A demarcation line usually distinguished by significant color difference between the edge of a stain and the material on which it is located.
Synonyms in English
|French||ligne de marée|
|Spanish||línea de marea|
|Portuguese||linha de maré|
|Italian||linea di marea|
Tide lines are the result of a chemical reaction when contaminated water reacts with soluble degradation products in textiles, upholstery, paper, leather, and other materials that have the ability to pull liquids either by wicking or capillary action through the material to the point where evaporation takes place leaving behind the contaminates and degradation products producing a line that disfigures the object and weakens it. (Winterthur 2009) Areas with tide lines can become stiff resulting in the inability of affected area to flex and move with the surrounding materials causing additional damage if care is not taken when moving the object during examination and treatment.(Winterthur 2009) Sources of contaminated water can include water infiltration from leaks and floods, and human sweat. (Everts 2012)
Treatment choices will depend on the type of material(s) the object is made from, its composition, and the agreed upon ideal state of the object as decided by the conservator and the object's owner, in addition to the composition of the residual contaminates which formed the tide line. One case study involved minor water damage to an upholstered chair. Following examination and documentation, the stained area was tested with a small amount of purified water to determine the solubility of the stain and the fabric dyes. These tests revealed that the stain was highly soluble whiles the fabric dyes were not. Treatment consisted of carefully applying a small amount of water onto the stain and then lightly pressing blotter paper to absorb the tide line. When the blotter paper no longer picked up significant staining, the area was moistened again, then using capillary action, a dry purified cellulose pulp was carefully tamped into place over the tide line resulting in its successful removal. (Winterthur 2009) Another case study involved a tide line that had developed on silkscreen. Treatment consisted of sodium brorhydride (a form of bleach that does not degrade cellulose) and deionized water. The silkscreen was placed on a suction table and "the bleach was applied by brush and, while under suction, an airbrush filled with deionized water was used to rinse residual bleach, decolorized products, and some diffuse staining from the fabric." (Hartin 2009)
Prevention of water infiltration into collection storage and display areas are key to avoiding the development of tide lines on objects. Routine inspections of likely areas of water infiltration into storage facilities and display areas such as water pipes, windows, drains, gutters, and HVAC systems in addition to periodic examination of objects will reduce the occurrence of water reaching and reacting to objects.
Everts, Sarah. "Sweat-Stained Artifacts." Artful Science, February 27, 2012. http://cenblog.org/artful-science/2012/02/27/sweat-stained-artifacts/
Hartin, Debra Daly. “Collaboration Key to Removing Stain.” CCI Newsleter, No. 29, Canadian Conservation Institute, 2009.
Minnesota Historical Society. "Connecting to Collection / Minnesota!" Minnesota Historical Society. Mat 1, 2008. http://www.mnhs.org/preserve/conservation/connectingmn/docs_pdfs/repurposedbook-plantmaterials_000.pdf.
National Archives of Austraila. Drawings | The Key to Griffin's Canberra. 2012. http://blog.naa.gov.au/preservation/category/drawings/.
Norton, Alison. "The Conservation of a Contemporary Collage." The Book and Paper Group Annual, August 3, 2011.