Water spills can leave visible traces. Browning can occur along the centerfold or at old repairs where the paste has caused chemical deterioration of the paper. The whole map sometimes browns. The effect of staining on price depends on its visual impact and the type of map. The value of a decorative map is more affected by staining than is that of a rare map of scholarly interest.
Stains located in the blank margins are much less serious than stains in the printed area.
Sometimes this is the result of use, as in the case of maps that fold into a book. In such cases, tears or separations along the folds are relatively common. In general, tears are regarded as less serious if they are confined to the blank margin. A skilled restorer can repair tears. Such repairs are often almost invisible on the map side of the sheet.