Tideline
Definition
A concentrated deposit of dissolved ink chromophores, sizing agents, and mineral salts left at the advancing edge of a receding water front as a wet document dries; tidallines produce characteristic concentric or arc-shaped bands that can be mistaken for deliberate ink smearing.
- Cause
- Ink chromophores and salts deposited at a receding water front
- Appearance
- Concentric or arc-shaped bands
- Risk
- Mistaken for deliberate ink smearing or alteration
- Domain
- Water-damaged and wet document restoration
Common questions
How does a document examiner tell a tideline apart from deliberate smearing?+
A tideline follows the physical geometry of how the water dried, typically a curved front radiating from where the water entered or pooled, whereas deliberate smearing follows the direction of a hand or instrument and does not respect the drying pattern.
Does a tideline destroy the ink evidence underneath it?+
Not necessarily. The tideline is a concentration of dissolved material at the drying edge, and ink within the band can sometimes still be examined with infrared or alternate light imaging even though it looks visually disturbed.
Related terms
- Cockling
- The wavy planar distortion of a paper sheet caused by differential shrinkage between areas that dried at different rates, typically visible as...
- Controlled Air Drying
- Drying of a wet document flat on acid-free blotter at controlled temperature (18-20°C) and relative humidity (45-55%), separated from adjacent pages, with...
- Freeze-Drying (Vacuum Lyophilisation)
- A drying technique in which water is first frozen and then sublimed under reduced pressure (below 611 Pa), bypassing the liquid phase....
- HPMC (Hydroxypropyl Methylcellulose)
- A water-reversible cellulose ether polymer used in dilute aqueous solution as an ink fixative; applied by atomiser to wet document surfaces to...
- Ink-Fixative Pretreatment
- Application of a dilute reversible polymer solution (HPMC, Cellugel) to the surface of a still-wet document before drying, forming a gel film...
- Mould Remediation
- The physical removal of established mould colonies from a document surface, typically by soft-bristle brush under HEPA-filtered vacuum; carried out when mould...
- Multispectral Imaging
- Photography or remote sensing in multiple wavelength bands beyond the visible spectrum, including near-infrared and short-wave infrared. Drone-mounted multispectral cameras are used...
- Saponin Treatment
- Application of a dilute aqueous saponin solution (a plant-derived surfactant) to a bloodstained document surface to reduce visible haemoglobin staining without significantly...
- Sequential Examination Protocol
- A formally agreed, documented inter-discipline sequence for examining a document that carries both handwriting or text evidence and biological evidence; the sequence...