Security Thread
Definition
A strip of metallised biaxially-oriented PET film embedded in the paper substrate, alternating between visible (windowed) and embedded segments. May carry magnetic Fe3O4 coating and microprinted text. Detected by Raman (PET + Fe3O4 signature) and FTIR-ATR (PET ester bands).
- Material
- Metallised biaxially-oriented PET (polyethylene terephthalate) film, sometimes with magnetic Fe3O4 coating.
- Key detection methods
- Raman spectroscopy and FTIR-ATR (infrared spectroscopy).
- Feature on Indian notes
- Windowed thread with alternating 'भारत' (Bharat) and 'RBI' text, with color shift on higher denominations.
Common questions
What is a security thread on currency?+
A security thread is a thin strip of metallic or polymer material embedded into the paper substrate of banknotes. It can be seen when the note is held up to light. On Indian currency, the thread alternates between visible (windowed) segments and embedded segments, and carries microprinted text and color shift features on higher denominations.
How do forensic labs detect security threads in counterfeit investigations?+
Labs use Raman spectroscopy to identify the PET film material and any magnetic coating (Fe3O4), and FTIR-ATR (Fourier-transform infrared spectroscopy) to detect the characteristic ester bands of PET. These methods reveal whether the thread is authentic or fake.
Related terms
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- Banding
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- BOPP (Biaxially Oriented Polypropylene)
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- Daisy Wheel
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- Europol PEX (Project Ester)
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- FICN
- Fake Indian Currency Notes. Counterfeiting and trafficking attracts UAPA 1967 Sections 15 to 17 (as a terrorist act when high-quality and large-scale)...
- FICN (Fake Indian Currency Notes)
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- Fluorescent Security Ink
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- Golf Ball (IBM Selectric)
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- Goniospectrophotometry
- A spectrophotometric technique that measures reflectance spectra at multiple illumination and viewing angle combinations simultaneously, enabling quantitative characterisation of OVI colour-shift profiles...
- Machine Identification Code (MIC)
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Explained in these topics
- Counterfeit Currency: Security Features and Chemical AnalysisA strip of metallised biaxially-oriented PET film embedded in the paper substrate, alternating between visible (windowed) and embedded segments. May carry magn...
- Typescripts, Printed Matter, Currency and Mechanical ImpressionsEmbedded metallic or polymer thread visible against light; on MGNS notes it is a windowed thread with alternating 'भारत' and 'RBI' micro-text and colour shift...