There are points other than "how to choose a color" such as temperature, coating amount, time, etc. influence the finish.
Higher temperatures lead to faster reaction and dyeing. When it is low, the reaction is slow and it is difficult to dye. "Hair coloring agent" affects hair dyeing effect depending on temperature. Normally, leave time is set based on dyeing at room temperature 20 ~ 30 ℃. Please be careful especially in winter. Coated amount difficult part it is basically a large amount of coating amount. Since there is a temperature difference between parts of the human head, it affects dyeing. If you adjust the amount to apply the hair coloring agent depending on the place, such as painting a part that is difficult to stain like a face with a lot of gray hair or a face line, such as a lot, you can prevent unevenness from appearing on the dyeing out.
Hair which is easy to stain is as described, time for hair that does not stain is longer. Depending on the hair quality, leaving time after coating also changes somewhat. However, if you change the time stated in the item extremely it also causes uneven dyeing.