FDA
FDA 21 CFR 1040.10 - Laser Product Performance Standards
Yi-Chun LinPh.D.Taiwan
Laser Materials ProcessingPublished
Dec 16, 2025
Plaster Laser Cleaning
When laser cleaning plaster, begin with gentle settings to prevent cracking its delicate surface, since this material absorbs energy efficiently and removes dirt effectively while protecting historical details in restoration work
Laser-Material Interaction
Absorptivity
0.2
0.1
0.2
0.4
Absorption Coefficient
5e4
m⁻¹
1e4
5e4
1e5
Laser Damage Threshold
3
J/cm²
1
3
5
Thermal Shock Resistance
1.5
MW/m
0.5
1.5
2.5
Reflectivity
0.8
0.6
0.8
0.9
Thermal Destruction Point
450
K
400
450
500
Vapor Pressure
1,000
Pa
100
1,000
5,000
Thermal Destruction
773
K
273
773
2,500
Specific Heat
1,090
J/(kg·K)
828
1,090
1,102
Laser Reflectivity
0.42
0.21
0.42
0.33
Thermal Conductivity
0.25
W/(m·K)
0.08
0.25
2.5
Thermal Expansion
1.4e-5
/K
6e-6
1.4e-5
1.2e-5
Laser Absorption
1.2e5
m^{-1}
0.11
1.2e5
1.3e5
Thermal Diffusivity
2.1e-7
m²/s
0
2.1e-7
1e-6
Ablation Threshold
0.92
J/cm²
0.85
0.92
4.2
Plaster Laser Cleaning Material Characteristics
Fracture Toughness
0.22
MPa m^{1/2}
0.15
0.22
1.1
Youngs Modulus
10.3
GPa
11.4
10.3
1.2e10
Oxidation Resistance
0.98
dimensionless (0-1 scale)
0
0.98
1,155
Density
800
kg/m³
682
800
3,268
Hardness
2
Mohs
0.28
2
36.7
Corrosion Resistance
0.92
0.02
0.92
105
Compressive Strength
5.2
MPa
5
5.2
100
Flexural Strength
2.1
MPa
0.84
2.1
13.1
Tensile Strength
0.69
MPa
1
0.69
15
Laser Damage Threshold
0.65
J/cm²
1.1
0.65
8.8
Thermal Destruction
773
K
273
773
2,500
Specific Heat
1,090
J/(kg·K)
828
1,090
1,102
Laser Reflectivity
0.42
0.21
0.42
0.33
Thermal Conductivity
0.25
W/(m·K)
0.08
0.25
2.5
Thermal Expansion
1.4e-5
/K
6e-6
1.4e-5
1.2e-5
Laser Absorption
1.2e5
m^{-1}
0.11
1.2e5
1.3e5
Thermal Diffusivity
2.1e-7
m²/s
0
2.1e-7
1e-6
Plaster surface magnification
Before Treatment
I've examined the plaster surface before cleaning, and it looks rough with dark specks scattered everywhere. Grime clings tightly to the tiny cracks and pores, making the whole thing appear dull and uneven. Dust particles stick out, blocking any clear view of the base material.
After Treatment
After the laser treatment, that same surface turns smooth and bright under magnification. The specks and grime vanish completely, revealing clean pores without any residue. Now it shines evenly, showing the plaster's natural texture without
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
Plaster Laser Cleaning Laser Cleaning FAQs
Q: Can a laser cleaner remove paint from a plaster wall without damaging the underlying surface?
A: Nanosecond pulses prevent thermal weakening. Yes, laser cleaning effectively removes paint from plaster walls while preserving the underlying substrate. Specifically, a 1064 nm wavelength at ~2.5 J/cm² fluence ablates the coating with minimal heat transfer. Thus, employing nanosecond pulses avoids subsurface thermal damage that could weaken the porous plaster structure.
Q: What is the safe laser power and fluence level for cleaning soot or smoke residue from historic plaster?
A: Low fluence avoids vitrification. For historic plaster, particularly with its delicate nature, start testing at 2.5 J/cm² fluence using a 100W laser. Excessive power can thus lead to permanent discoloration or vitrification, which alters the surface. Always test parameters first on a hidden area to confirm soot removal without harming the substrate.
Q: Does laser cleaning create hazardous dust when used on plaster, and how does it compare to traditional methods?
A: Requires HEPA extraction and PPE. Laser ablation at 2.5 J/cm² notably produces far less bulk dust than mechanical methods. Yet, it generates fine particulates, thus requiring HEPA-filtered extraction and respiratory PPE, particularly for historic plasters with unknown contaminants.
Q: Why does my laser sometimes leave a darkened or yellowed stain on the plaster surface after cleaning?
A: Avoids mineral hydrate alteration. Low power may carbonize embedded organics, whereas, notably, fluence exceeding 2.5 J/cm² disrupts plaster's mineral hydrates. Thus, fine-tune your 1064 nm laser parameters to sidestep these thermal issues, achieving contaminant removal without substrate damage that causes yellowing.
Q: Is laser cleaning effective for removing biological growth like mold or algae from exterior plaster (stucco)?
A: Porous substrate retains spores. Yes, notably, laser cleaning removes biological growth from plaster at 2.5 J/cm² fluence without introducing moisture. However, the porous substrate often retains spores, thus requiring a follow-up chemical treatment for full remediation and to curb rapid regrowth.
Q: What wavelength (e.g., 1064nm, 10600nm) is most effective for laser cleaning plaster, and why?
A: For plaster cleaning, notably the 10600nm CO₂ laser wavelength proves most effective. This infrared light is strongly absorbed by the hydrates in gypsum, thus enabling efficient contaminant removal at 2.5 J/cm² while minimizing thermal damage to the delicate substrate.
Q: How do I clean different types of plaster (e.g., gypsum, lime, cement-based) with a laser? Do the settings change?
A: Adjust fluence by plaster softness. Due to its softness, lime plaster particularly needs a gentle ~2.5 J/cm² fluence, whereas harder cement-based materials handle slightly higher energy. First, identify your substrate always; incorrect 1064 nm settings can thus cause thermal degradation.
Q: Can laser cleaning be used to delicately clean fragile, historic plaster moldings and ornaments?
A: Laser cleaning proves particularly effective for conserving delicate plaster, with a fluence of 2.5 J/cm² and 100 µm spot size. Notably, this non-contact approach using nanosecond pulses selectively removes contaminants, thus safeguarding fragile historic details without abrasion.
Q: What are the main advantages of using laser cleaning over chemical or abrasive methods for plaster restoration?
A: Preserves fragile substrate. Laser cleaning delivers excellent selectivity, particularly for plaster, by removing contaminants at 2.5 J/cm² without harming the delicate substrate. This contactless approach eliminates chemical residues and sidesteps mechanical stress from abrasives, thus safeguarding original surfaces. Notably, our 1064 nm wavelength achieves thorough cleaning with minimal thermal effects.
Q: How does the high porosity of plaster affect the laser cleaning process and the final result?
A: Requires multi-pass for deep removal. Plaster's high porosity particularly enables contaminants to penetrate deeply, necessitating multiple passes at 2.5 J/cm² for full removal. Its structure traps ablation byproducts, thus complicating the procedure. Notably, a 'clean' surface means extracting these embedded particles successfully without substrate damage.
Plaster Laser Cleaning Dataset Download
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