Encapsulated Thermometers is an instrument for measuring temperature of acids, chlorides, sulfates, bleach, solvents, phenols, caustics and peroxides. The thermometer is made more resilient to bumps and jars. It is not unbreakable. However, if the thermometer breaks, the liquid will be retained within the Teflon jacket, therefore stopping contamination wherever the thermometer is being used. Encapsulating the thermometer in Teflon does not change the calibration of the thermometer, but it does increase the lag time. Teflon encapsulated thermometers should not be used in timed tests.