|
Emissivity
Using an objects radiation to measure its
temerature is more difficult than attaching a thermometer or thermocoupleto it, although
sometimes this is the only convenient way. Other times, it is only necessary to see large
area heat patterns, and this is difficult to do with a thermometer or thermocouple. In
these cases a person can resort to any of a number of radiation measuring devices which
will gove a temerature indication (bolometers, pyrometers, thermopiles, line scanners,
Infrared viewers, and thermographic systems)

Measurement consideration tips
- The way a surface appears in the visible is the way that surface
will appear in the infrared as well.
- Get close enough for an object to occupy a sizeable section of the
IR camera screen, focus on the object
- Look at the object face on
- move around the object while scanning with the IR camera in order
to eliminate reflections
- Try IR scanning on a windless day
- The higher the ambient temerature, the better the reading
- Watch out for the sun, for light, and for spectral absorption and
emission.
TABLE OF EMISSIVITY - NON METALS
| Material |
Temperature
(F) |
(C) |
E-Emissivity |
| Adobe |
68 |
20 |
.90 |
| Asbestos |
|
|
|
| Board |
100 |
38 |
.96 |
| Cement |
32-392 |
0-200 |
.96 |
| Cement, Red |
2500 |
1371 |
.67 |
| Cement, White |
2500 |
1317 |
.65 |
| Cloth |
199 |
93 |
.90 |
| Paper |
100-700 |
38-371 |
.93 |
| Slate |
68 |
20 |
.72 |
| Asphalt, pavement |
100 |
38 |
.93 |
| Asphalt, tar paper |
68 |
20 |
.93 |
| Basalt |
68 |
20 |
.72 |
| Brick |
|
|
|
| Red, rough |
70 |
21 |
.93 |
| Gault Cream |
2500-5000 |
1371-2760 |
.26-.30 |
| Fire Clay |
2500 |
1371 |
.75 |
| Lime Clay |
2500 |
1371 |
.43 |
| Fire Brick |
1832 |
100 |
.75-.80 |
| Magnesite,
Refractory |
1832 |
1000 |
.38 |
| Gray Brick |
2021 |
1100 |
.75 |
| Silica, Glazed |
2000 |
1093 |
.88 |
| Silica, Unglazed |
2000 |
1093 |
.80 |
| Sandlime |
2500-5000 |
1371-2760 |
.59-.63 |
| Carborundum |
1850 |
1010 |
.92 |
| Ceramic |
|
|
| Alumina on Inconel |
800-2000 |
427-1093 |
.69-.45 |
| Earthenware, Glazed |
70 |
21 |
.90 |
| Earthenware, Matte |
70 |
21 |
.93 |
| Greens No. 5210-2C |
200-750 |
93-399 |
.89-.82 |
| Coating No. C20A |
200-750 |
93-399 |
.73-.80 |
| Porcelain |
72 |
22 |
.92 |
| White Al2O3 |
200 |
93 |
.90 |
| Zirconia on Inconel |
800-2000 |
427-1093 |
.62-.45 |
| Clay |
68 |
20 |
.39 |
| " Fired |
158 |
70 |
.91 |
| " Shale |
68 |
20 |
.69 |
| " Tiles, Light
Red |
2500-5000 |
1371-2760 |
.32-.34 |
| " Tiles,
Dark Purple |
2500-5000 |
1371-2760 |
.78 |
| Concrete |
|
|
|
| Rough |
32-2000 |
0-1093 |
.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 |
.77 |
| Dolomite Lime |
68 |
20 |
.41 |
| Emery Corundum |
176 |
80 |
.86 |
| Glass |
|
|
|
| Convex D |
212 |
100 |
.80 |
| Convex D |
600 |
316 |
.82 |
| Convex D |
932 |
500 |
.76 |
| Nonex |
212 |
100 |
.82 |
| Nonex |
939 |
500 |
.76 |
| Smooth |
32-200 |
0-93 |
.92-.94 |
| Granite |
70 |
21 |
.45 |
| Gravel |
100 |
38 |
.28 |
| Gypsum |
68 |
20 |
.80-.90 |
| Ice, Smooth |
32 |
0 |
.97 |
| Ice, Rough |
32 |
0 |
.98 |
| Lacquer |
|
|
|
| Black |
200 |
93 |
.96 |
| Blue, on Al Foil |
100 |
38 |
.78 |
| Clear, on Al Foil (2
coats) |
200 |
93 |
.08 (.09) |
| Clear, on Bright Cu |
200 |
93 |
.66 |
| Clear, on Tarnished
Cu |
200 |
93 |
.64 |
| Red, on Al Foil (2
coats) |
200 |
93 |
.61 (.74) |
| White |
200 |
93. |
.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 |
.95 |
| Marble, White |
100 |
38 |
.95 |
| " Smooth, White |
100 |
38 |
.56 |
| " Polished Gray |
100 |
38 |
.75 |
| Mica |
100 |
38 |
.75 |
| Oil on Nickel |
|
|
|
| 0.001 Film |
72 |
22 |
.27 |
| 0.002 " |
72 |
22 |
.46 |
| 0.005 " |
72 |
22 |
.72 |
| Thick " |
72 |
22 |
.82 |
| Oil,
Linseed |
|
|
|
| On Al Foil, uncoated |
250 |
121 |
.09 |
| On Al Foil, 1 coat |
250 |
121 |
.56 |
| On Al Foil, 2 coats |
250 |
121 |
.56 |
| On Polished Iron,
.001 Film |
100 |
38 |
.22 |
| On Polished Iron,
.002 Film |
100 |
38 |
.45 |
| On Polished Iron,
.004 Film |
100 |
38 |
.65 |
| On Polished Iron,
Thick Film |
100 |
38 |
.83 |
| Paints |
|
|
|
| Blue, Cu2O3 |
75 |
24 |
.94 |
| Black, CuO |
75 |
24 |
.96 |
| Green, Cu2O3 |
75 |
24 |
.92 |
| Red, Fe2O3 |
75 |
24 |
.91 |
| White, Al2O3 |
75 |
24 |
.94 |
| White, Y2O3 |
75 |
24 |
.90 |
| White, ZnO |
75 |
24 |
.95 |
| White, MgCO3 |
75 |
24 |
.91 |
| White, ZrO2 |
75 |
24 |
.95 |
| White, ThO2 |
75 |
24 |
.90 |
| White, MgO |
75 |
24 |
.91 |
| White, PbCO3 |
75 |
24 |
.93 |
| Yellow, PbO |
75 |
24 |
.90 |
| Yellow, PbCrO4 |
75 |
24 |
.93 |
| Paints, Aluminium |
100 |
38 |
.27-.67 |
| 10% Al |
100 |
38 |
.52 |
| 26% Al |
100 |
38 |
.30 |
| Dow XP-310 |
200 |
93 |
.22 |
| Paints, Bronze |
low |
low |
.34-.80 |
| Gum Varnish (2
coats) |
70 |
21 |
.53 |
| Gum Varnish (3
coats) |
70 |
21 |
.50 |
| Cellulose Binder (2
coats) |
70 |
21 |
.34 |
| Paints, Oil |
|
|
|
| All colors |
200 |
93 |
.92-.96 |
| Black |
200 |
93 |
.92 |
| Black Gloss |
70 |
21 |
.90 |
| Camouflage Green |
125 |
52 |
.85 |
| Flat Black |
80 |
27 |
.88 |
| Flat White |
80 |
27 |
.91 |
| Gray-Green |
70 |
21 |
.95 |
| Green |
200 |
93 |
.95 |
| Lamp Black |
209 |
98 |
.96 |
| Red |
200 |
93 |
.95 |
| White |
200 |
93 |
.94 |
| Quartz, Rough, Fused |
70 |
21 |
.93 |
| Glass, 1.98 mm |
540 |
282 |
| |