Yankee dryer
A device that dries paper as it comes off the wet end of the papermaking machine by pressing one side against a cylinder that steam-heats it and imparts a glazed finish at the same time.

Yellow
Hue off a subtractive primary and a four-color process ink. It reflects red and green light, and absorbs blue light.

Yellowing
Describes a transformation inherent to all vegetable fibers that is caused by aging. Paper made of vegetable fibers will turn various degrees of yellow as its environment couples with aging to produce this phenomenon. Yellowing is very evident in groundwood papers and only a few hours in direct sunlight is enough to yellow newspaper.