Thermopen / Temperature Indicating Crayons


Thermopen are surface temperature indicating crayons. Thermopens indicate surface temperature by changing from a chalk mark into a liquid smear. It is applied ranging from different temperatures. These crayons are available from 50 degrees to 1000 degrees. However, we can provide with different degree crayons as per customers request.



Determining preheat and post heat temperatures during welding, annealing and stress relieving in metal fabrication. Measuring operating temperatures of transformers, motors, glass blowing, steam traps, moulds, electronic components, heat transfer application and hydraulic systems.


Thermopen / Temperature Indicating Crayon

General Directions For Use

Remove cap from plastic holder. Push Thermopen slightly out of the holder and retighten with cap. Peel protective aluminium foil to expose Thermopen. Mark the Thermopen on the surface where the temperature is to be measured. If the chalk mark turns into a liquid smear then the surface has attained the rated Thermopen temperature. If the chalk mark remains unchanged, then the surface temperature is lower than that rated for the Thermopen.


Standard Ranges in °C :

50 110 170 350 800
60 120 180 400 900
70 130 190 450 1000
80 140 200 500
90 150 250 600
100 160 300 700

We do provide for various other temperatures on request.

For more Information, fill our Enquiry Form.