TECHNICAL BULLETINS


Clark Solutions

Infrared Thermometers

Technical bulletin: Emissivity

 

Understanding an object's emissivity, or its characteristic "radiance" is a critical component in the proper handling of infrared measurements. Concisely, emissivity is the ratio of radiation emitted by a surface or blackbody and its theoretical radiation predicted from Planck's law [W(L,T)=C1/(L^5*(exp(C2/LT)-1)].

A material's surface emissivity is measured by the amount of energy emitted when the surface is directly observed. There are many variables that affect a specific object's emissivity, such as the wavelength of interest, field of view, the geometric shape of the blackbody, and temperature. However, for the purposes and applications of the infrared thermometer user, a comprehensive table showing the emissivity at corresponding temperatures of various surfaces and objects is displayed.

Material (Non-Metals) Temp °F (°C) Emissivity
Adobe 68 (20) 0.9
Asbestos
  Board 100 (38) 0.96
  Cement 32-392 (0-200) 0.96
  Cement, Red 2500 (1371) 0.67
  Cement, White  2500 (1371) 0.65
  Cloth 199 (93) 0.9
  Paper 100-700 (38-371) 0.93
  Slate  68 (20) 0.97
  Asphalt, pavement 100 (38) 0.93
  Asphalt, tar paper 68 (20) 0.93
Basalt 68 (20) 0.72
Brick
  Red, rough 70 (21) 0.93
  Gault Cream 2500-5000 (1371-2760) .26-.30
  Fire Clay 2500 (1371) 0.75
  Light Buff 1000 (538) 0.8
  Lime Clay 2500 (1371) 0.43
  Fire Brick 1832 (1000) .75-.80
  Magnesite, Refractory 1832 (1000) 0.38
  Grey Brick 2012 (1100) 0.75
  Silica, Glazed 2000 (1093) 0.88
  Silica, Unglazed 2000 (1093) 0.8
  Sandlime 2500-5000 (1371-2760) .59-.63
Carborundum 1850 (1010) 0.92
Ceramic
  Alumina on Inconel 800-2000 (427-1093) .69-.45
  Earthenware, Glazed 70 (21) 0.9
  Earthenware, Matte 70 (21) 0.93
  Greens No. 5210-2C 200-750 (93-399) .89-.82
  Coating No. C20A 200-750 (93-399) .73-.67
  Porcelain 72 (22) 0.92
  White Al2O3 200 (93) 0.9
  Zirconia on Inconel 800-2000 (427-1093) .62-.45
Clay 68 (20) 0.39
  Fired 158 (70) 0.91
  Shale 68 (20) 0.69
  Tiles, Light Red 2500-5000 (1371-2760) .32-.34
  Tiles, Red 2500-5000 (1371-2760) .40-.51
  Tiles, Dark Purple 2500-5000 (1371- 2760) 0.78
Concrete
  Rough 32-2000 (0-1093) 0.94
  Tiles, Natural 2500-5000 (1371-2760) .63-.62
  Brown 2500-5000 (1371-2760) .87-.83
  Black 2500-5000 (1371-2760) .94-.91
Cotton Cloth 68 (20) 0.77
Dolomite Lime 68 (20) 0.41
Emery Corundum 176 (80) 0.86
Glass
  Convex D 212 (100) 0.8
  Convex D 600 (316) 0.8
  Convex D 932 (500) 0.76
  Nonex 212 (100) 0.82
  Nonex 600 (316) 0.82
  Nonex 932 (500) 0.78
  Smooth 32-200 (0-93) .92-.94
Granite 70 (21) 0.45
Gravel 100 (38) 0.28
Gypsum 68 (20) .80-.90
Ice, Smooth 32 (0) 0.97
Ice, Rough 32 (0) 0.98
Lacquer
  Black 200 (93) 0.96
  Blue, on Al Foil 100 (38) 0.78
  Clear, on Al Foil (2 coats) 200 (93) .08-.09
  Clear, on Bright Cu 200 (93) 0.66
  Clear, on Tarnished Cu 200 (93) 0.64
  Red, on Al Foil (2 coats) 100 (38) .60-.74
  White 200 (93) 0.95
  White, on Al Foil (2 coats) 100 (38) .69-.88
  Yellow , on Al Foil (2 coats) 100 (38) .57-.79
Lime Mortar 100-500 (38-260) .90-.92
Limestone 100 (38) 0.95
Marble, White 100 (38) 0.95
  Smooth, White 100 (38) 0.56
  Polished Grey 100 (38) 0.75
Mica 100 (38) 0.75
Oil on Nickel
  0.001 Film 72 (22) 0.27
  0.002 Film 72 (22) 0.46
  0.005 Film 72 (22) 0.72
  Thick Film 72 (22) 0.82
Oil, Linseed
  On Al Foil, uncoated 250 (121) 0.09
  On Al Foil, 1 coat 250 (121) 0.56
  On Al Foil, 2 coats 250 (121) 0.51
  On Polished Iron, .001 Film 100 (38) 0.22
  On Polished Iron, .002 Film 100 (38) 0.45
  On Polished Iron, .004 Film 100 (38) 0.65
  On Polished Iron, Thick Film 100 (38) 0.83
Paints
  Blue, Cu2O3 75 (24) 0.94
  Black, CuO 75 (24) 0.96
  Green, Cu2O3 75 (24) 0.92
  Red, Fe2O3 75 (24) 0.91
  White, Al2O3 75 (24) 0.94
  White, Y2O3 75 (24) 0.9
  White, ZnO 75 (24) 0.95
  White, MgCO3 75 (24) 0.91
  White, ZrO2 75 (24) 0.95
  White, ThO2 75 (24) 0.9
  White, MgO 75 (24) 0.91
  White, PbCO3 75 (24) 0.93
  Yellow , PbO 75 (24) 0.9
  Yellow , PbCrO4 75 (24) 0.93
Paints, Aluminum 100 (38) .27-.67
  10% Al 100 (38) 0.52
  26% Al 100 (38) 0.3
  Dow XP-310 200 (93) 0.22
Paints, Bronze Low .34-.80
  Gum Varnish (2 coats) 70 (21) 0.53
  Gum Varnish (3 coats) 70 (21) 0.5
  Cellulose Binder (2 coats) 70 (21) 0.34
Paints, Oil
  All colors 200 (93) .92-.96
  Black 200 (93) 0.92
  Black Gloss 70 (21) 0.9
  Camouflage Green 125 (52) 0.85
  Flat Black 80 (27) 0.88
  Flat White 80 (27) 0.91
  Grey-Green 70 (21) 0.95
  Green 200 (93) 0.95
  Lamp Black 209 (98) 0.96
  Red 200 (93) 0.95
  White 200 (93) 0.94
Quartz, Rough, Fused 70 (21) 0.93
  Glass, 1.98 mm 540 (282) 0.9
  Glass, 1.98 mm 1540 (838) 0.41
  Glass, 6.88 mm 540 (282) 0.93
  Glass, 6.88 mm 1540 (838) 0.47
  Opaque 570 (299) 0.92
  Opaque 1540 (838) 0.68
Red Lead 212 (100) 0.93
Rubber, Hard 74 (23) 0.94
Rubber, Soft, Grey 76 (24) 0.86
Sand 68 (20) 0.76
Sandstone 100 (38) 0.67
Sandstone, Red 100 (38) .60-.83
Sawdust 68 (20) 0.75
Shale 68 (20) 0.69
Silica, Glazed 1832 (1000) 0.85
Silica, Unglazed 2012 (1100) 0.75
Silicon Carbide 300-1200 (149-649) .83-.96
Silk Cloth 68 (20) 0.78
Slate 100 (38) .67-.80
Snow, Fine Particles 20 (-7) 0.82
Snow, Granular 18 (-8) 0.89
Soil
  Surface  100 (38) 0.38
  Black Loam 68 (20) 0.66
  Plowed Field 68 (20) 0.38
Soot
  Acetylene 75 (24) 0.97
  Camphor 75 (24) 0.94
  Candle 250 (121) 0.95
  Coal 68 (20) 0.95
Stonework 100 (38) 0.93
Water 100 (38) 0.67
Waterglass 68 (20) 0.96
Wood Low .80-.90
  Beech, Planed 158 (70) 0.94
  Oak, Planed 100 (38) 0.91
  Spruce, Sanded 100 (38) 0.89

 

Material (Non-Metals) Temp °F (°C) Emissivity
Alloys
  0-Ni, 24-CR, 55-FE, Ox  392 (200) 0.9
  0-Ni, 24-CR, 55-FE, Ox 932(500) 0.97
  0-Ni, 12-CR, 28-FE, Ox 518 (270) 0.89
  0-Ni, 12-CR, 28-FE, Ox 1040 (560) 0.82
  80-Ni, 20-CR, Oxidized 212 (100) 0.87
  80-Ni, 20-CR, Oxidized 1112 (600) 0.87
  80-Ni, 20-CR, Oxidized 2372 (1300) 0.89
Aluminum
  Unoxidized 77 (25) 0.02
  Unoxidized 212 (100) 0.03
  Unoxidized 932 (500) 0.06
  Oxidized 390 (199) 0.11
  Oxidized 1110 (599) 0.19
  Oxidized at 599°C (1110°F) 390 (199) 0.11
  Oxidized at 599°C (1110°F) 1110 (599) 0.19
  Heavily Oxidized 200 (93) 0.2
  Heavily Oxidized 940 (504) 0.31
  Highly Polished 212 (100) 0.09
  Roughly Polished 212 (100) 0.18
  Commercial Sheet 212 (100) 0.09
  Highly Polished Plate 440 (227) 0.04
  Highly Polished Plate 1070 (577) 0.06
  Bright Rolled Plate 338 (170) 0.04
  Bright Rolled Plate 932 (500) 0.05
  Alloy A3003, Oxidized 600 (316) 0.4
  Alloy A3003, Oxidized 900 (482) 0.4
  Alloy 1100-0 200-800 (93-427) 0.05
  Alloy 24ST 75 (24) 0.09
  Alloy 24ST, Polished 75 (24) 0.09
  Alloy 75ST 75 (24) 0.11
  Alloy 75ST, Polished 75 (24) 0.08
Bismuth, Bright 176 (80) 0.34
Bismuth, Unoxidized 77 (25) 0.05
Bismuth, Unoxidized 212 (100) 0.06
Brass
  73% Cu, 27% Zn, Polished 476 (247) 0.03
  73% Cu, 27% Zn, Polished 674 (357) 0.03
  62% Cu, 37% Zn, Polished 494 (257) 0.03
  62% Cu, 37% Zn, Polished 710 (377) 0.04
  83% Cu, 17% Zn, Polished 530 (277) 0.03
  Matte 68 (20) 0.07
  Burnished to Brown Color 68 (20) 0.4
  Cu-Zn, Brass Oxidized 392 (200) 0.61
  Cu-Zn, Brass Oxidized 752 (400) 0.6
  Cu-Zn, Brass Oxidized 1112 (600) 0.61
  Unoxidized 77 (25) 0.04
  Unoxidized 212 (100) 0.04
  Cadmium 77 (25) 0.02
Carbon
  Lampblack 77 (25) 0.95
  Unoxidized 77 (25) 0.81
  Unoxidized 212 (100) 0.81
  Unoxidized 932 (500) 0.79
  Candle Soot 250 (121) 0.95
  Filament 500 (260) 0.95
  Graphitized 212 (100) 0.76
  Graphitized 572 (300) 0.75
  Graphitized 932 (500) 0.71
Chromium 100 (38) 0.08
Chromium 1000 (538) 0.26
Chromium, Polished 302 (150) 0.06
Cobalt, Unoxidized 932 (500) 0.13
Cobalt, Unoxidized 1832 (1000) 0.23
Columbium, Unoxidized 1500 (816) 0.19
Columbium, Unoxidized 2000 (1093) 0.24
Copper
  Cuprous Oxide 100 (38) 0.87
  Cuprous Oxide 500 (260) 0.83
  Cuprous Oxide 1000 (538) 0.77
  Black, Oxidized 100 (38) 0.78
  Etched 100 (38) 0.09
  Matte 100 (38) 0.22
  Roughly Polished 100 (38) 0.07
  Polished 100 (38) 0.03
  Highly Polished 100 (38) 0.02
  Rolled 100 (38) 0.64
  Rough 100 (38) 0.74
  Molten 1000 (538) 0.15
  Molten 1970 (1077) 0.16
  Molten 2230 (1221) 0.13
  Nickel Plated 100-500 (38-260) 0.37
Dow Metal 0.4-600 (-18-316) 0.15
Gold
  Enamel 212 (100) 0.37
  Plate (.0001) 212 (100) 0.37
  Plate on .0005 Silver 200-750 (93-399) .11-.14
  Plate on .0005 Nickel 200-750 (93-399) .07-.09
  Polished 100-500 (38-260) 0.02
  Polished 1000-2000 (538-1093) 0.03
Haynes Alloy C
  Oxidized 600-2000 (316-1093) .90-.96
Haynes Alloy 25
  Oxidized 600-2000 (316-1093) .86-.89
Haynes Alloy X
  Oxidized 600-2000 (316-1093) .85-.88
Inconel Sheet 1000 (538) 0.28
Inconel Sheet 1200 (649) 0.42
Inconel Sheet 1400 (760) 0.58
Inconel X, Polished 75 (24) 0.19
Inconel B, Polished 75 (24) 0.21
Iron
  Oxidized 212 (100) 0.74
  Oxidized 930 (499) 0.84
  Oxidized 2190 (1199) 0.89
  Unoxidized 212 (100) 0.05
  Red Rust 77 (25) 0.7
  Rusted 77 (25) 0.65
  Liquid 2760-3220 (1516-1771) .42-.45
Cast Iron
  Oxidized 390 (199) 0.64
  Oxidized 1110 (599) 0.78
  Unoxidized 212 (100) 0.21
  Strong Oxidation 40 (104) 0.95
  Strong Oxidation 482 (250) 0.95
  Liquid 2795 (1535) 0.29
Wrought Iron
  Dull 77 (25) 0.94
  Dull 660 (349) 0.94
  Smooth 100 (38) 0.35
  Polished 100 (38) 0.28
Lead
  Polished 100-500 (38-260) .06-.08
  Rough 100 (38) 0.43
  Oxidized 100 (38) 0.43
  Oxidized at 1100 100 (38) 0.63
  Gray Oxidized 100 (38) 0.28
Magnesium 100-500 (38-260) .07-.13
Magnesium Oxide 1880-3140 (1027-1727) .16-.20
Mercury 32 (0) 0.09
Mercury 77 (25) 0.1
Mercury 100 (38) 0.1
Mercury 212 (100) 0.12
Molybdenum 100 (38) 0.06
Molybdenum 500 (260) 0.08
Molybdenum 1000 (538) 0.11
Molybdenum 2000 (1093) 0.18
Molybdenum Oxidized at 1000°F 600 (316) 0.8
Molybdenum Oxidized at 1000°F 700 (371) 0.84
Molybdenum Oxidized at 1000°F 800 (427) 0.84
Molybdenum Oxidized at 1000°F 900 (482) 0.83
Molybdenum Oxidized at 1000°F 1000 (538) 0.82
Monel, Ni-Cu 392 (200) 0.41
Monel, Ni-Cu 752 (400) 0.44
Monel, Ni-Cu 1112 (600) 0.46
Monel, Ni-Cu Oxidized 68 (20) 0.43
Monel, Ni-Cu Oxidized at 1110°F 1110 (599) 0.46
Nickel
  Polished 100 (38) 0.05
  Oxidized 100-500 (38-260) .31-.46
  Unoxidized 77 (25) 0.05
  Unoxidized 212 (100) 0.06
  Unoxidized 932 (500) 0.12
  Unoxidized 1832 (1000) 0.19
  Electrolytic 100 (38) 0.04
  Electrolytic 500 (260) 0.06
  Electrolytic 1000 (538) 0.1
  Electrolytic 2000 (1093) 0.16
Nickel Oxide 1000-2000 (538-1093) .59-.86
Palladium Plate (.00005 on .0005 silver) 200-750 (93-399) .16-.17
Platinum 100 (38) 0.05
Platinum 500 (260) 0.05
Platinum 1000 (538) 0.1
Platinum, Black 100 (38) 0.93
Platinum, Black 500 (260) 0.96
Platinum, Black 2000 (1093) 0.97
Platinum Oxidized at 1100 500 (260) 0.07
Platinum Oxidized at 1100 1000 (538) 0.11
Rhodium Flash (0.0002 on 0.0005 Ni) 200-700 (93-371) .10-.18
Silver
  Plate (0.0005 on Ni) 200-700 (93-371) .06-.07
  Polished 100 (38) 0.01
  Polished 500 (260) 0.02
  Polished 1000 (538) 0.03
  Polished 2000 (1093) 0.03
Steel
  Cold Rolled 200 (93) .75-.85
  Ground Sheet 1720-2010 (938-1099) .55-.61
  Polished Sheet 100 (38) 0.07
  Polished Sheet 500 (260) 0.1
  Polished Sheet 1000 (538) 0.14
  Mild Steel, Polished 75 (24) 0.1
  Mild Steel, Smooth 75 (24) 0.12
  Mild Steel, Liquid 2910-3270 (1599-1793) 0.28
  Steel, Unoxidized 212 (100) 0.08
  Steel, Oxidized 77 (25) 0.8
Steel Alloys
  Type 301, Polished 75 (24) 0.27
  Type 301, Polished 450 (232) 0.57
  Type 301, Polished 1740 (949) 0.55
  Type 303, Oxidized 600-2000 (316-1093) .74-.87
  Type 310, Rolled 1500-2100 (816-1149) .56-.81
  Type 316, Polished 75 (24) 0.28
  Type 316, Polished 450 (232) 0.57
  Type 316, Polished 1740 (949) 0.66
  Type 321 200-800 (93-427) .27-.32
  Type 321 Polished 300-1500 (149-815) . 18-.49
  Type 321 w/BK Oxide 200-800 (93-427) .66-.76
  Type 347, Oxidized 600-2000 (316-1093) .87-.91
  Type 350 200-800 (93-427) .18-.27
  Type 350, Polished 300-1800 (149-982) .11-.35
  Type 446, Polished 300-1500 (149-815) .15-.37
  Type 17-7 PH 200-600 (93-316) .44-.51
  Type 17-7 PH Polished 300-1500 (149-815) .09-.16
  Type C1020,Oxidized 600-2000 (316-1093) .87-.91
  Type PH-15-7 MO 300-1200 (149-649) .07-.19
Stellite, Polished 68 (20)  0.18
Tantalum, Unoxidized 1340 (727) 0.14
Tantalum, Unoxidized 2000 (1093) 0.19
Tantalum, Unoxidized 3600 (1982) 0.26
Tantalum, Unoxidized 5306 (2930) 0.3
Tin, Unoxidized 77 (25) 0.04
Tin, Unoxidized 212 (100) 0.05
Tinned Iron, Bright 76 (24) 0.05
Tinned Iron, Bright 212 (100) 0.08
Titanium
  Alloy C110M,Polished 300-1200 (149-649) .08-.19
  Oxidized at 538°C (1000°F) 200-800 (93-427) .51-.61
  Alloy Ti-95A,Oxidized at 538°C (1000°F) 200-800 (93-427) .35-.48
  Anodized onto SS 200-600 (93-316) .96-.82
Tungsten
  Unoxidized 77 (25) 0.02
  Unoxidized 212 (100) 0.03
  Unoxidized 932 (500) 0.07
  Unoxidized 1832 (1000) 0.15
  Unoxidized 2732 (1500) 0.23
  Unoxidized 3632 (2000) 0.28
  Filament (Aged) 100 (38) 0.03
  Filament (Aged) 1000 (538) 0.11
  Filament (Aged) 5000 (2760) 0.35
Uranium Oxide 1880 (1027) 0.79
Zinc
  Bright, Galvanized 100 (38) 0.23
  Commercial 99.1% 500 (260) 0.05
  Galvanized 100 (38) 0.28
  Oxidized 500-1000 (260-538) 0.11
  Polished 100 (38) 0.02
  Polished 500 (260) 0.03
  Polished 1000 (538) 0.04
  Polished 2000 (1093) 0.06