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Infrared Temperature Measurement

Convenient and easy - but there are some traps

by Julian Edgar

Click on pics to view larger images

At a glance...

  • Infrared thermometers allow safe and easy temperature measurement
  • The emissivity of the object being measured is critical to accuracy
  • Many infrared thermometers have a fixed emissivity value
  • Other important specs include angle of view and temp range
  • Pick with care then you have a brilliant instrument
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This article was first published in 2004

We’ve all seen them around and now they’re becoming very cheap: infrared thermometers that can remotely measure the temperature of surfaces look like God’s gift to automotive modifiers. After all, you can use them to easily measure the temperature of brakes, intercoolers, oil coolers, the sump, the airbox – you name it!

However, while there are some excellent applications for infrared temp measurement, there are also some major traps. For example, if you don’t know what you are doing, infrared temp measurement can have major errors. Like the 60 degrees C that you measure is actually 90 degrees.... Or vice versa.

What are the Benefits?

Click for larger image

Infrared thermometers are remote sensing designs. That is, you point the instrument at the surface to be measured and it reads off temperature on a digital display, without any contact having to be made. This is the major advantage over a traditional thermocouple – you don’t need to touch the surface to make the measurement. This improves safety (you won’t get your fingers burnt and the area being measured can be moving or difficult to safely access), and as you don’t need to wait for a probe to come up to temperature, the speed with which measurements can be made is high.

Emissivity

An infrared thermometer measures the amount of infrared energy given off by the object to be measured. For a given temperature, the amount of infrared energy depends on what is called the body’s emissivity. The emissivity of a perfect radiator of infrared energy, called a blackbody, is 1.

Click for larger image

However, many objects have emissivities that are less than 1, and if correction isn’t made for this change in emissivity, the temperature measurement will be wrong. If the object either (a) reflects infrared energy or (b) transmits infrared energy, the emissivity value won’t equal 1. Shiny polished surfaces, such as aluminium, are so reflective of infrared energy that accurate infrared temp measurements may not be possible.

Many infrared thermometers with fixed emissivity use a default value of 0.95. Unoxidised aluminium has an emissivity of just 0.02 at 25 degrees C, while rubber’s emissivity is 0.94. So the measurement you just made of your polished intercooler tank is likely to be way out in accuracy, but the tyre temp measurement will be just fine!

To accurately measure the temperature of a variety of surfaces, the infrared thermometer needs to be able to be programmed with the emissivity of the surface that you are working with. If the thermometer doesn’t have this capability, look for a better one or be aware that many readings (especially of shiny and light coloured surfaces) are likely to be wrong.

At the end of this article you’ll find an extensive list of emissivities of different materials at different temperatures.

Measuring Angle

Click for larger image

An infrared thermometer uses a lens to focus the infrared energy onto a sensor. To accurately measure the temperature of an object, the object should completely fill the field of view encompassed by this optical system. If the object is much smaller than the field of view, the temperature of the background will affect the measurement.

To ensure the correct field of view is being encompassed, the instrument is placed a fixed distance from the surface to be measured. In some designs, a pair of angled lights form a single dot on the surface when the instrument is the correct measuring distance. Note that a single laser sight doesn’t give you an indication of the angle of view or the correct distance.

Other Measuring Problems

You should also be aware that other factors can also influence the readings:

  • Don’t make a measurement of a surface through dust, steam, gases or rain
  • Ensure that the instrument itself is within its correct working temp range
  • Make sure that the instrument’s lens is clean eg not fogged with condensation

Interesting Car Uses for an Infrared Thermometer

  • Brake temps to see if brakes are dragging and to determine their work share
  • Engine sump temps to see if installing an undertray increases oil temps
  • Temp drop across heat exchangers – engine oil cooler, trans oil cooler, intercooler, radiator
  • Power steering fluid temp
  • Tyre temps to see handling set-up
  • Car sound amplifier temps

Different Instruments

Click for larger image

When selecting an infrared thermometer, look at these specifications:

  • Range – many infrared thermometers are limited in their response to high temperatures of the sort likely to be experienced with exhausts and brakes. However, measuring these temps in car applications is fairly rare – but you still want a max temp reading of at least 300 degrees C.
  • Accuracy – this is most affected by the ability to input different emissivities into the instrument. If the thermometer uses a fixed emissivity (eg 0.95) then any quoted accuracy is likely to be unobtainable when being used for practical purposes.
  • Emissivity – to be able to accurately measure the temperature of a variety of surfaces, the thermometer must have the capability of being programmed with different emissivities.
  • Field of View – a narrow field of view (eg 8:1) allows pinpoint temp reading.
  • Sighting – how the instrument indicates the area being measured, eg by laser or LED beams
  • Data Hold – this is important because as soon as you move the thermometer aim away from the sample area, the reading will change. In some situations, reading the display at the same time as it is pointed at the correct area can be difficult. A data hold function overcomes this problem.

Using It

Click for larger image

So after all that, is it worth buying an infrared thermometer? The answer is ‘yes’, so long as it is a good quality instrument.  If the emissivity cannot be changed, the instrument can still be used for comparative measurements – ie to determine whether a surface is getting hotter or colder over time.

Buying Used

Click for larger image

With the reduction in price of infrared thermometers, even high quality ones are these days going cheaply secondhand. This Steinel ThermoCheck was bought on eBay for about AUD$90. It has adjustable emissivity from 0.5 – 1, a range of -30 to 300 degrees C and measures a 5mm diameter field from a distance of 40mm. It uses two focused flashing LEDs to show the correct measurement distance – these form a dot when the distance is correct.

Emissivity of Materials

Adobe
Alloys
Aluminum
Asphalt
Basalt
Bismuth
Brass
Brick
Cadmium
Carbon
Carborundum
Cast iron
Ceramic
Chromium
Clay
Columbium
Concrete
Copper
Cotton cloth
Dolomite lime
Dow metal
Emery corundum
Glass
Gold
Granite
Gravel

Gypsum
Haynes Alloy C., oxidized
Haynes Alloy 25, oxidized
Haynes Alloy X., oxidized
Ice
Inconel
Iron
Lacquer
Lead
Lime mortar
Limestone
Magnesium
Magnesium oxide
Marble
Mercury
Mica
Oil on nickel
Oil, linseed
Paints
Paints, aluminum
Paints, bronze
Paints, oil
Palladium plate
Paper
Plastics (average)
Platinum

Quartz
Red lead
Rhodium flash
Rubber
Sand
Sawdust
Silica
Silver
Slate
Snow
Soil
Steel
Steel alloys
Stellite, polished
Stonework
Tantalum
Tin
Tinned iron
Titanium
Tungsten
Uranium oxide
Water
Wood
Wrought iron
Zinc

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Adobe

68

20

0.90

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Alloys:

Alloy 24ST, polished

75

24

0.90

Alloy 75ST

75

24

0.11

20-Ni, 25-Cr, 55-Fe, oxidized

392
932

200
500

0.90
0.97

60-Ni, 12-Cr, 28-Fe, oxidized

518
1040

270
560

0.89
0.82

80-Ni, 20-Cr, oxidized

212
1112
2372

100
600
1300

0.87
0.87
0.89

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Aluminum:

Unoxidized

77
212
932

25
100
500

0.02
0.03
0.06

Oxidized

390
1110

199
599

0.11
0.19

Oxidized @1110°F

390
1110

199
599

0.11
0.19

Heavily oxidized

200
940

93
504

0.20
0.31

Highly polished

212

100

0.09

Roughly polished

212

100

0.18

Commercial sheet

212

100

0.09

Highly polished plate

440
1070

227
577

0.04
0.06

Bright rolled plate

338
932

170
500

0.04
0.05

Alloy A3003, oxidized

600
900

315
482

0.40
0.40

Alloy 1100-0

200 to 800

93 to 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

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Asphalt:

Pavement

100

38

0.93

Tar paper

68

20

0.93

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Basalt

68

20

0.72

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Bismuth:

Bright

176

80

0.34

Unoxidized

77
212

25
100

0.05
0.06

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Brass:

Matte

68

20

0.07

Burnished to brown color

68

20

0.40

Cu-Zn, brass oxidized

392
752
1112

200
400
600

0.61
0.60
0.61

Unoxidized

77

25

0.04

Unoxidized

212

100

0.04

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Brick:

Red, rough

70

21

0.93

Gault cream

2500 to 5000

1371 to 2760

0.26 to 0.30

Fire clay

2500

1371

0.75

Light buff

1000

538

0.80

Lime clay

2500

1371

0.43

Fire brick

1832

1000

0.75 to 0.80

Magnesite, refractory

1832

1000

0.38

Gray brick

2012

1100

0.75

Silica, glazed

2000

1093

0.88

Silica, unglazed

2000

1093

0.80

Sandime

2500 to 5000

1371 to 2760

0.59 to 0.63

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Cadmium

77

25

0.02

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Carbon:

Lamp black

77

25

0.95

Unoxidized

77

25

0.81

Unoxidized

212
932

100
500

0.81
0.79

Candle soot

250

121

0.95

Filament

500

260

0.95

Graphitized

212
572
932

100
300
500

0.76
0.75
0.71

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Carborundum

1850

1010

0.92

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Cast iron:

Oxidized

390
1110

199
599

0.64
0.78

Unoxidized

212

100

0.21

Strong oxidation

104
482

40
250

0.95
0.95

Liquid

2795

1535

0.29

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Ceramic:

Alumina on Inconel

800 to 2000

427 to 1093

0.69 to 0.45

Earthenware, glazed

70

21

0.90

Earthenware, matte

70

21

0.93

Greens, No. 5210-2C

200 to 750

93 to 399

0.89 to 0.82

Coating, No. C20A

200 to 750

93 to 399

0.73 to 0.67

Porcelain

72

22

0.92

White, Al2O3

200

93

0.90

Zirconia on Inconel

800 to 2000

427 to 1093

0.62 to 0.45

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Chromium:

Chromium

100
1000

38
538

0.08
0.26

Chromium, polished

302

150

0.06

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Clay:

68

20

0.39

Fired

158

70

0.91

Shale

68

20

0.69

Tiles, light red

2500 to 5000

1371 to 2760

0.32 to 0.34

Tiles, red

2500 to 5000

1371 to 2760

0.40 to 0.51

Tiles, dark purple

2500 to 5000

1371 to 2760

0.78

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Columbium:

Unoxidized

1500
2000

816
1093

0.19
0.24

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Concrete:

Rough

32 to 200

0 to 93

0.94

Tiles, natural

2500 to 5000

1371 to 2760

0.63 to 0.62

Tiles, brown

2500 to 5000

1371 to 2760

0.87 to 0.83

Tiles, black

2500 to 5000

1371 to 2760

0.94 to 0.91

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Copper:

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
1970
2230

538
108
1221

0.15
0.16
0.13

Nickel plated

100 to 500

38 to 260

0.37

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Cotton cloth

68

20

0.77

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Dolomite lime

68

20

0.41

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Dow metal

0 to 600

-18 to 315

0.15

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Emery corundum

176

80

0.86

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Glass:

Convex D

212
600
932

100
315
500

0.80
0.80
0.76

Nonex

212
600
932

100
315
500

0.82
0.82
0.78

Smooth

32 to 200

0 to 93

0.92 to 0.94

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Gold:

Enamel

212

100

0.37

Plate (0.001) on 0.0005 silver

200 to 750

93 to 399

0.11 to 0.14

Plate (0.001) on 0.005 nickel

200 to 750

93 to 399

0.07 to 0.09

Polished

100 to 500
1000 to 2000

38 to 260
538 to 1093

0.02
0.03

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Granite

70

21

0.45

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Gravel

100

38

0.28

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Gypsum

68

20

0.80 to 0.90

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Haynes Alloy C., oxidized

600 to 2000

316 to 1093

0.90 to 0.96

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Haynes Alloy 25, oxidized

600 to 2000

316 to 1093

0.86 to 0.89

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Haynes Alloy X., oxidized

600 to 2000

316 to 1093

0.85 to 0.88

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Ice:

Smooth

32

0

0.97

Rough

32

0

0.98

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Inconel:

Sheet

1000
1200
1400

538
649
760

0.28
0.42
0.58

Inconel X, polished

75

24

0.19

Inconel B, polished

75

24

0.21

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Iron:

Oxidized

212
930
2190

100
499
1199

0.74
0.89
0.89

Unoxidized

212

100

0.05

Red rust

77

25

0.70

Rusted

77

25

0.65

Liquid

2760 to 3220

1516 to 1771

0.42 to 0.45

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Lacquer:

Black

200

93

0.96

Blue, on aluminum foil

100

38

0.78

Clear, on aluminum foil, 2 coats

200

93

0.08 (0.09)

Clear, on bright copper

200

93

0.66

Clear, on tarnished copper

200

93

0.64

Red, on aluminum foil, 2 coats

100

38

0.61 (0.74)

White, on aluminum foil, 2 coats

100

38

0.69 (0.88)

White

200

93

0.95

Yellow, on aluminum foil, 2 coats

100

38

0.57 (0.79)

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Lead:

Polished

100 to 500

38 to 260

0.06 to 0.08

Rough

100

38

0.43

Oxidized

100

38

0.43

Oxidized @ °F

100

38

0.63

Oxidized, gray

100

38

0.28

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Lime mortar

100 to 500

38 to 260

0.90 to 0.92

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Limestone

100

38

0.95

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Magnesium

100 to 500

38 to 260

0.07 to 0.13

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Magnesium oxide

1800 to 3140

982 to 1727

0.16 to 0.20

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Marble:

White

100

38

0.95

Smooth

100

38

0.56

Polished gray

100

38

0.75

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Mercury

32
77
100
212

0
25
38
100

0.09
0.10
0.10
0.12

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Mica

100

38

0.75

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

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

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Oil, linseed:

On aluminum foil, uncoated

250

121

0.09

On aluminum foil, 1 coat

250

121

0.56

On aluminum foil, 2 coats

250

121

0.51

On polished iron, 0.001 film

100

38

0.22

On polished iron, 0.002 film

100

38

0.45

On polished iron, 0.004 film

100

38

0.65

On polished iron, thick film

100

38

0.83

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Paints:

Blue, CO2O3

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

0.90

White, ZnO

75

24

0.95

White, MgCO3

75

24

0.91

White, ZrO2

75

24

0.95

White, ThCO2

75

24

0.90

White, MgO

75

24

0.91

White, PbCO3

75

24

0.93

Yellow, PbO

75

24

0.90

Yellow, PbCrO4

75

24

0.93

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Paints, aluminum:

100

38

0.27 to 0.67

10% Al

100

38

0.52

26% Al

100

38

0.30

DOW XP-310

200

93

0.22

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Paints, bronze:

Low

0.34 to 0.80

Gum varnish, 2 coats

70

21

0.53

Gum varnish, 3 coats

70

21

0.50

Cellulose binder, 2 coats

70

21

0.34

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Paints, oil:

All colors

200

93

0.92 to 0.96

Black

200

93

0.92

Black gloss

70

21

0.90

Camouflage green

125

52

0.85

Flat black

80

27

0.88

Flat white

80

27

0.91

Gray 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

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Palladium plate(0.00005)
on 0.0005 silver

200 to 750

93 to 399

0.16 to 0.17

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Paper:

Kraft (average non-glass)

0.90

Offset (glass)

0.50 to 0.60

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Plastics (average)

Low

0.95

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Platinum:

Platinum, black

100
500
2000

38
260
1093

0.93
0.96
0.97

Platinum, oxidized @ 1100°F

500
1000

260
538

0.07
0.11

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Quartz:

Rough, fused:

70

21

0.93

Glass, 1.98 mm

540
1540

282
838

0.90
0.41

Glass, 6.88 mm

540
1540

282
838

0.93
0.47

Opaque

570
1540

299
838

0.92
0.68

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Red lead

212

100

0.93

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Rhodium flash:
0.0002 on 0.0005 Ni

200 to 700

93 to 271

0.10 to 0.18

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Rubber:

Hard

74

23

0.94

Soft, gray

76

24

0.86

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Sand

68

20

0.76

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Sawdust

68

20

0.75

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Silica:

Glazed

1832

1000

0.85

Unglazed

2012

1100

0.75

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Silver:

Plate 0.0005 on nickel

200 to 700

93 to 271

0.06 to 0.07

Polished

100
500
1000
2000

38
260
538
1093

0.01
0.02
0.03
0.03

Slate

100

38

0.67 to 0.80

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Snow:

Fine particles

20

7

0.82

Granular

18

8

0.89

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Soil:

Surface

100

38

0.38

Black loam

68

20

0.66

Plowed field

68

20

0.38

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Steel:

Cold rolled

200

93

0.75 to 0.85

Ground sheet

1720 to 2010

938 to 1099

0.55 to 0.61

Polished sheet

100
500
1000

38
260
538

0.07
0.10
0.14

Mild steel, polished

75

24

0.10

Mild steel, smooth

75

24

0.12

Mile steel, liquid

2910 to 3270

1599 to 1799

0.28

Unoxidized

77
212

25
100

0.80
0.08

Oxidized

77

25

0.80

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Steel alloys:

Type 301, polished

75
450
1740

24
232
949

0.27
0.57
0.55

Type 303, oxidized

600 to 2000

316 to 1093

0.74 to 0.87

Type 310, rolled

1500 to 2100

816 to 1149

0.56 to 0.81

Type 316, polished

75
450
1740

24
232
949

0.28
0.57
0.66

Type 321

200 to 800

93 to 427

0.27 to 0.32

Type 321, polished

300 to 1500

149 to 816

0.18 to 0.49

Type 321, with black oxide

200 to 800

93 to 427

0.66 to 0.76

Type 347, oxidized

600 to 2000

316 to 1093

0.87 to 0.91

Type 350

200 to 800

93 to 427

0.18 to 0.27

Type 350, polished

300 to 1800

149 to 982

0.11 to 0.35

Type 446, polished

300 to 1500

419 to 816

0.15 to 0.37

Type 17-7PH

200 to 600

93 to 315

0.44 to 0.51

Type 17-7PH, polished

300 to 1500

149 to 816

0.09 to 0.16

Type C1020, oxidized

600 to 2000

316 to 1093

0.87 to 0.91

Type PH-15-7MO

300 to 1200

149 to 649

0.07 to 0.19

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Stellite, polished

68

20

0.18

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Stonework

100

38

0.93

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Tantalum:

Unoxidized

1340
2000
3600
5306

727
1093
1982
2930

0.14
0.19
0.26
0.30

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Tin:

Unoxidized

77
212

25
100

0.04
0.05

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Tinned iron:

Bright

76
212

24
100

0.05
0.08

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Titanium:

Alloy C110M, polished

300 to 1200

149 to 649

0.08 to 0.19

Alloy C110M, oxidized @ 1000°F

200 to 800

93 to 427

0.51 to 0.61

Alloy TI-95A, oxidized @ 1000°F

200 to 800

93 to 427

0.35 to 0.48

Anodized onto stainless steel

200 to 600

93 to 316

0.96 to 0.82

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Tungsten:

Unoxidized

77
212
932
1832
2732
3632

25
100
500
1000
1500
2000

0.02
0.03
0.07
0.15
0.23
0.28

Filament (aged)

100
1000
5000

38
538
2760

0.03
0.11
0.35

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Uranium oxide

1880

1027

0.79

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Water

100

38

0.93

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Wood:

Low

0.80 to 0.90

Beech, planed

158

70

0.94

Oak, planed

100

38

0.91

Spruce, sanded

100

38

0.89

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Wrought iron:

Dull

77
660

25
349

0.94
0.94

Smooth

100

38

0.35

Polished

100

38

0.28

 

MATERIAL

TEMPERATURE

EMISSIVITY

°F

°C

Zinc:

Bright galvanized

100

38

0.23

Commercial 99.1%

500

260

0.05

Galvanized

100

38

0.28

Oxidized

500 to 1000

260 to 538

0.11

Polished

100
500
1000
2000

38
260
538
1093

0.02
0.03
0.04
0.06

- Table courtesy of Cole-Parmer

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