The effects of book and paper conservation treatments on the intrinsic data of the artifacts are examined. The tangible data present in an object are grouped in three layers, with the third layer being associated with the object’s material properties. The wealth of information that can be drawn from the data of the third layer and their significance is discussed. The obfuscation of critical data or their complete loss after specific treatments is a possible outcome, and conservators, stakeholders and the public should be aware of what may be lost after a conservation intervention.