Bay Area overhaul shops stripping cadmium primer or chromate stacks cannot run that work through an acid methylene-chloride bath without failing ASTM F519 within 48 hours on cadmium-plated 4340 steel. Rule 8-29-305 also caps aerospace strippers at 400 g/L precursor organics or 10 mmHg vapor pressure, so the tank is not a generic solvent job. Pulsed 1064 nm lift of a YSZ topcoat has to stop before the MCrAlY: 70 percent overlap left ceramic, while the two-step bond-coat scan still leaves a 4 µm recast. Complete removal of a 200 µm four-layer coupon on A357 needed 5.09 J/cm² at 700 mm/s. Treat that coupon as a coating-stack window, not a generic aluminum number. (Photonics 10, 96 (2023); Materials 17, 2414 (2024))
MIL-C-38334 still names chemical and electrolytic cleaning of metals as its own family, so a pulsed pass does not retire that specification when the purchase order calls it out. AMS 2700 still governs passivation of corrosion-resistant steels after any process that can change the surface chemistry. Cal/OSHA Title 8 §5207 governs cadmium on plated hardware: CdU above 15 µg/g creatinine or CdB above 15 µg/L triggers medical removal, with CdB, CdU, and β2-microglobulin surveillance at the action level.
MIL-C-38334 — Chemical and electrolytic cleaning of metals remains a named cleaning family on aerospace purchase orders. Laser strip does not delete a chemical-cleaning callout; it only replaces the bath when the order allows a dry method.[1]
AMS 2700 — Passivation of corrosion-resistant steels after any process that can change surface chemistry. Stainless hardware that still needs a passivation state has to meet AMS 2700 after the strip, not assume the laser passivated it.[2]
Cal/OSHA Title 8 §5207 — CdU above 15 µg/g creatinine or CdB above 15 µg/L triggers medical removal; surveillance is CdB, CdU, and β2-microglobulin at the action level. Cadmium-plated pins, fasteners, and landing-gear steel keep this medical-removal trigger even when the strip method changes.[3]
Qualify the strip before the inspector signs. Bay Area airframe work that still has to go dry into AMS 2644 fluorescent penetrant inspection cannot treat laser as a tank replacement with no etch. A 0.0003 in (7.6 µm) pre-penetrant etch is what restores detection after smear: as-machined stock only reaches 90 percent probability of detection on a 0.4 in crack, while the etch finds cracks under 0.10 in. NADCAP (aerospace quality accreditation) under AC7108/14 still wants strip cycles approved, documented, and traceable to parts. Link the aluminum skin, Ti-6Al-4V, and paint-stack pages when those substrates set the next call. (NDE-ED material smear; Photonics 10, 96 (2023); Materials 17, 2414 (2024))
Hexavalent chromium on aerospace paint stays under Title 8 §5206 at a permissible exposure limit of 5 µg/m³, an action level of 2.5 µg/m³, and an aerospace-painting engineering waypoint of 25 µg/m³. Cadmium medical removal under §5207 Appendix A trips at CdU above 15 µg/g creatinine or CdB above 15 µg/L. Rule 8-29-305 caps aerospace strippers at 400 g/L precursor organics or 10 mmHg true vapor pressure. After 28 April 2026, EPA TSCA prohibits general commercial methylene-chloride paint removal except a workplace-chemical-protection slice for safety-critical corrosion-sensitive parts. (EPA TSCA methylene chloride (2024))
Cal/OSHA TWA/PEL: 5 µg/m³ TWA
Title 8 §5206 holds hexavalent chromium at 5 µg/m³ TWA, with a 2.5 µg/m³ action level and a 25 µg/m³ aerospace-painting engineering target.
Cal/OSHA TWA/PEL: medical removal CdU >15 µg/g creatinine
Title 8 §5207 Appendix A: CdU >15 µg/g or CdB >15 µg/L triggers medical removal.
Rule 8-29-305: <400 g/L precursor organics or true vapor pressure <10 mmHg.
Labels for the three strip points on this airframe job. A357 complete-strip lands at 5.09 J/cm². 2024 polyurethane ran at 178.25 MW/cm² and 1064 nm. Inconel ceramic cleared at 140 mm³/min with 75% overlap.
| Parameter | Value |
|---|---|
| A357 four-layer paint complete strip | 5.09 J/cm² at 700 mm/s |
| 2024, 70 µm acrylic polyurethane | 178.25 MW/cm², 1064 nm, 100 ns, 40 kHz, 500 mm/s, 50 µm |
| YSZ TBC on Inconel 718 | 140 mm³/min at 75% overlap |
A YSZ topcoat that comes off at 140 mm³/min with 75% overlap is not the same job as the MCrAlY under it. Hernandez IJPST (2019) measured the two-step 14-then-6 kHz scan that clears a 350 µm bond coat at 10 mm³/min with a 4 µm recast the NADCAP special-process accreditation strip record has to carry. Residual stress after that nanosecond strip stayed tensile at 547 MPa against −264 MPa compressive on the pristine coating, so the part is not back to the as-coated residual-stress state.
| Condition | Consequence |
|---|---|
| Nanosecond TBC and bond-coat strip that leaves 547 MPa tensile residual stress[1] | Surface is tensile versus −264 MPa compressive on the pristine coating |
| Two-step nanosecond strip of a 350 µm MCrAlY bond coat on Inconel 718[1] | 10 mm³/min removal with a 4 µm recast layer left on the metal |
Treat the A357 coupon and the 2024 polyurethane as separate windows. Photonics 10, 96 (2023) needed 5.09 J/cm² at 700 mm/s to finish a ~200 µm four-layer polyurethane and epoxy coupon; residual paint stayed at 2.55–3.82 J/cm², so that lower band is not a complete strip. Materials 17, 2414 (2024) ran a 70 µm acrylic polyurethane on 2024 aluminum at 178.25 MW/cm² with 1064 nm, 100 ns, 40 kHz, 500 mm/s, and a 50 µm spot. Do not relabel the A357 coupon as Alclad 2024-T3.
