How to achieve a「beautiful hair appearance」,
from the position of a hair stylist we will explain the pointers here!

Fundamentally, it has become a main thing when customers are going for specific hair services, and not requiring it to match with their lifestyles. However, it is ultimately expected of the stylists to recommend something pretty yet lasting. Think about it from that point of view. The appearance timeframe of beautiful hair, and the time it can stay beautiful; we call it an expiration date. Colour is mainly divided into 3 categories:
「fashion colour」,「(covering) grey hair」, and「bleach colour」.
What’s the interval between (dyeing) fashion colour*?
*fashion colour in Japanese is classified as dyeing the hair to make it a different hue and/or shade or tone
The entire hair length looks twice as long as the grown out roots!
Despite the difference in roots growth varying with each person, a duration of approximately 1 month is usually referred to as 1 cm~1.5 cm (of growth). Following that guideline, it will be about 3 cm in 2 months. When we refer to it as 3 cm, it is considered as measuring across a total of 6 cm when viewed from the top hair parting with both parts/sides visible. Visualising having 6 cm of dark hair (compared to the previously coloured hair), it is quite noticeable, right? Therefore, taking into consideration just the roots growth, we can use 1.5 months as a guideline (The same can be considered for covering grey hair). Regarding the lasting strength (of colour) on the hair, depending on the colour dyed and lightness of the shade, the colour will fade after a month and half or so.
Ensuring it will not result in a brassy hue even after the colour fades…
Fundamentally speaking, the colour gets rinsed out each time you shampoo your hair. After an estimated 50 hair washes in 1.5 months, it is possible for the hair colour to revert back to the shade it was before dyeing. Even so, it is characteristic for Asian hair to fade to a brassy hue. Often disliked by many. Given the above problem, we have come up with two suggestions.
Suggestion 1: Full head colour in cycles of 1.5~2 months
With each time, accumulative usage of the same colour hue (dye) will increase the quality of the colour. Dyeing over the residual colour with the same hue as before will improve the effect of dyeing, as well as enhance the colour’s lasting strength. In other words repeatedly doing full head colour, using the same hue of dye over a short period of time will bring out the colour more prominently along with longer lasting hair colour. Especially when it comes to Asian hair types that fade easily, proceeding with this method will assuredly result in a beautiful hair colour.
Suggestion 2: Retouching the roots after 1.5 months, and then proceeding to dye full head colour again within 3 months. This method establishes a foundation which provides for no gaps in between each appointment. Thus,
also preventing the overall look of the hair from turning into a ‘pudding’ head* (dark roots, light hair). Alternatively, the next time to dye (after a full head colour) can be set around 2.5 months later. By then, the colour would have faded to a certain extent. The benefit of this being that it will be easier to transit to and enjoy a new hair colour.
* ‘pudding’ head (プリン頭) is often used in Japan in reference to a dessert pudding that has a brown caramel top layer, and significantly larger yellow pudding layer
Despite wanting to change your hair colour, it is not going well due to the remaining colour impeding the new colour molecules from absorbing into the hair. Suggestion 2 will be best for people who enjoy experimenting with new hair colours.

What is the interval between (covering) grey hair?
The trick is in treating the grown section of grey/white roots with great care!
The mixture base for this is basically the same as fashion colour. Yet, the issue of concern for both of them are different. Fashion colour targets the newly grown dark roots, whereas (covering) grey hair targets newly grown white/grey roots. In this situation, Suggestion 2 is a good solution as well. However, you may consider a different option.
Suggestion 3: Retouching the roots (with dye formulated to cover grey hair) + dyeing the rest of the hair with fashion colour (formulated dye).
The reason being that the chemicals in the dye (for grey coverage) are formulated to easily darken the hair. Consequently, using it for full head colour will cause the shade to get darker and darker with each application.
Targeting only the roots with the grey coverage, and sparing the rest of the hair with fashion colour, we can prevent that from happening. A lighter shade can be maintained without it darkening eventually. Extending from Suggestion 3, highlights can be inserted to enhance the overall brightness. Making even the usual grey hair coverage an enjoyable colouring experience. This suggestion is even effective for people with sparse grey hairs. Let it be known that grey coverage does not equal dark (hair colour).
What is the interval between bleaching?
With regards to bleach, it varies depending on the design etc. Here we will focus on the scenario whereby the hair is bleached from the roots to tips and then full head colour is applied. In this situation, the interval varies for whether the faded hair will be dyed fully without retouching the roots, or whether the dark roots are bleached again to blend it with the current hair. The interval is mainly based on the time frame from when the colour fades out, to when the colour is applied again. Vibrant colours can be achieved with bleach. The downside being that the colour cannot last for long. That being said, let us introduce our recommended suggestions for bleaching hair.