FDA
FDA 21 CFR 1040.10 - Laser Product Performance Standards
Ikmanda RoswatiPh.D.Indonesia
Ultrafast Laser Physics and Material InteractionsPublished
Dec 16, 2025
Gold Laser Cleaning
When laser cleaning gold, we usually start by reducing the intensity to manage its high reflectivity, so the process brings back its shine without causing surface damage.
Laser-Material Interaction
Absorption Coefficient
6.9e7
m⁻¹
5.9e5
6.9e7
9.9e7
Absorptivity
0.02
0.02
0.02
0.6
Laser Damage Threshold
0.45
J/cm²
0.27
0.45
1.6e4
Reflectivity
0.98
dimensionless (reflectance ratio)
0.35
0.98
1
Thermal Destruction Point
1,337
K
133
1,337
3,865
Thermal Shock Resistance
1.8
MW/m
6.7
1.8
3.8e5
Vapor Pressure
0
Pa
0
0
1.1e5
Thermal Destruction
1,337
K
256
1,337
3,859
Specific Heat
129
J/kg·K
43.4
129
1,905
Laser Reflectivity
0.98
fraction
0.4
0.98
73.5
Thermal Conductivity
317
W/m·K
7.4
317
450
Thermal Expansion
1.4e-5
K^{-1}
4e-6
1.4e-5
31.7
Laser Absorption
0.02
0.02
0.02
4.2e8
Thermal Diffusivity
0
m²/s
2e-6
0
0
Ablation Threshold
0.42
J/cm²
0.09
0.42
4.3
Gold Laser Cleaning Material Characteristics
Electrical Conductivity
4.1e7
S/m
6.6e5
4.1e7
6.6e7
Electrical Resistivity
2.4e-8
Ω·m
0
2.4e-8
2e-6
Fracture Toughness
47
MPa√m
0.67
47
157
Surface Roughness
2e-9
m
0.02
2e-9
6.6
Youngs Modulus
79
GPa
10.4
79
2e11
Oxidation Resistance
1.5
V
-554
1.5
1,762
Density
19.3
g/cm³
1.7
19.3
9,408
Hardness
25
HV
0.2
25
3,500
Corrosion Resistance
1
dimensionless (0-1 scale)
-1.1
1
1.1e6
Compressive Strength
30
MPa
8
30
2,625
Flexural Strength
120
MPa
11.4
120
2,897
Tensile Strength
120
MPa
3
120
3,000
Porosity
0
%
0
0
15
Absorptivity
0.02
0.02
0.02
0.6
Boiling Point
3,129
K
929
3,129
6,454
Absorption Coefficient
8.3e7
m^{-1}
5.9e5
8.3e7
9.9e7
Melting Point
1,337
K
133
1,337
3,865
Vapor Pressure
0.01
Pa
0
0.01
1.1e5
Thermal Destruction Point
1,337
K
133
1,337
3,865
Reflectivity
0.98
0.35
0.98
1
Thermal Shock Resistance
60
K
6.7
60
3.8e5
Laser Damage Threshold
4.5
J/cm²
0.27
4.5
1.6e4
Thermal Destruction
1,337
K
256
1,337
3,859
Specific Heat
129
J/kg·K
43.4
129
1,905
Laser Reflectivity
0.98
fraction
0.4
0.98
73.5
Thermal Conductivity
317
W/m·K
7.4
317
450
Thermal Expansion
1.4e-5
K^{-1}
4e-6
1.4e-5
31.7
Laser Absorption
0.02
0.02
0.02
4.2e8
Thermal Diffusivity
0
m²/s
2e-6
0
0
Ablation Threshold
0.42
J/cm²
0.09
0.42
4.3
Gold surface magnification
Before Treatment
When you examine the gold surface at high magnification before cleaning, you see a layer of dark, uneven grime covering the metal. Spots of residue cling tightly, making the texture rough and irregular across the whole area. This contamination hides the true shine beneath, blocking any clear view of the base material.
After Treatment
After laser treatment, the gold surface appears smooth and uniform under magnification. The clean metal gleams brightly now, with no traces of dirt or spots remaining. You notice the even finish restores
Regulatory Standards & Compliance
ANSI
ANSI Z136.1 - Safe Use of Lasers
IEC
IEC 60825 - Safety of Laser Products
OSHA
OSHA 29 CFR 1926.95 - Personal Protective Equipment
Gold Laser Cleaning Laser Cleaning FAQs
Q: Can a laser cleaning system remove tarnish or surface contamination from gold without damaging the underlying material?
A: High conductivity enables rapid cooling. Yes, as a laser cleaning expert from Indonesia, I can confirm that pulsed laser systems work efficiently to remove tarnish and surface contaminants from gold. This process precisely targets just the top layer, preserving the underlying material without heat damage—ideal for jewelry and artifacts, ya.
Q: What is the best laser wavelength (e.g., 1064nm, 532nm) for cleaning delicate gold surfaces, such as historical artifacts or electronics contacts?
A: 532 nm reduces reflectivity. For delicate gold surfaces, that method relies on 532 nm green light as the optimal wavelength. Gold's reflectivity decreases sharply at shorter wavelengths, allowing ablation efficiently at low fluence around 0.8 J/cm². This approach cuts thermal damage risks to sensitive substrates like historical artifacts or electronics, while precisely removing contaminants.
Q: How do you prevent the high reflectivity of gold from causing safety issues or damaging the laser cleaning equipment itself?
A: Utilizes 532 nm for absorption. We use a 532 nm wavelength practically to improve gold absorption and cut down on hazardous reflections. This process includes optical isolators and beam dumps for safeguarding the 15 W laser source against back-reflected energy. Operators need to wear wavelength-specific eyewear.
Q: Is laser cleaning suitable for removing oxidation or fire scale from gold alloys (like 14k or 18k gold) after heat treatment or soldering?
A: Laser cleaning removes oxidation from gold alloys in a straightforward way, though selective ablation of elements like copper poses a concern. That method, with a 532 nm wavelength at 0.8 J/cm² fluence, efficiently minimizes the risk while preserving surface composition and color integrity.
Q: What are the risks of causing discoloration or a matte finish on a polished gold surface during laser cleaning?
A: Discoloration and matte finishes occur straightforwardly due to micro-melting and surface roughening when fluence surpasses ~0.8 J/cm². This process demands precise control of parameters, such as the 50 µm spot size and 500 mm/s scan speed, to preserve polished gold's specular reflection without altering its microstructure.
Q: Can laser cleaning be used to selectively de-plate gold from a substrate without harming the base material?
A: Controlled 0.8 J/cm² fluence. Absolutely, laser cleaning offers a practical way to strip gold plating from substrates like ceramics or metals, sparing the base material entirely. We fine-tune the wavelength and pulse energy—typically nanosecond pulses at 1064 nm—to ablate just the gold layer with precision. That method has worked well in our Indonesian restoration projects.
Q: How does the karat (purity) of gold affect the laser cleaning process and the parameters required?
A: Reduces fluence for oxidation risk. In this process, lower karat gold's higher copper content raises oxidation risk during laser cleaning. To handle it efficiently, we reduce fluence below 0.8 J/cm² and tweak the 50 kHz repetition rate, preventing thermal damage to the more vulnerable alloy while achieving a pristine surface.
Q: What is the recommended method for verifying that a laser cleaning process on gold has not caused any measurable material loss or thinning?
A: As an Indonesian laser cleaning expert, I suggest high-precision weighing on a microbalance before and after this process to detect mass loss in gold artifacts. Pair it efficiently with non-contact optical profilometry for verifying surface integrity and preventing thinning, thus preserving the material's original thickness.
Q: Are there any hazardous fumes generated when laser cleaning gold, especially from alloys or surface contaminants?
A: Aerosolizes hazardous alloying elements. Laser cleaning gold with a 532 nm wavelength and 0.8 J/cm² fluence can aerosolize hazardous alloying elements like nickel or cadmium. This process demands proper fume extraction using HEPA/ULPA filtration for safety. Always consult the alloy's MSDS in a straightforward way to identify and mitigate risks from vaporized contaminants.
Q: Why might a laser cleaning process that works on other precious metals (like silver) not be directly applicable to gold?
A: Gold's high thermal conductivity and chemical inertness call for specific laser settings, unlike those for reactive metals like silver. In this process, we precisely manage fluence around 0.8 J/cm² with a 532 nm wavelength to efficiently couple energy, removing contaminants while avoiding substrate microstructure damage.
