Temperature measurement colors, also referred to as thermo or thermochromatic colors, are used in a range of 40 - 630 °C and change their color in case of temperature increase. A selection of colors of one manufacturer is provided in Table 1:
The color alteration or change can be reversible (initial color after cooling) or irreversible (color change is kept after cooling). The color pigments used in thermo colors are often complex salt compounds.
The colors are usually used by applying them or by wiping a pen over hot component or machine parts, dies, die casting molds, furnaces or by applying varnish on the cold base.
This way, for example, the temperature distribution on the surface of hot machine components can be visualized, determined and checked by applying the color.
Besides temperature measurement colors, also temperature labels or temperature measurement strips are used. These can cover a wide temperature range of (-40 + 260 °C) and indicate the maximum temperature by irreversible color change (Fig. 1).