What circumstances can alter the reading of PVC?

The reading of a PVC (polyvinyl chloride) can be altered by factors such as temperature, pressure, and the presence of additives or plasticizers that affect its physical properties. Additionally, variations in the manufacturing process, such as differences in formulation or processing conditions, can lead to inconsistencies in the PVC's characteristics. Environmental conditions, such as exposure to UV light or chemicals, can also impact the performance and readings of PVC over time.