Tide Lines: An Example of Water Damage
Case Study: Restoration of a Water Damaged Paper with Tide Lines
- Title : Fishermen
- Author : Eugene Berman
- Technique : Ink on Paper
Eugene Berman, born in Russia, was a leading Surrealist and Neo-Romantic artist known for his imaginary landscapes, architectural fantasies, and Baroque-inspired stage designs, including work for the Metropolitan Opera. Trained in Paris and influenced by Pierre Bonnard, he was brought to the U.S. by dealer Julien Levy and exhibited alongside Salvador Dalí, Man Ray, and Marcel Duchamp. Berman spent nearly a decade in Los Angeles, inspired by Hollywood’s imagined worlds and supported by collector Wright Ludington. His work is represented in major museums and has been featured in notable exhibitions
In paper conservation, tide lines are the visible rings or bands left behind after water or moisture has partially wetted a sheet of paper and then dried.
They form because water mobilizes dissolved impurities—such as dirt, degradation products, inks, adhesives, or environmental pollutants—and carries them outward as it spreads. When the water evaporates, these impurities concentrate at the edges of the wet area, creating a darker or more opaque outline. Tide lines can appear:
- brown, yellow, gray, or slightly darker than surrounding paper
- sharply defined or softly feathered
- on both the front and back of the sheet
They are often considered stains and can weaken the paper chemically. Conservators typically reduce or eliminate tide lines through controlled washing, localized stain reduction, or chelator-assisted treatments, depending on the object’s sensitivity.
Tide Lines in Works on Paper: Formation, Risks, and Conservation Approaches
Tide lines are among the most characteristic and challenging forms of water-related damage encountered in the conservation and restoration of paper objects. Easily recognizable as irregular, discolored borders marking the edge of a water stain, they signal not only past exposure to moisture but also complex chemical and physical transformations within the paper itself. Their appearance can significantly diminish the visual integrity of an artwork, map, archival document, or book, and their stubbornness makes them a central concern in paper conservation practice.
The formation of tide lines is fundamentally tied to the movement of water through the porous structure of paper. When moisture is introduced—whether through a spill, flood, high humidity, or capillary action—it mobilizes soluble and colloidal materials embedded within the sheet. These may include sizing agents, degraded cellulose fragments, lignin derivatives, dyes, inks, adhesives, environmental pollutants, or even mold metabolites. As the water front advances through the fibers, it carries these solutes along. When the moisture front recedes during drying, the dissolved materials become concentrated at the outer margin of the wetted area. The resulting line often appears darker or more translucent than the surrounding paper, though it can also be lighter or differently colored depending on the chemistry of the displaced substances.
The significance of Tide Lines
From a conservation standpoint, tide lines are problematic for more than their aesthetic impact. The concentration of degradation products at the drying front can create localized areas of increased acidity, promoting further cellulose breakdown over time. Tide lines may also attract and retain particulate dirt, creating sharply defined and visually distracting borders. In cases involving iron-gall inks, metal-based pigments, or colored media, moisture movement can exacerbate corrosion or bleeding. Furthermore, the presence of tide lines often indicates that the paper has undergone uneven wetting and drying cycles, which may lead to distortions, cockling, or internal stress patterns.
Our approach to Tide Lines
Treatment of tide lines requires both technical skill and a nuanced understanding of paper chemistry. The most fundamental challenge is that the very process that created the tide line—selective mobilization and deposition—makes the staining highly resistant to superficial cleaning. Surface methods such as erasing, brushing, or sponging tend to have little effect, as the discoloration is embedded within the fiber network, not merely resting on top. Effective treatment must instead address the accumulated solutes by reintroducing controlled moisture, allowing them to be solubilized once again and dispersed or extracted in a more uniform manner.
One of the most widely employed strategies for such treatment is aqueous immersion washing. By fully wetting the sheet in a carefully controlled bath, the conservator can encourage the redistribution of mobile degradation products and reduce the visual impact of the tide line. Yet this method must be approached with caution. Differences in paper sizing, fiber composition, media solubility, and internal structure can produce vastly different outcomes. In recent decades, the use of conductivity as a diagnostic and control tool has offered conservators a more systematic way to evaluate washing efficiency and monitor ion exchange between the paper and bath.
Localized treatments are another option when full immersion is not feasible. Techniques such as blotter washing, suction-table extraction, and the use of controlled poultices allow conservators to target tide lines with precision. These methods rely on introducing moisture in a way that avoids further spreading and uses capillary pull or vacuum suction to draw solubilized compounds away from the paper. Suction tables, for example, permit treatment from the reverse side while maintaining the surface under restraint, reducing the risk of distortion. Chelating agents, mild surfactants, enzymes, or adjusted pH solutions may sometimes be incorporated to optimize solubility, but their use requires a clear understanding of potential interactions with media and fiber chemistry.
Ultimately, tide-line treatment exemplifies a central tenet of paper conservation: that moisture, while a potential source of damage, is also one of the most powerful tools for repair when applied with knowledge and precision. Successful reduction of tide lines restores visual unity and improves long-term stability, but the process also reinforces the significance of preventive care. Proper storage, environmental control, and rapid intervention after water exposure remain the most effective ways to keep tide lines from forming in the first place.