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IR Emissivity Reference

Emissivity values for infrared temperature measurement by material and surface condition

Every infrared thermometer and thermal imaging camera requires a correct emissivity setting to produce accurate temperature readings. Emissivity is a measure of how efficiently a surface emits thermal radiation compared to a perfect blackbody (emissivity = 1.0). Most non-metallic surfaces have emissivity above 0.90, but bare metals can be as low as 0.02 for polished gold or aluminum.

Using the wrong emissivity setting is the single most common source of error in non-contact temperature measurement. A polished stainless steel surface with an emissivity of 0.15 will read dramatically low if the camera is set to the default 0.95. The error can be hundreds of degrees on hot surfaces. Conversely, a painted surface at 0.94 emissivity will read correctly at the default setting.

This reference table provides emissivity values for over 48 common industrial and building materials, organized by material type with surface condition variants (polished, oxidized, painted, rough, etc.). Values are sourced from Fluke, FLIR, and Mikron published emissivity tables and the ASNT Infrared and Thermal Testing handbook. Use these values to set your IR instrument before taking measurements.

Pro Tip: The tape trick is the most reliable field method for unknown surfaces. Apply a strip of known high-emissivity electrical tape (black vinyl tape is about 0.95) to the target, wait for thermal equilibrium (2-3 minutes on warm surfaces, longer on cold), then measure the tape at 0.95 emissivity. That is the true surface temperature. Now point at the bare surface next to the tape and adjust your emissivity setting until the reading matches. That is your surface's actual emissivity for future measurements on the same material.

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IR Emissivity Reference
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How It Works

  1. Search for Your Material

    Type the material name or browse by category. Each entry shows the material, surface condition, and emissivity value at the reference temperature range.

  2. Match the Surface Condition

    Emissivity depends heavily on surface condition. Polished copper (0.03) and heavily oxidized copper (0.78) are completely different targets. Select the condition that matches what you are actually measuring.

  3. Set Your Instrument

    Enter the emissivity value into your IR camera or pyrometer settings before taking the measurement. Most instruments default to 0.95, which is correct for painted surfaces but wrong for bare metals.

Features & Capabilities

Comprehensive Material Database

Over 48 materials with multiple surface condition variants including polished, oxidized, painted, and weathered states.

Category Organization

Organized by category: metals, non-metals, building materials, coatings, and natural materials for quick lookup.

Search and Filter

Search and filter by material name or emissivity range to quickly find the value you need.

Temperature Range Notes

Includes temperature range notes where emissivity varies significantly with temperature, so you know when published values may not apply.

Measurement Tips

Practical tips for measuring low-emissivity surfaces including the tape method and known-emissivity paint technique.

Published Sources

All values sourced from Fluke, FLIR, Mikron, and ASNT published emissivity tables with citations.

References

  • Emissivity values for total hemispherical emittance in the 8-14 micrometer atmospheric window (long-wave IR)
  • Reference temperature ranges noted where values are temperature-dependent
  • Data sourced from Fluke Technical Note on Emissivity, FLIR published emissivity tables, Mikron Instrument Company table, and ASNT Infrared and Thermal Testing Handbook
  • Values applicable to long-wave (8-14 um) and mid-wave (3-5 um) IR cameras unless otherwise noted

Frequently Asked Questions

Polished metals have very low emissivity (as low as 0.02-0.10). Your IR thermometer defaults to 0.95 emissivity, which assumes a dark, non-metallic surface. On shiny metal, most of the radiation reaching the sensor is reflected from the surroundings, not emitted by the metal. The reading will be much lower than the actual temperature.
In the long-wave infrared band (8-14 micrometers) used by most thermal cameras, paint color has minimal effect. White, black, and colored paints all have emissivity between 0.90 and 0.97. The visual color is a property of visible light wavelengths, which is independent of IR emissivity.
Apply a small piece of high-emissivity electrical tape or flat black paint to the target surface and let it reach thermal equilibrium. Measure the tape at 0.95 emissivity. Alternatively, use a contact thermocouple to get the true temperature, then adjust the emissivity setting until the IR reading matches.
Disclaimer: Emissivity values are representative and may vary based on exact alloy composition, surface roughness, oxidation state, viewing angle, and temperature. For critical measurements, determine emissivity experimentally using a contact thermocouple as reference or apply high-emissivity tape/paint to the target surface.

Learn More

Industrial

Understanding Emissivity for Infrared Temperature Measurement

What emissivity is, why it matters for IR thermometers and thermal cameras, and how to set it correctly for accurate non-contact temperature readings.

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