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Ikmanda Roswati
Ikmanda RoswatiPh.D.Indonesia
Ultrafast photonics and laser-matter interaction
Published
Apr 1, 2026

Paint Coatings Laser Cleaning

Requires matching the paint system and substrate pairing before setting energy, because a thin single topcoat on steel clears at a fraction of the fluence a multilayer primer stack on aluminum needs, and the substrate sets its own ceiling once the coating is gone. Paint sits as an applied, cross-linked polymer film bonded by mechanical keying and resin adhesion, not a corrosion product, so pigment load and binder chemistry decide more of the setting than the substrate alone. A surface-integrity study on laser-cleaned aluminum alloy carrying a paint layer documents that a visually bare finish does not by itself confirm the metal underneath escaped the pass undamaged (Applied Optics, 2024).

Steel damage limits, primer stacks, pigment, and lead testing

  • Does a rust-removal setting also remove paint on the same steel part?

    Requires a separate check even on the same steel part, because rust, paint, and mill scale leave at different fluence floors while bare steel itself takes damage between 5.7 and 15 J/cm2[12] (Deschenes and Fraser, 2020). A setting proven on rust can overshoot that steel damage band once the paint is already gone, so prove paint removal on its own offcut rather than reusing a rust number.

  • Does a primer coat under the topcoat need a second pass?

    Often yes. A multilayer stack with a primer under the topcoat comes off in stages rather than one sweep, since the primer layer can carry its own pigment and binder chemistry with a different absorption profile than the topcoat above it. Treat the primer as its own coupon check once the topcoat is confirmed gone.

  • Why does white paint need more energy to remove than black paint?

    Pigment load sets most of the absorption at 1064 nm. Dark pigments absorb strongly and ablate near the low end of the fluence range, while white or reflective titanium dioxide pigment reflects more of that light and often needs higher fluence or a 355 nm ultraviolet pass to finish in one sweep.

  • Does every paint job need a lead test before laser cleaning starts?

    Yes on pre-1978 coatings or any unknown coating history, because a lead test by XRF or swab confirms content before the first pass and a lead-bearing coating shifts the job from standard HEPA capture to the supplied-air respirator protocol under 29 CFR 1926.62.

  • Can the same setting strip paint and graffiti off a concrete wall?

    Usually, within the same low fluence band. Paint and graffiti coatings on concrete both come off near the low end of the fluence range, well under the roughly 8 J/cm2 point where the cement paste itself starts to spall, so one coupon-proven setting typically covers both jobs on the same wall.

Sources(1 reference)
  1. Empirical Study of Laser Cleaning of Rust, Paint, and Mill Scale from Steel Surface, Materials Processing Fundamentals 2020 doi:10.1007/978-3-030-36556-1_17 (opens in new tab) — Steel substrate damage falls between 5.7 and 15 J/cm2

Paint system comes first, then an offcut sets the safe energy band

Requires a labeled offcut before production power touches a painted part, because paint comes off across a wide energy band right up until the beam reaches the substrate's own damage limit. A nanosecond study on turbine-blade paint removal found that fluence above 35 J/cm2[1] began remelting the blade surface once the coating was already gone, while settings held below that line stripped the full coating without touching the metal underneath (MDPI Coatings, 2025).

1Read the paint system and substrate pairing off the job ticket
  • Confirm whether the system is a single topcoat or a multilayer stack with a primer underneath, since a stack needs more passes than one coat.
  • Do not treat unknown lead pigment, plastic that softens under the beam, or a callout that still requires the anodize layer under the paint as a laser job until those limits are on the ticket.
  • Note the substrate under the paint. Steel, aluminum, and composite each take damage at a different energy once the coating is gone.
2Prove the setting on a matching offcut before production power
  • Step pulsed energy upward on a labeled offcut of the same substrate and paint system until the surface reads bare with no melt sheen.
  • A turbine-blade paint removal study found fluence above 35 J/cm2[1] began remelting the blade surface once the coating was already gone, so treat that as the upper limit, not a target (MDPI Coatings, 2025).
3Hold production passes to the proven setting
  • Carry the coupon-proven number to the production lot only after a bright-light check confirms bare substrate with no melt haze.
  • Run extraction through every pass, since the coating leaves airborne particulate regardless of pigment type.
Sources(1 reference)
  1. Laser Cleaning Process for Low-Pressure Turbine Blade Paint Removal with Remelting Suppression, Coatings 2025, 15(9):1054 doi:10.3390/coatings15091054 (opens in new tab) — Fluence above 35 J/cm2 begins remelting the substrate once paint clears
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