Arc-en-Ciel™
Oberthur Fiduciaire (France)
Arc-en-Ciel™ (French: "Rainbow") is a level 1 printed security feature for banknotes that produces a vivid rainbow-like moire effect when the note is tilted, requiring no tools or equipment to authenticate. It sits alongside watermarks and see-through features as a primary public-facing security element, but adds a dynamic dimension that those traditional features lack.
The technology works through the precise combination of two production processes: a multicolour offset-printed screen of variable-width lines, registered exactly with a dry intaglio embossing plate. When viewed straight on, the offset colours and the embossed relief are barely distinguishable from each other. As soon as the note is tilted, the varying engraved profiles along the embossed zone generate an optical moire effect — the offset colour blends emerge clearly with smooth, progressive transitions that sweep across the design like a rainbow.
Each screen is individually adapted and customised to match the desired effects and the specific shape of the motif, meaning the feature integrates directly into the banknote's design imagery rather than appearing as a generic element. The offset line fineness is precisely calibrated to the threshold of normal human visual acuity — fine enough to produce the moire when tilted, yet still visible to the naked eye at normal viewing distance.
The requirement for a specific engraving profile in the intaglio embossing plate makes Arc-en-Ciel™ very difficult to counterfeit, as reproducing the precise interaction between the printed screen and the embossed relief demands capabilities well beyond commercially available equipment.
Authentication level: Level 1 (unaided public recognition, tilt to verify).
- Name
- Arc-en-Ciel™
- Category
- Security Feature
- Effect Types
- Latent image
- Company
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Oberthur Fiduciaire
Company Website - Product Page
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- Linked Features
- 1 security feature