Wet end
Wet end turns up in 2 fields: paper optics, hydrography. Here is what it means to the people in each one.
Wet end in paper optics
Front section of a paper machine, where stock is formed into a sheet and most of the water is drained and pressed out.
It runs from the stock approach and headbox through the forming section and, in most mills' usage, the press section, where the sheet is still mostly water. Wet-end chemistry, meaning the retention aids, sizing, dyes and fillers dosed into the stock, sets much of the sheet's optical character. Crews say a problem is wet-end when it starts before the dryers.
"Shade is swinging and the dye pumps are steady, so it's a wet-end chemistry thing, check the retention."
Wet end in hydrography
The underwater parts of a survey system, such as the sonar head or towfish, as opposed to the topside electronics.
Crew shorthand for everything that goes in the water: transducers, sonar heads, towfish, sound speed sensors and their cables. The matching term dry end covers the topside processing unit, acquisition computers and displays. When a system fails, the first question is whether the fault lies at the wet end or the dry end, because swapping a sonar head means divers or a haul-out.
"Topside's fine, the fault is at the wet end, probably the cable into the sonar head."