Believe it or not, paper can be washed. It is a controlled process that must be monitored closely. As the chemical components within paper naturally decompose over time, it can become more acidic. Washing acidic paper in an alkaline solution draws those destructive acids out. This has two important benefits: first, it makes the paper less acidic, and therefore less brittle/more stable. Second, the acidic byproducts that are being drawn out in the wash water tend to be yellow, so removing them lightens the color of the paper once it dries.
A large, torn, and very discolored drawing recently came into the studio for treatment. Jamye laid the piece out in an oversized washing tray, submerged the paper in a shallow layer of alkaline water, allowed it to steep for several minutes, then carefully drained the (now yellow) water. She repeated the process several times before she was satisfied that a sufficient amount of acidic material had been removed. Now that the paper has been successfully washed, the processes of flattening, drying and mending (see below) can begin.