Water drains through this side first and carries fines and filler with it, so the wire side usually reads slightly lower in brightness and can show a faint wire-mark pattern. On Fourdrinier paper it is also the rougher of the two faces. Testers mark wire side and felt side on every sample because several optical tests depend on which face is up.
You read the wire side and the spec is on the felt side, so turn the pad over and run it again.
Pencil an arrow on the wire side pointing in the machine direction before cutting samples; once cut, sides and directions are easy to mix up.
Also heard as
- bottom side
- WS
Do not mix it up with
- Felt side: The felt side is the opposite face, the one that was on top during forming.
Related terms
Felt side
Face of the sheet that was away from the forming wire, also called the top side.
Two-sidedness
Difference in properties between the two faces of a paper sheet, such as color, brightness, gloss or texture.
Wire
Endless woven plastic fabric on which the paper web is formed and drained.
Fines
Fiber fragments and small particles that pass a fine screen and have an outsized effect on sheet optics.