Question

Would a non-polar liquid, such as gasoline, be more or less likely to bead up on a waxy polar surface?

Answer 1

Short answer: It depends which you mean by "waxy polar." If the surface is polar, a non‑polar liquid like gasoline will tend to bead (poor wetting). If the surface is waxy (i.e. non‑polar, low surface‑energy), gasoline is less likely to bead and will tend to spread.

Why: wetting is governed by surface energies (and "like dissolves like"). Gasoline is a low‑surface‑tension, non‑polar liquid, so it wets non‑polar/low‑energy surfaces well and spreads. By contrast, polar surfaces have strong polar interactions and generally poor adhesion to non‑polar liquids, producing a high contact angle (beading). Note also most waxy coatings are hydrophobic (repel water) but are not oleophobic — they typically do not repel oils/fuels unless specially treated (e.g., fluorinated coatings). Surface roughness, contamination, and solvent action on the wax can also change the behavior.