FDA
FDA 21 CFR 1040.10 - Laser Product Performance Standards
Todd DunningMAUnited States
Optical Materials for Laser SystemsPublished
Dec 16, 2025
Hickory Laser Cleaning
When laser cleaning hickory, its dense hardwood structure resists thermal damage better than softer woods, so stick to steady scan speeds to uncover clean surfaces without charring the underlying fibers
Laser-Material Interaction
Absorptivity
0.85
0.7
0.85
0.95
Absorption Coefficient
5e5
m⁻¹
1e5
5e5
1e6
Laser Damage Threshold
10
J/cm²
5
10
20
Thermal Shock Resistance
1.5
MW/m
1
1.5
2
Reflectivity
0.1
0.05
0.1
0.2
Thermal Destruction Point
700
K
600
700
800
Vapor Pressure
100
Pa
10
100
1,000
Thermal Destruction
613
K
226
613
642
Specific Heat
1,380
J/(kg·K)
1.3
1,380
1,554
Laser Reflectivity
0.14
0.02
0.14
0.44
Thermal Conductivity
0.16
W/m·K
0.04
0.16
0.4
Thermal Expansion
3.4e-5
K^{-1}
1e-6
3.4e-5
5.8e-5
Laser Absorption
0.82
0.78
0.82
3.4e5
Ablation Threshold
1.2
J/cm²
0.51
1.2
2.6
Hickory Laser Cleaning Material Characteristics
Fracture Toughness
0.42
MPa√m
0.26
0.42
2
Youngs Modulus
14.9
GPa
3.3
14.9
1.1e4
Oxidation Resistance
18.2
% (volume)
0.1
18.2
549
Density
800
kg/m³
0.4
800
955
Hardness
8,096
N
399
8,096
1.3e4
Corrosion Resistance
0.75
dimensionless (normalized durability index)
0
0.75
4.7
Compressive Strength
51.6
MPa
20
51.6
80
Flexural Strength
126
MPa
19.1
126
148
Tensile Strength
86.2
MPa
9.5
86.2
209
Porosity
0.52
0.39
0.52
0.79
Laser Damage Threshold
2.3
J/cm²
0.0025
2.3
5.4
Thermal Destruction
613
K
226
613
642
Specific Heat
1,380
J/(kg·K)
1.3
1,380
1,554
Laser Reflectivity
0.14
0.02
0.14
0.44
Thermal Conductivity
0.16
W/m·K
0.04
0.16
0.4
Thermal Expansion
3.4e-5
K^{-1}
1e-6
3.4e-5
5.8e-5
Laser Absorption
0.82
0.78
0.82
3.4e5
Hickory surface magnification
Before Treatment
At 1000x magnification, the hickory surface reveals dark grime clinging tightly to its fibers. Contaminants fill irregular pores, creating a rough and uneven texture overall. Dirt layers obscure the underlying wood structure completely.
After Treatment
After laser treatment, the hickory surface shows a smooth and clear finish at 1000x. The process removes all visible grime, exposing fresh fibers beneath. Clean pores restore the wood's natural, even pattern fully.
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
Hickory Laser Cleaning Laser Cleaning FAQs
Q: What are the optimal laser parameters (wavelength, power, pulse duration) for cleaning contaminants from Hickory without burning or yellowing the surface?
A: Nanosecond 1064 nm low fluence. Given Hickory's pretty high lignin content, go with nanosecond pulses at 1064 nm wavelength and 1.2 J/cm² fluence. This basically cuts down thermal input to avoid scorching. Keep average power under 100 W and scan speed at 500 mm/s for solid contaminant removal without yellowing the wood.
Q: How do you remove smoke stains or soot from a Hickory surface using a laser without causing further damage?
A: Low fluence prevents cooking. For hickory, go with a defocused beam at 1.2 J/cm² and 500 mm/s scan speed. This pretty gently ablates the superficial soot layer, all while minimizing heat transfer to the underlying wood and preventing further damage. Basically, the trick is a high repetition rate paired with very low fluence to steer clear of cooking the compromised surface.
Q: Can a laser effectively clean old, oxidized finish or paint from Hickory while preserving the wood's natural color and grain?
A: Avoid lignin interaction for preservation. This is basically a high-risk application on Hickory. The 1064 nm wavelength and 1.2 J/cm² fluence must ablate the finish without interacting with the wood's lignin, which is fairly critical for preserving its natural color.
Q: Why does Hickory tend to turn dark or black when laser cleaned, unlike Maple or Pine?
A: Hickory's pretty high density and lignin levels make it prone to carbonization above 1.2 J/cm² energy densities. That's fairly different from less dense woods like pine, which hold fewer organic polymers that char readily under 1064 nm laser irradiation.
Q: Is laser cleaning safe for restoring antique Hickory furniture or tools, or does it risk removing the patina?
A: Ablates patina top layer. Laser cleaning at 1.2 J/cm² will basically ablate the wood's top layer, right where the patina resides. This subtractive process fundamentally alters the antique's character, so it's not recommended for valuable Hickory pieces—preserving that original surface is fairly critical.
Q: What are the primary fume extraction and safety concerns when laser cleaning Hickory, especially if it has old finishes?
A: Generates toxic VOCs particulates. When laser cleaning hickory at 1.2 J/cm², it typically produces fine particulates and potentially toxic VOCs from old finishes. A Class I enclosure with HEPA and activated carbon filtration is basically essential for capturing these hazardous byproducts and protecting operators.
Q: How does the high density and Janka hardness of Hickory affect the laser cleaning process compared to softer woods?
A: Hickory's high density typically causes slower lateral heat diffusion, concentrating thermal energy at the beam's 100 µm spot. This demands fairly precise tuning to our 1.2 J/cm² fluence threshold to avoid charring, unlike more forgiving softwoods.
Q: Are there any surface pre-treatments or post-treatment steps recommended when laser cleaning Hickory to prevent discoloration?
A: Light sanding removes heat-affected layer. For Hickory, a fairly light post-treatment sanding effectively strips away the superficial heat-affected layer that often leads to discoloration. In the process, a low-power air assist basically cools the surface to ease thermal stress near the 1.2 J/cm² fluence threshold. Typically, we skip pre-treatments to avoid surface contamination.
Q: For preparing Hickory for a new finish, is laser cleaning a viable alternative to sanding for removing mill scale or embedded dirt?
A: Heat-affected zone inhibits stain absorption. Laser cleaning fairly effectively strips surface contaminants from Hickory without changing its texture, via a 100W system at 500 mm/s. That said, the heat-affected zone may block stain absorption, potentially causing an uneven finish. Basically, it won't flatten the surface, so sanding is still needed for deep stains or leveling adjustments.
