As the title implies, this paper will discuss papermaking on-line instrumentation, concentrating on sensors for paper quality measurements. The review is intended to explore not just the techniques for measurement, but also the evolution of a particular measurement and the research behind it.
On-line instrumentation will be the primary focus, covering not only the usual structural, mechanical and appearance properties of paper but also certain water system measurements around the papermaking thin/thick stock loop. These measurements will include a discussion of the sensors pertaining to “wet end chemistry” and consistency, with their incorporation into retention control schemes.
Discussion of off-line, laboratory measurements will be included where pertinent to provide a prediction of future on-line sensor availability. The usual papermaking process measurements such as pH, temperature, level, pressure and flow will not be covered.