Does wetting the skin of the head instead of wiping suffice for ablution?
Chapter on the Obligation of Purification
Al-Mughni
Book of Purification
Primary text
If water reaches the skin of the head but the hair is not wiped, it is not sufficient. This is because the obligation has transferred to the skin, making wiping another area invalid, analogous to wetting the inside of the beard without washing the outside. If the hair falls beyond the roots of the head's hair and one wipes over the fallen part, it is not sufficient because the head refers to what is raised and uppermost. If this fallen hair is returned and tied on top of the head, wiping over it is not sufficient as it is not part of the head structure itself. However, if the hair falls beyond its roots but not beyond the area of obligation, wiping over it suffices, as it is hair on the area of obligation, similar to hair standing on its place, which is necessary for anyone with hair.
Supporting text
If one dyes their head with something covering it or applies mud to it, wiping over the dye or mud is not sufficient, as stated regarding dye. This is because the area of obligation was not wiped directly, resembling wiping over a rag left on the head.