The stress-meter ink's effect:

# The ink is transparent when cold and dark grey on a black background.
# The ink is red in a temperature range of 20 - 24.5 degrees Celsius.
# The ink is green in a temperature range of 24.5 - 25 degrees Celsius.
# At temperatures of 30-34 degrees Celsius and above, the ink is blue.
# Exposure to temperatures higher than 80 degrees Celsius for longer than one minute will drastically reduce the ink's effect and lifespan.
# Using a blade, punch or steel lashing wire on the ink will destroy its effect.

Non-standard temperature range

# can be custom-made in large batches
# is determined by the temperature range in which the ink should turn green (20-25°C, 25-30°C or 30-35°C)
# The ink will first turn red
# Blue follows green

Your printed matter.

This ink must always be used on fully matt black, perfectly dry offset ink.