Expert guide

What a high spot is — physically

12 minEstimated reading time — roughly how many minutes it takes to read at a normal screen pace.

- What a high spot is exactly — and why it is not a “smear” but a polymer island.

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A high spot is the most common ceramic application defect. It forms when coating dries in one place before you wipe it off — polymers cure in a lump and stand proud of the smooth plane. Under proper light it looks like rainbow rings; water does not bead there like the surrounding area.

What a high spot is — physically

It is not a smear, not dirt. It is a local polymer island ~5–15 µm higher than the surrounding layer. It forms when:

  • Part of the coating over-flashed (solvents evaporated faster than wipe-off).
  • Or residue stayed trapped in the matrix long enough to gel into an island.
  • After wipe-off, remnants catch on surrounding towel fibres and create micro-spikes.

Visual cue: at 15–30° in sun or under a paint inspection lamp you see rainbow (interference) rings; in the shower they show spot (not uniform) beading.

Five main causes

  1. Insufficiently visible residue after panel prep. Oil, silicone, wax → coating fights them and flashes unevenly.
  2. Slow wipe-off. On high-solids pro chemistry you have 2–8 minutes; on consumer 15–25. Outside that → spot.
  3. Wrong towel direction. Second towel (buff) must go perpendicular to the first (pad), or parallel residue remains.
  4. Dirty or overly plush towels. Plush traps solvents; towel lint becomes micro-contamination.
  5. Application outside microclimate window. High panel temperature (>30 °C) or low RH (<30 %) → flash in seconds.

Prevention: 3-wave wipe-off + towel discipline

Wipe-off procedure that prevents high spots

  1. One panel per cycle

    Not the whole car at once. Hood → one apply + wipe-off cycle before doors.

  2. Watch the rainbow indicator

    Coating is ready for wipe-off when ~75–85 % of the surface shows rainbow interference. Too early or too late.

  3. First towel (pad) — 50 % overlap

    Wide strokes, light pressure. Removes most surface oil.

  4. Second towel (buff) — perpendicular to first

    Dry, clean, short strokes. Removes all interference residue.

  5. Third towel (final inspection)

    Even cleaner towel. Circular polishing motions. If you feel drag, a high spot is starting.

  6. Flip towels after each panel

    Never reuse pad as buff and vice versa. Solvents accumulate.

Lighting strategy and inspection window

Catch high spots before the inspection window closes — typically 20–40 minutes after wipe-off. After that the coating is semi-cured and chemical reactivation is harder.

Lighting strategy:

  • Main work light: 5500–6500 K, diffuse, above working height.
  • Inspection light: paint inspection lamp 90+ CRI, 10–30° to the panel.
  • Secondary check: point LED from 1.5 m, 45° angle.

Look for local rainbow rings, “milky” islands, abnormally glossy patches on matte application.

Interactive decision axis

High spot: which protocol?

Use the slider to set time since coating application. The logarithmic axis shows five zones — from wet wipe-off to fully cured coating after one week.

5 min1 h24 h3 d1 wk

Drop of same product

Protocol A — reactivation

Apply 1–2 drops of the same coating directly onto the high spot. Solvents from the fresh layer reactivate the semi-cured polymer beneath, returning it to a liquid state — wipe off immediately with both towels (pad + buff). No additional flash wait required.

Protocol A: reactivation up to 40 minutes

Works while the matrix is still semi-cured (free –OH groups, incomplete cross-link).

Protocol A — reactivation drop

  1. Identify exact high spot location

    Inspection lamp 15–30°. Mark position with towel placement.

  2. Apply 1–2 drops of same coating

    Same bottle, not another product. Solvents in the new drop reactivate polymer underneath.

  3. Dwell 30–60 seconds

    Let chemistry dissolve the existing island. No circular scrubbing.

  4. Wipe-off both towels in normal order

    Pad → buff, perpendicular. Again 3 towels as in normal application.

  5. Second light check after 5 min

    Spot should be gone. If smaller, repeat once. If unchanged, you are likely past Protocol A.

Protocol A + IR rescue (1–24 h after application)

When the matrix is harder (1–24 h after wipe-off), reactivation drops work slower. IR lamp widens the window:

  • IR distance from panel: 75–90 cm (not closer — overheating risk).
  • Target panel temperature: 60 °C max.
  • Preheat: 15 minutes before reactivation drop.
  • After IR continue Protocol A without delay.

IR softens the matrix, opens paths for solvents from the new drop, and restores –OH reactivity inside the island.

A1000 by hand (24–72 h after application)

At this stage cure is advanced enough that chemistry alone fails. Full machine work is excessive — you risk removing healthy surrounding layer.

  • FEYNLAB® A1000 (fine finishing grit) on 2" microfiber applicator.
  • Hand pressure, circular motion limited to high spot + 5 mm surround.
  • Short passes (15–20 seconds), wipe with IPA panel prep or Pure Wash as you go.
  • After levelling recoat not required if spot was small (<5 mm).

Protocol B: machine + recoat (>72 h)

Fully cured ceramic. No chemical path. The only reliable approach is machine correction and new application.

Protocol B — machine repair

  1. DA polisher + A500 or A1000

    Start finer — A1000. Foam finishing pad. If high spot remains, step to A500 + microfiber pad.

  2. Polish extended area (not just the circle)

    ~30 × 30 cm around high spot, feather edges. No hard transitions.

  3. Panel Prep thoroughly

    IPA → Panel Prep → 10 min reflash. Goal is “virginal” surface again.

  4. Recoat with feather overlap

    Apply coating with 30 % overlap into existing surrounding layer. Wipe-off outward from repaired zone.

  5. Double inspection at 20 min and 1 h

    High spots sometimes return at boundaries. Second check at one hour reveals suspect edges.

Leveling AID vs Overcoat V3 — the difference

Both can help, with different goals:

ProductPurposeWhen to use
FEYNLAB® Leveling AIDFills micro-irregularities, levels surface before recoatAfter manual A1000, before optional recoat on small panel
FEYNLAB® Overcoat V3Maintenance topcoat, restores hydrophobicity and opticsAfter Protocol B or planned every 6–12 months

Leveling AID does not fix adhesion chemistry — only optical unevenness. It is not a substitute for reactivation or recoat.

Key points

  • A high spot is a polymer island, not a smear. Reactive chemistry only works in a narrow post-application window.
  • Prevention > repair: 3-wave wipe-off, paint inspection lamp, check 20–40 min after application.
  • Protocol A works up to ~40 min (chemistry alone), A + IR extends to ~24 h.
  • After 72 h only Protocol B remains — DA polishing and recoat.
  • Leveling AID ≠ Overcoat V3 — first levels micro-irregularity, second is maintenance topcoat.

Further reading

Topic: Ceramic & science

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