Beading vs Sheeting
Quick answer: Beading is when water forms tight droplets on paint because the surface is very hydrophobic; sheeting is when water spreads and runs off in a continuous film. Both are valid behaviours and can be tuned by products.
What it means
Water behaviour is set by contact angle and contact-angle hysteresis (advancing vs receding angle). Hydrophobic finishes (≥90°) bead; when hysteresis is low (low sliding/roll-off angle) and/or rinse flow is high, droplets coalesce and leave in sheets—still hydrophobic. In marketing we call this “sheeting”, but the cured film remains hydrophobic.
Why it matters
- Appearance: beading gives a dramatic look after rain or rinsing.
- Drying: sheeting can leave less water to towel or blow away, speeding drying.
- Water spot risk: beads can dry into mineral spots in hard water or hot sun; sheeting often reduces spotting.
- Product choice: climate, water hardness and preference guide whether you want a beady or sheeting finish.
Where you’ll see it
In ceramic coating and sealant descriptions, maintenance guides, and demonstrations after rinsing a protected car.
Context
Car Paint Protection; Ceramic coatings
Common mistakes
- Assuming beading is always better - sheeting can be more practical in hard-water or hot conditions.
- Thinking sheeting means the coating has failed - many coatings are tuned to sheet by design.
- Equating strong beading with long-term durability - beading can fade before protection actually wears out.
- Ignoring the role of wash chemicals and toppers that temporarily change water behaviour.
- Calling sheeting “hydrophilic” on paint—fast sheeting on cars is hydrophobic with low hysteresis, not a hydrophilic coating.
- Assuming less beading = failure—surfactants or grime can mute beading; decontaminate and it returns. (Plenty of “hydrophobic rinse aids” even advertise sheeting.)
Written by Danny Argent. Last updated 06/11/2025 17:35