High Spots / Low Spots
Quick answer: High spots are patches of ceramic coating left too thick because they were not levelled in time; low spots are areas that received too little or no coating. High spots look smudged or rainbowy; low spots often show weak hydrophobics.
What it means
During application the film must be levelled within the open window. If excess product remains, it cures proud of the surface as a visible high spot. If a section is missed or wiped too aggressively, it becomes a low spot with little or no protection. Both are application defects, not product failures.
Why it matters
- Appearance: high spots show as dull smudges, streaks or iridescent patches that do not buff away once cured.
- Performance: low spots reduce durability and water behaviour, creating uneven beading or sheeting.
- Rework cost: cured high spots usually need machine polishing to remove; low spots may require local reapplication.
- Customer perception: inconsistent feel or look undermines confidence in the coating.
Where you’ll see it
Coating instructions, quality control checks under raking light, and post-delivery inspections when customers notice patchy water behaviour after the first wash.
Context
Car Paint Protection; Ceramic coatings
Common mistakes
- Trying to wipe away a cured high spot with quick detailer - it needs polishing once fully set.
- Overloading the applicator or working areas that are too large for the conditions.
- Levelling without proper lighting, so overlaps and edges are missed.
- Assuming patchy beading means the coating has failed everywhere - it often indicates local low spots.
Written by Danny Argent. Last updated 07/11/2025 14:26