If a person has candle wax (Sham') dried on their arm during Wudu, what is the juristic ruling regarding their Wudu?

Ablution (الوضوء): Physical Barriers & Sunnah Acts Part 1

• The Wudu is valid because wax is naturally clean.
• The Wudu is invalid because wax is a physical barrier that prevents water from contacting the skin (Basharah).
• The Wudu is valid only if they perform head wipe twice.
• One-quarter of the arm is excused.