can be important in maintaining cover integrity those skilled in this art will also appreciate that the roll 10 may be constructed with a tie in layer sandwiched between the base layer 18 and the top stock layer 22 such that the tie in layer would directly underlie the top stock layer 22 the typical properties of a tie in layer are well known to those skilled in this art and need not be described in detail herein after the top stock 22 has been applied the roll 10 is then cured typically in an autoclave for a suitable curing period generally between about 16 and 30 hours after curing it is preferred that any crust that has developed is skimmed from the surface of the top stock layer 22 and that the top stock layer 22 is ground for dimensional correctness roll covers formed of the compositions described above can be employed in nip rolls or other roll positions within papermaking machines or other devices in position and during operation of the machine the roll cover due to the presence of a thermochromic and or piezochromic composition therein can provide information about the temperature and or pressure experienced by the roll cover as such undesirable circumstances such as uneven application of pressure misalignment or miscrowning of nip rolls improper roll profile overloading of the roll beyond a preselected limit the presence of u201c hot spots u201d in the cover localized wear or the like can be discerned visually during operation also photographs can be taken.