Between which characteristics is there a general uncertainty in zinc oxide eugenol impression pastes?

The general uncertainty regarding zinc oxide eugenol impression pastes often revolves around working time. Working time refers to the duration available for the clinician to manipulate the material after mixing before it begins to set. This characteristic can vary significantly depending on factors such as ambient temperature, humidity, and the specific formulation of the paste used. These variables can influence how quickly the paste begins to set once mixed, which creates variability in clinical scenarios.

When considering this uncertainty, it is essential for practitioners to be aware of the conditions under which they are working, as these will directly impact the working time. While setting time and composition are also critical characteristics, they tend to be more consistent once the specific formulation is established. Accelerators are often used to modify the properties of impression materials, but the uncertainty highlighted in the question specifically pertains to the working time as it can greatly differ depending on external factors and user handling.