What is Gansai?
You have probably heard of the big brands like Kuretake Gansai Tambi, or Kisshou Gansai, but what is gansai really?
Gansai (顔彩) is traditional Japanese watercolor. In English, we tend to refer to both types of paints as simply watercolor. However there are two words for these types of paints in Japanese. Gansai is written 顔彩 and the type of water colors that are more traditional in the West (also called transparent watercolors) are written 水彩.
While Western watercolor is traditionally bound with gum arabic, gansai is bound with a combination that could include glue, starch, gum arabic ,beeswax, sugar syrup, sugar, or glycerin . The glue is made from concentrated collagen and gelatin that has been extracted from animal and fish skins through boiling   . When the pigment and binder is mixed together, they are dried in pans. Those in large square pans are called gansai 顔彩, and those in round dishes are called teppatsu 鉄鉢 . They can also be formed into a sort of watercolor pastel/crayon that is called bouenogu 棒絵具 
What is it used for?
More Convenient Version of Iwaenogu 岩絵具 or Suiengou 水干絵具
Iwaenogu 岩絵具 is a type of traditional Japanese paint which is generally made from semi precious stone and other pigments (such as Cinnabar, malachite, azurite, lapis lazuli, etc.) that have been crushed and mixed with the same type of glue that is used in gansai by hand right before it is used. They are very expensive and available in a range of particle sizes.
Gansai is not made with the same type of very expensive pigments used in iwaenogu. Generally, gansai uses the same pigments as suiengou 水干絵具 . Suiengou is made from fine pigments or dyes combined with chalk made from shellfish  or purified clay . The pigments are also a bit cheaper than iwaenogu even though they are still of high quality and very lightfast. Just like iwaenogu, suienogu is sold in pigment form and must have glue added to it just before painting.
Since gansai has already been mixed at the proper ratio and is already dried in a pan or dish, it is much more convenient to use than iwaenogu. It’s like the difference between using Western pre-made pan paints versus making your paint by yourself each time you are going to paint a picture.
Underpainting for Iwaenogu 岩絵具
Both suiengou and gansai are often used as the underpainting for iwaenogu because they are much cheaper than the expensive pigments used in that type of paint. By painting with one of these two, the artist can cover up the white of the paper or cloth and provide a ground for the Iwaengou to stick to .
Sketching and Etegami 
Because it is not as expensive or difficult to use as iwaenogu or suienogu, gansai is often recommended for sketching. Iwaenogu and suienogu are not as convenient as gansai, since they come in pigment form and must be combined with a binder right before painting. On the other hand, gansai is already premixed and in a container, so they are ready to go whenever the feeling to paint strikes you. That makes them a perfect sketching medium.
These are also the reasons that make them great for etegami or Japanese picture postcards. Etegami are meant to be fast, casual, and imperfect. They are full of simple, bright colors and drawings that are meant to express emotion more than accuracy. So this quick medium is also suited to these types of drawings.
Vibrancy and Opacity
When gansai is watered down it retains its vibrancy more than Western watercolors do. Also,gansai’s binder can give it a shiny finish.
Gansai tend to be more opaque than transparent watercolors. Remember that these paints were formulated to work on Japanese paper. Transparent watercolors do not show up very well on Japanese paper, and the additional opacity of gansai help them to appear on the paper with little bleeding.
The binder adhesion in gansai is weak compared to other Japanese paints. As a result, they tend to lift much easier than most transparent watercolors, even when dry.
There are a few things that could contribute to this. When gansai is used on Japanese washi paper, it doesn’t lift as easily as it does on Western watercolor paper, especially when used with ultrasoft Japanese goat-hair brushes. Traditional Japanese paintings are and also not as dependent on layering as Western watercolor paintings, so there is less opportunity for the paint to lift when new layers are added.
The colors of traditional Japanese gansai sets are often different from those in transparent watercolors. These paints were created for Japanese picture painting, which comes from a different tradition than European painting. Japanese colors are also based on colors that can actually be seen in nature, which would probably explain the abundance of blues and greens in many gansai palettes.
The colors can give a calm and peaceful feeling to the viewer because they are not overly saturated.
Why are gansai pans so big? Japanese brushes can be much bigger than Western-style brushes, so they need a bigger pan to ensure the brush hairs are not damaged.
Gansai were not made to be mixed in the same way that transparent watercolors are. This is part of the reason that many gansai sets do not come with a mixing palette.
I have read many reviews that say that gansai paints get muddy when mixed, this makes sense considering the traditional background of the paints, however I have never experienced this. The colors I have been able to mix from gansai have been very clear and bright.
Many reviews disparage the quality of gansai because they don’t act in the same way that Western watercolors do. I think that this is unfair. They are not the same type of paint, so they can’t be expected to behave in the same way.
Of course, just like there are high-grade and low-grade watercolors, or high-grade and low-grade oil paints, there are high-grade and low-grade gansai paints.
Western Paints (eg: Winsor and Newton, Schmincke) versus Gansai
|Come in half and full pans||Generally come in one size pan|
|Gum Arabic binder||Binder may be a combination of glue, starch, gum arabic ,beeswax, sugar syrup, sugar, and glycerin|
|Tend to be more transparent||Can be more opaque|
|High quality versions mix well||Can be more difficult to mix 3 or more colors|
|Varying staining levels||Mostly lifts very easily|
|Dries Matte||Dries Glossy|
|Available in Tubes||Not available in tubes|
- 水彩と顔彩 | 集積—イメージ・ことば
- 顔彩・鉄鉢 | 日本画材料 吉祥
- 塗り絵 | 日本画材料 吉祥
- 初塗り ～顔彩でチューリップを描く～｜卓上工房の奇人 細密水彩絵師・柴猫由貴の奇行録
- 吉祥顔彩の使い方 - YouTube
- 金色ノ鮒 [konjiki no funa] 2: 顔彩と水彩
- 水彩絵の具と絵の比較♪ - ゆりYO船長 お魚love♡ | クックパッドブログ
- トランスミッター | エムブロ！
- 顔彩の使い方 - YouTube
About Traditional Japanese Painting in General
- Paint for Japanese paintings
- 絵を描く.com - 日本画を描く 紫陽花を描く
- Japanese painting paint - Japan paint | Musashino Art file
- 分類からさがす | 武蔵野美術大学 造形ファイル
About Japanese Colors
Blue and Green
- word choice - How indistinguishable is blue from green really? - Japanese Language Stack Exchange
- Is this green or blue in Japanese? | IroMegane
- Blue–green distinction in language - Wikipedia, the free encyclopedia
- Ao (color) - Wikipedia, the free encyclopedia
- The Japanese traffic light blues: Stop on red, go on what? | The Japan Times
- The crayola-fication of the world: How we gave colors names, and it messed with our brains (part I) | Empirical Zeal
- Traditional colors of Japan - Wikipedia, the free encyclopedia