I tried making koicha with different amounts of water.

My dilemma on making koicha, thick tea
The distinction on the way of making koicha is that you add water twice. A typical instruction is something like this;

Put three scoops of matcha into the bowl and add a little amount water.

Blend them by moving the whisk slowly to a make smooth paste of tea

Add appropriate doses of water and mix it well with whisk.

Koicha, thick tea

This is what I learned at my tea school and you will also find a similar instruction on many books. I think that it is very ambiguous for first-time learners. I'm still not sure how much the appropriate doses are. I wish if there was guide on how many grams of tea and how much milliliter of water should be used.


Informations that I collected from books
Not many books explain the way of preparing koicha with specific amounts. However, I found some informations in some books and I'll introduce them here;
Amount of tea
- 3.75g (Sen Soshitsu XV)
- 3.4g (Note on the instruction manual for a tea sifter)
Amount of water
- The same as usucha, thin tea, Three-and-a-half swallows (Sen Soshitsu XV, Tankosha)
- First water: 25ml (Tankosha)
- First water should be 30-40% of entire water. The amount of water should be enough to get the tea powder to float slightly. (Horiuchi Soshin)
Each author or publisher has their own way and there is no coherence among the above-mentioned information.


Weird result
To study for myself, I tried making koicha with different amount of water. I used 3.6g of matcha on each brewing.
 60ml - Too thin
 40ml - Too thin
 35ml - Good thickness
 38ml - Good thickness (slightly thin)
I didn't find a big difference in thickness between the 60 and 40 tea even though there was certain difference on the amount of water (20ml). On the other hand, the 38ml tea had a quite good thickness compared to the 40ml tea. Only 2ml made a big difference. I was very curious how it happened. In the beginning, I wanted to know the best amount allocation on the first and second water. I made some adjustments on each brewing in the amount of the first water. Maybe, the way of how I moved the whisk was not consistent either. These caused the weird result. The thickness can be affected by how you move the whisk and the proportion of the first and second water. I actually experienced and learned it.


Ten times of water
I will skirt around the issue of the water allocation and the way of whisking this time. I'm going to focus only on the entire amount of water. From the previous experiment, I made an educated guess that my ideal amount of water will be about 10 times of tea. I fixed the amounts of the first water at 18ml and the tea at 3.6g, and did the test again. I tried three different amounts;

My assumption was quite correct! I was satisfied with the thickness of all the three teas. The 9-time tea had good thickness and it still runs smoothly. The 11-time tea was light but I could still enjoy the significance of koicha. To conclude, I can say that my guide is about 10 times the amount of water against the tea.


Numbers are useless
You need to adjust the amounts depending on seasons and guests. Also, the numbers are useless once you are in the tea room. I think that is why there is no specified amount of ingredients on books or taught at schools. I believe that you have to learn it on your own by carefully watching the amount of tea on your scoop and the water poured into the bowl.