Question Summary
Does oil, cream, or gel apply to the hair prevent water from reaching the hair when wiping in Wudu?
Answer
In the Name of Allah, the Most Merciful and Compassionate
Oils and creams do not prevent water from reaching the skin when washing, so a fortiori does not prevent wiping. [Shurunbulali, Maraqi al-Falah]
On the other hand, Gel, if very thick, may prevent the wet hand from contacting the hair. For this reason, it would be most cautious not to use thick layers of hair gel.
If only a thin layer of gel, the basis is that the water reaches.
Considerations
Note that the obligation of wiping is fulfilled if one wipes one-fourth of their head. If one uses gel to style their hair for work or other important purposes that one cannot excuse themselves from, one can put the gel on the top of their head and make their wiping on the sides.
Keep in mind though the wiping must occur on any part of the head above the ear level. [Ibid]
Hope this helps
Allah knows best
[Shaykh] Yusuf Weltch
Checked and Approved by Shaykh Faraz Rabbani