Emissivity Table

What is Emissivity?

Emissivity is a measure of the efficiency in which a surface emits thermal energy. It is defined as the fraction of energy being emitted relative to that emitted by a thermally black surface (a black body). A black body is a material that is a perfect emitter of heat energy and has an emissivity value of 1. A material with an emissivity value of 0 would be considered a perfect thermal mirror.

For example, if an object had the potential to emit 100 units of energy but only emits 90 units in the real world, then that object would have an emissivity value of 0.90. In the real world, there are no perfect "black bodies" and very few perfect infrared mirrors so most objects have an emissivity between 0 and 1.

Accuracy of Emissivity Values

The accuracy of the following figures is almost impossible to guarantee as the emissivity of a surface will not only alter with regard to texture and colour but also with its actual temperature at the time of measurement. We would recommend, in the first instance, comparing measurements, found with an accurate surface probe or wire probe, and then the Infrared thermometer can be adjusted to match the correct emissivity and used for subsequent measurements.

No responsibility can be assumed by ThermoWorks for the accuracy or otherwise of the following figures.

Emissivity Table

MaterialEmissivity Value
Aluminium: anodised0.77
Aluminium: polished 0.05
Asbestos: board0.96
Asbestos: fabric0.78
Asbestos: paper0.93
Asbestos: slate0.96
Brass: highly polished0.03
Brass: oxidized0.61
Brick: common.81-.86
Brick: common, red0.93
Brick: facing, red0.92
Brick: fireclay0.75
Brick: masonry0.94
Brick: red0.90
Carbon: candle soot0.95
Carbon: graphite, filed surface0.98
Carbon: purified0.80
Cement:0.54
Charcoal: powder0.96
Chipboard: untreated0.90
Chromium: polished0.10
Clay: fired 0.91
Concrete0.92
Concrete: dry0.95
Concrete: rough.92-.97
Copper: polished0.05
Copper: oxidized0.65
Enamel: lacquer0.90
Fabric: Hessian, green0.88
Fabric: Hessian, uncoloured0.87
Fibreglass0.75
Fibre board: porous, untreated0.85
Fibre board: hard, untreated0.85
Filler: white0.88
Firebrick0.68
Formica0.94
Galvanized Pipe0.46
Glass0.92
Glass: chemical ware (partly transparent)0.97
Glass: frosted0.96
Glass: frosted0.70
Glass: polished plate0.94
Granite: natural surface0.96
Graphite: powder0.97
Gravel0.28
Gypsum0.08
Hardwood: across grain0.82
Hardwood: along grain.68-.73
Ice0.97
Iron: heavily rusted.91-.96
Lacquer: bakelite0.93
Lacquer: dull black0.97
Lampblack0.96
Limestone: natural surface0.96
Mortar0.87
Mortar: dry0.94
P.V.C..91-.93
Paint: 3M, black velvet coating 9560 series optical black@1.00
Paint: aluminium 0.45
Paint, oil: average of 16 colours0.94
Paint: oil, black, flat 0.94
Paint: oil, black, gloss 0.92
Paint: oil, grey, flat 0.97
Paint: oil, grey, gloss 0.94
Paint: oil, various colours0.94
Paint: plastic, black 0.95
Paint: plastic, white 0.84
Paper: black 0.90
Paper: black, dull0.94
Paper: black, shiny0.90
Paper: cardboard box0.81
Paper: green0.85
Paper: red 0.76
Paper: white0.68
Paper: white bond0.93
Paper: yellow0.72
Paper: tar0.92
Pipes: glazed0.83
Plaster.86-.90
Plaster: rough coat0.91
Plasterboard: untreated0.90
Plastic: acrylic, clear0.94
Plastic: black0.95
Plastic: white 0.84
Plastic paper: red0.94
Plastic paper: white0.84
Plexiglass: Perpex0.86
Plywood.83-.98
Plywood: commercial, smooth finish, dry0.82
Plywood: untreated0.83
Polypropylene0.97
Porcelain: glazed0.92
Quartz0.93
Redwood: wrought, untreated0.83
Redwood: unwrought, untreated0.84
Rubber0.95
Rubber: stopper, black0.97
Sand0.90
Skin, human0.98
Snow0.80
Soil: dry0.92
Soil: frozen0.93
Soil: saturated with water0.95
Stainless Steel0.59
Stainless Plate0.34
Steel: galvanized0.28
Steel: rolled freshly0.24
Styrofoam: insulation0.60
Tape: electrical, insulating, black0.97
Tape: masking0.92
Tile: floor, asbestos0.94
Tile: glazed0.94
Tin: burnished0.05
Tin: commercial tin-plated sheet iron0.06
Varnish: flat 0.93
Wallpaper: slight pattern, light grey0.85
Wallpaper: slight pattern, red0.90
Water:0.95
Water: distilled0.95
Water: ice, smooth 0.96
Water: frost crystals0.98
Water: snow0.85
Wood: planed0.90
Wood: panelling, light finish0.87
Wood: spruce, polished, dry0.86

 


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