This section presents the results of interviews conducted on traditional dyeing, mainly in rural areas of Vietnam. It was found that in the past, dyeing in Vietnam was done using known plants. In the northern village of Duong Lam, cou nau was used to reproduce the dyeing of cotton cloth. Dyeing with cu nau involves exposing the surface of the cloth to sunlight to produce a darker surface, with a lighter colour on the reverse. In Tanchau, in the south, we also studied how mac nua is dyed in a factory. The cloth is silk, and the mac nua is applied to it until it is twice the weight of the cloth, and then the surface is beaten to a shiny finish, giving it a tanned leather-like texture. These were all methods of dyeing the cloth darker by repeatedly immersing it in a solution of grated plant matter in water and exposing it to the sun, without heating it during the dyeing process. Mud is also used to achieve a black colour. These fabrics were tested for properties and colourfastness.

This paper presents data on indigo coloration and discusses the characteristics of indigo coloration. The blue color dyed with indigo is versatile. The hue changes with the lightness of the color, with a greenish tint in light colors and a reddish tint in dark colors. A pure blue color with a hue angle of 270° for slightly darker colors with L^＊ of 25 to 40. The blue color of indigo has low chroma.
In the analysis of old indigo-dyed fabrics, not all of them were dyed only with indigo. Before the modern era, the dark blue color of the common people in Japan was sometimes mixed with indigo and other colorants. Synthetic dyes such as tsuya-indigo, which have a different molecular structure from indigo, were sometimes regarded as a type of indigo dyeing. Tsuya-indigo dyes a brighter color than indigo, it can be differentiated by its secondary derivative spectrum.
The coloring of silk from the indigo vat dyeing method and the raw leaf dyeing method was not the same. The raw leaf dyeing method was characterized by a greenish blue color. The color of silk dyed with red colors such as indirubin was a warm purple or red, but with low chroma.

This paper reports on the current status of research aimed at scientifically elucidating the advanced dyeing techniques used at the Heian period court. Ancient dyed textiles retain their vivid colors even today, and it is believed that these techniques have been lost. In particular, two dyeing techniques described in the Engishiki, “Karakurenai” and “Kourozen”, will be discussed. Karakurenai is a bright pink color made from safflower. There are relatively many previous studies on safflower. The search for ancient dyeing techniques has made some progress with reference to those and the dyeing methods of the Edo period. However, some points remain unexplored, such as the role of wheat bran and the effect of temperature on dyeing. Kourozen is a yellowish-brown color made of haze and suou, and is shrouded in so many mysteries, such as the large amount of suou used and the dyeing method described in the Engishiki that the author has yet to publish substantial research. Many aspects of ancient dyeing techniques remain to be clarified. Further experiments and literature research will help to unravel the mystery of how ancient dyers created these beautiful colors.