Titanium Dioxide (TiO2)
Definition
The white pigment in most correction fluids worldwide; opaque in visible light but largely transparent above ~800 nm near-IR, making IR transmission the primary examination method for correction-fluid obliterations.
- Role
- Primary white pigment in most correction fluids
- Visible light
- Opaque, appears as an obscuring white layer
- Near-IR (~800 nm+)
- Largely transparent
- Forensic use
- IR transmission/reflectance to read text beneath obliterations
Common questions
Why does infrared examination work on correction-fluid obliterations?+
Titanium dioxide scatters and reflects visible wavelengths strongly, which is why it hides the writing underneath, but its opacity drops sharply above roughly 800 nm. An infrared imaging system can pass through the pigment layer and record contrast from the ink or graphite trapped beneath it.
Does IR transmission recover text under every kind of correction product?+
It works reliably for TiO2-based fluids but is less effective on opaque correction tapes or fluids formulated with different, IR-absorbing pigments. Examiners test the specific product's IR behaviour before relying on the method for a given document.
Can the obliterated writing be damaged by the examination itself?+
IR transmission and reflectance imaging are non-destructive, since they use existing light sources and a camera rather than solvents or abrasion, so the document and any latent evidence on it remain intact for further testing.
Related terms
- Chemical Erasure
- Destruction of an ink's chromophore by oxidising or reducing agents (bleach, permanganate, borohydride) without physically removing paper fibres, leaving altered UV fluorescence...
- Chromophore
- The molecular subunit responsible for a dye's colour, typically a conjugated double-bond system; chemical erasure destroys the chromophore while leaving the decolourised...
- Interlineation
- Text inserted between existing lines of a document after its original execution; may be detected by ink composition differences, spatial anomalies in...
- Mechanical Erasure
- Physical removal of ink by abrasion (eraser) or shearing (blade), leaving disrupted paper fibres, altered surface texture, and residual ink in fibre...
- Nine-Point Opinion Scale
- The standard framework used by the ASQDE and most international document-examination organisations for expressing conclusions, ranging from identification through elimination with intermediate...
- Obliteration
- Covering of existing writing with an opaque layer (ink, correction fluid, or correction tape) so that the underlying text is invisible in...
- Page Substitution
- Replacement of one or more pages in a multi-page document with forgeries, detectable through paper batch inconsistencies (UV fluorescence, watermark), printing differences,...
- Sizing
- Chemicals applied to paper during manufacture to control ink absorption and surface hardness; mechanical erasure removes sizing from the affected area, allowing...
- SWGDOC
- The Scientific Working Group for Forensic Document Examination (US), which publishes standards for typewriter examination, handwriting comparison, ink analysis, and related forensic...