before firing. [1]
Even today, Tokoname teapots (from Aichi Prefecture) feature a style called "dodake," where holes are made directly in the body. It is said that this does not hinder the convection of the water, allowing tea leaves to open slowly and bringing out umami. However, this difference in taste is presented as an explanation, not a proven fact. [6]
After World War II, teapots with stainless steel strainers that are less likely to clog became widespread. Wikipedia notes that the background for this change was "changes in tea manufacturing methods." The sources do not specify exactly how the methods changed. [1]
So, what does "clogging" mean for a strainer? And what happens when tea leaves are fine?
4. Why Deep-Steamed Tea's Fine Leaves Need a Particular Mesh Size
According to the Ministry of Agriculture, Forestry and Fisheries, the standard steeping time for sencha is about 1 minute and 30 seconds. For deep-steamed sencha, the leaves are crushed finely during processing, so the steeping time is shortened to about 30 seconds. This is because the components come out faster due to the finer leaves. [3]
Deep-steamed tea is sometimes introduced as tea steamed for more than twice the usual time. However, this is an introduction from a TV program and is not a number defined by the government. [4]
In 1981, a personal utility model patent was filed. This document lists problems with traditional strainers: the holes were too large, allowing many fine tea leaves into the mouth, causing discomfort. It also noted that some strainers could not be removed or were difficult to attach and detach. The goal was to create a fine-mesh strainer that blocks small leaves and can be easily attached and detached. [5]
This is one person's invention idea, not the sole reason stainless steel mesh became widespread. Still, it clearly describes the relationship between fine leaves and mesh size.
5. How Band Strainers Filter Tea Through the Sides Too
Tea strainers come in various types besides the ceramic "integrated strainer." These include circle mesh, basket mesh, round mesh, flat mesh, pock mesh, and band mesh. The names suggest that strainers come in many shapes. [1]
A band strainer is a mesh shaped like a band that goes all the way around the inside of the teapot. Because it filters through the sides as well as the base of the spout, the area through which water passes is wider. [1]
A wider area seems less likely to clog, but this is the author's view based on the structure, not a stated fact from the sources.
6. Why You Should Pour Tea Until the Last Drop
The Ministry of Agriculture, Forestry and Fisheries states that if water remains in the teapot, components continue to leach out from the leaves even while waiting to brew the second cup. Therefore, it advises pouring out the "last drop." [3]
When there are multiple cups, the guide suggests not filling one cup at a time. Instead, pour a little into each cup in order, then go back and pour again. This method, called "mawashi-jogi" (rotating pour), ensures the strength of the tea is the same in every cup. [3]
When you tilt the teapot significantly to pour the last drop, the tea leaves inside flow toward the spout. Here, the strainer may help keep leaves out of the cup. This connection between the strainer's role and the instruction to pour completely is an interpretation linking the two descriptions, not a direct statement from the sources.
7. How to Check the Strainer in Your Own Teapot
If you have a teapot at home, ask an adult before looking inside before adding hot water. Is the strainer holes in the ceramic or a metal mesh? Is it only at the base of the spout, or does it extend to the sides like a band strainer? Look closely at the holes or mesh without touching them to compare how fine they are.
After that, brew one cup with your usual tea leaves and pour until the last drop. Check if any leaves enter the cup and what leaves remain in the strainer. If you compare different tea leaves, keep the amount of leaves, water volume, steeping time, and pouring method the same. Be careful of burns and handle hot water with an adult.
A guide for caring for Tokoname teapots explains that dirt and powder accumulated at the base of the spout should be washed with a brush and dried thoroughly overnight. Use a soft brush to avoid damaging the holes or mesh. [7]
For brewing methods by tea type, the Ministry of Agriculture, Forestry and Fisheries provides tables and numbers in their materials. [3]