Does highlighting the hair invalidate ablution for prayer, and is it considered an insulating substance?

Applying hair dye (mish) to the hair after performing ablution (wudu') does not invalidate it. One should differentiate between substances that have a physical mass (jirm) preventing water from reaching the skin, which must be removed, and those that do not have such a mass, thus not affecting the ablution. Hair dye does not have a physical mass; it is a color like henna that does not prevent water from reaching the hair.