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Emissivity in the Infrared


Emissivity Values



Emissivity is a measure of a material’s radiating efficiency. An emissivity of 1.00 implies that the material is 100% efficient at radiating energy. An emissivity of 0.20 implies that the material radiates only 20% of that which it is capable of radiating.

Tables of emissivity values are only approximated values for real materials. A range of emissivity values is usually given for many materials whose emissivity can be affected by surface roughness or finish. Additionally, thin sheets of material such as plastics may be semi-transparent in the infrared and therefore have reduced emissivity.

To optimize the surface temperature measurement of a material:


Note: Applicable for material temperatures from 0 to 250°C


Material


Alumel (Unoxidized)
Alumel (Oxidized)

Emissivity


0.10 - 0.25
0.60

Aluminum (Polished)
Aluminum (Oxidized)
Aluminum (Rough)
Aluminum (Anodized)
0.10 - 0.05
0.10 - 0.40
0.10 - 0.30
0.60 - 0.95

Aluminum Oxide

Asbestos

Asphalt

Basalt

Bismuth
0.40

0.95

0.90 - 1.00

0.70

0.50

Brass (Polished)
Brass (Oxidized)
Brass (Burnished)

Carbon (Unoxidized)
Carbon (Filament)
Carbon (Soot)
Carbon (Coke)
Carbon (Graphite)
0.05
0.50 - 0.60
0.30

0.40 - 0.90
0.50
0.50 - 0.95
0.95 - 1.00
0.70 - 0.80

Carborundum

Ceramic

Clay (Fired)

Concrete
0.80 - 0.90

0.90 - 0.95

0.95

0.95

Chrome (Oxidized)

Chromium

Cobalt
0.60 - 0.85

0.10

0.20

Columbium (Polished)
Columbium (Oxidized)

Copper (Polished)
Copper (Oxidized)
0.20
0.70

0.10
0.20 - 0.80

Electrical terminal blocks

Enamel

Foods

Formica
0.60

0.90

0.85 - 1.00

0.95

Glass (Convex D)
Glass (Nonex)
Glass (Plate)
Glass (Fused quartz)
Glass (Pyrex, lead and soda)
0.80
0.80
0.90 - 0.95
0.75
0.95

Gold:

Granite (Polished)
Granite (Rough)
Granite (Natural)

Gravel
0.05

0.85
0.90
0.95

0.90 - 0.95

Gypsum

Haynes Alloy

Human Skin
0.85 - 0.95

0.30 - 0.80

0.99

Inconel (Polished)
Inconel (Oxidized)
Inconel (Sandblasted)

Iron (Oxidized)
Iron (Rusted)
Iron (Wrought, dull)

Iron Oxide
0.15
0.70 - 0.95
0.30 - 0.66

0.50 - 0.95
0.50 - 0.70
0.90

0.85

Lacquer (Colored on Al)
Lacquer (Colored)
Lacquer (Clear on Al)
Lacquer (Clear on Cu)

Lead (Polished)
Lead (Oxidized)
Lead (Rough)
0.75 - 0.90
0.95
0.10
0.65

0.05 - 0.10
0.30 - 0.65
0.40

Limestone

Magnesium Oxide

Molybdenum (Polished)
Molybdenum (Oxidized)

Monel (Oxidized)
0.95 - 1.00

0.55

0.05
0.20 - 0.80

0.45 - 0.85

Mullite

Nichrome (Clean)
Nichrome (Oxidized)

Nickel (Polished)
Nickel (Oxidized)

Nickel Oxide
0.80 - 0.85

0.65
0.60 - 0.85

0.10
0.20 - 0.95

0.60

Oil (Animal/vegetable)
Oil (Mineral)
Oil (0.001” thick)
Oil (0.002” thick)
Oil (0.005” thick)

Paint (Aluminum paint)
Paint (Bronze paint)
Paint (on metal)
Paint (on plastic or wood)
Paint (Gold enamel)
Paint (Clear silicone)
0.95 - 1.00
0.90 - 1.00
0.25
0.46
0.70

0.50
0.80
0.60 - 0.90
0.80 - 0.95
0.40
0.65 - 0.80

Paper

Plaster

Plastic

Platinum

Polyester
0.85 - 1.00

0.90

0.95 - 1.00

0.05

0.75 - 0.85

Polyethylene

Quartz

Roofing Paper

Rubber (Hard glossy)
Rubber (Soft rough)
0.10

0.90

0.90

0.95
0.85

Sand

Sandstone

Shale

Silica (Powder)
Silica (Glazed)
Silica (Unglazed)
0.80 - 0.90

0.70

0.70

0.35 - 0.60
0.85
0.75

Silicone Carbide

Silver

Soil (Dry)
Soil (Wet)

Slate
0.80 - 0.95

0.05

0.90 - 0.95
0.95 - 1.00

0.70 - 0.80

Stainless Steel (Polished)
Stainless Steel (Oxidized)

Steel (Unoxidized)
Steel (Oxidized)
Steel (Cold Rolled)
Steel (Ground sheet)
Steel (Rough surface)
0.10 - 0.15
0.45 - 0.95

0.10
0.70 - 0.95
0.70 - 0.90
0.40 - 0.60
0.95

Tantalum (Unoxidized)
Tantalum (Oxidized)

Textiles (Carpet)
Textiles (Close weave)
Textiles (Cotton)
Textiles (Leather)
Textiles (Silk)
Textiles (Died black)
0.20
0.60

0.85 - 1.00
0.70 - 0.95
0.80
0.95 - 1.00
0.80
0.98

Tin (Unoxidized)

Tungsten (Unoxidized)
Tungsten (Filament)

Water (Liquid)
Water (Ice)
Water (Snow)
0.05 - 0.10

0.05
0.30

0.90 - 0.95
0.95 - 1.00
0.80 - 1.00

Wood (Planed)
Wood (Sawdust)

Zinc (Polished)
Zinc (Oxidized)
Zinc (Galvanized)
0.80 - 0.95
0.75

0.05
0.10
0.20 - 0.30


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