FrameworkApril 2026· 18 min read
LSRF-1.0 — Laser Surface Remediation Framework: Practitioner Protocol for High-Power CW Infrastructure LACR
Petr Yurchenko
Director, Laser Blasting LLC | Laser Blasting Limited
Practitioner field paper — drawn from multi-year commercial CW LACR operations. Not peer-reviewed academic research.
Abstract
A complete practitioner protocol synthesising multi-year field operational experience with high-power CW laser ablation on infrastructure. Covers thermal management (SSRT), six substrate-specific safety hazards, surface quality requirements, and coating system selection across ISO 12944 corrosivity categories C3–C5. Developed to fill the gap left by AMPP SP21511-1-2024 which covers pulsed systems only.
Why This Framework Is Needed
The existing published standard for laser ablation surface preparation — AMPP SP21511-1-2024 — covers pulsed laser systems only. A CW-specific standard is currently in development by AMPP. LSRF-1.0 fills this gap by documenting CW-specific operational parameters, hazards, and surface quality outcomes that pulsed laser guidance does not address.
The thermal behaviour of CW systems — continuous energy delivery rather than discrete pulses — produces fundamentally different substrate interactions, including the two-phase thermal model, geometry-dependent edge/centre differential, and absorptivity-driven self-limiting behaviour, none of which appear in current pulsed laser guidance.
Thermal Management — SSRT Protocol
All CW LACR operations on structural steel are managed within the two-phase thermal model:
Phase 1 (160–230°C / 320–446°F): During active coating removal. Edge geometry on hollow sections reaches 230°C; centre face 160°C. The 70°C differential requires active edge monitoring.
Phase 2 (70–90°C / 158–194°F): On bare metal after coating removal with SSRT applied. Returns to ambient within seconds. Safe for metallurgy and coating reapplication.
SSRT maintains Phase 2 temperatures within safe limits throughout extended operations. Five variables determine the thermal risk profile: substrate geometry, coating DFT, paint binder chemistry, pigment type and absorptivity at 1064nm, and coating service age and crosslink density.
Substrate Classification
Key substrate risk classifications:
Standard epoxy/inorganic paint (<130 µm DFT): LOW-MEDIUM thermal risk. Standard SSRT and PPE.
Dark/black paint (any DFT): MEDIUM-HIGH fire risk. Carbon black combustion. Fire suppression mandatory regardless of DFT.
Aged paint (10+ years): HIGH overheating risk. Increased crosslink density raises ablation threshold and thermal input. Conservative SSRT parameters required.
White/bright aged paint on hollow sections: VERY HIGH. Maximum energy input required. ThermaLog deployment recommended.
Oil-based alkyd topcoat: MEDIUM-HIGH. Delamination and flammable film ignition risk. Fire controls mandatory.
Galvanized steel — coastal: MEDIUM. ZnCl₂ explosion and ZnO metal fume fever risk. Full-face respirator and LEV mandatory.
Surface Quality Requirements
Post-LACR minimum criteria for coating application compliance:
1. Surface profile ≥35 µm per primer specification — LACR mean 74.9 µm confirmed.
2. Chloride <5 µg/cm² per SSPC-SP COM — 1.2–3 µg/cm² confirmed.
3. Visual cleanliness Sa 2.5 minimum per ISO 8501-1 — confirmed.
4. Substrate temperature <50°C per ASTM D3276 before primer — Phase 2 returns to ambient within seconds.
All four criteria confirmed met in field data.
Coating System Selection
Recommended post-LACR coating systems by corrosivity category (ISO 12944):
C3 — Urban/mild coastal: Epoxy zinc phosphate primer (50–75 µm) + high-build epoxy (100–150 µm) + polyurethane topcoat (50–75 µm). Total: 200–300 µm.
C4 — Industrial/coastal (primary LACR environment): Inorganic zinc silicate primer SSPC Paint 20 Type I (50–75 µm) + high-build epoxy (150–200 µm) + polyurethane/polyaspartic topcoat (50–75 µm). Total: 250–350 µm.
C5 — Very high industrial/marine: Inorganic zinc silicate (75 µm) + high-build epoxy two coats (200+ µm) + polyurethane topcoat (75 µm). Total: 350–450 µm.
Standards Compliance
LSRF-1.0 complements but does not replace applicable standards:
AMPP SP21511-1-2024: Covers pulsed systems. CW standard in development. LSRF-1.0 provides practitioner guidance pending formal CW standard.
SSPC-SP 6 / NACE No. 3: Commercial blast benchmark. LACR mean profile 74.9 µm at upper end of this range.
SSPC-SP 10 / NACE No. 2: Near-white blast benchmark. LACR profile within this range.
ANSI Z136.1: Laser safety — Class 4 controlled area and PPE. Mandatory for all CW LACR operations.
OSHA 1926.62: Lead in construction — applicable to all pre-1980s infrastructure LACR.
ISO 12944: Coating system selection by corrosivity category and design life.
Patents Referenced
SSRT: Patent-pending thermal management methodology for CW LACR operations on structural steel.
ThermaLog: Patent-pending real-time thermal monitoring instrument purpose-built for the CW LACR field environment.
PotShield: Patent-pending modular bearing protection system for LACR on bridge pot bearings.
Disclaimer: This is a practitioner field paper based on observations from commercial CW LACR operations. Findings are not derived from controlled laboratory testing. Substrate conditions, coating systems, and environmental factors varied across project sites. These observations are intended as a practitioner contribution to the evidence base, complementary to laboratory research rather than a substitute for it.
Author disclosure: Petr Yurchenko is Director of Laser Blasting LLC (Tennessee, USA) and Laser Blasting Limited (Auckland, New Zealand). The SSRT methodology and ThermaLog instrument referenced in this paper are patent-pending. No external funding was received.