Fibers in a flowing suspension collide and lock together into flocs, especially long softwood fibers at higher consistency. The headbox breaks flocs up with turbulence, but they re-form within fractions of a second, so formation depends on how quickly the sheet is set on the wire. In the finished sheet, flocs show as dense spots separated by thinner, more translucent areas.
Long fiber was way up on the last swing and you can see the flocs from across the table.
Also heard as
- fiber floc
Related terms
Formation
How evenly fibers are spread through a paper sheet, judged by small-scale variation in mass.
Wild formation
Very uneven, blotchy formation with obvious flocs and thin areas when the sheet is held to the light.
Headbox
Pressurized box that spreads stock in a thin, even jet across the full width of the forming wire.
Look-through
Visual check of formation made by holding a sheet up to a light and judging how even or cloudy it looks.