Water or aqueous solutions, particularly alcohol or urea have been used to soften or flatten parchment. These materials sometimes alter the appearance of parchment, leaving it more transparent. This problem was investigated in regard to the pressure used during treatment, and artificial aging of the parchment beforehand. It is concluded that the use of water or water/alcohol mixture is preferred for flattening parchment, but an aqueous solution of urea is preferable for unsticking manuscripts that have become glued together.