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The Value of Overt Security Features (February 2010)

At the recent Optical Document Security conference in San Francisco, Hans de Heij of the Dutch Central Bank (DNB) gave a presentation entitled ‘Innovative Approaches to the Selection of Banknote Features’. De Heij is currently doing a PhD on the key elements of banknote design and the presentation drew upon this as well as numerous studies and surveys conducted by the DNB itself and several other central banks among both the public and professional cash handlers (such as bank clerks and retailers).

The main thrust of the presentation was that, with more than 50 public security features now available for banknotes, deciding on which should remain, which new ones should be introduced and which should be dropped requires some systematic basis for decision making. In doing so, he provided some interesting insights into how security features are examined, verified and communicated, and also which are the key criteria by which the public does, or doesn’t recall those features. Although his research and the presentation was focused on banknotes, the points he made are equally applicable to any security document or label that contains features intended by the document issuer or brand owner for consumer recognition. 

One of the key elements of research is the survey that the DNB conducts every two years to measure the public’s recall of features on euro banknotes. As the table shows, the watermark came out top in the latest survey for 2009, with around 76% recall, followed by the hologram (55%), security thread (15%) and type of paper (14%). The see-through register received 9% recognition and tactility 8%. Surprisingly, the lowest rankings were scored by optically variable ink  (3%) and iridescent stripe (2%). 7% of the respondents didn’t know of any of the security features.

Selecting features that engage the public and communicating these is an issue in itself. But getting them to check their notes in the first place appears to be an even bigger one. Members of the Dutch public receive on average 1-2 banknotes a day and the odds of them receiving a counterfeit, says de Heij, are less than winning the lottery. Hence most people don’t bother checking them. Counterfeiters, in turn, do the bare minimum required to get their notes passed – focusing on the key features that the public are likely to look at. The result is counterfeits that are generally of a poor quality. This leads to issuing authorities reassuring the public about the low quality of counterfeiters which renders them, in turn, even less inclined to check their notes. 

As well as examining the different studies and methodologies for evaluating features, communicating these, testing opinion and analyzing counterfeits, de Heij came up with a number of recommendations for the deployment of features.

Notes, he said, should contain a maximum of six public features (three active and three sleepers, the latter activated one at a time when preset counterfeiting thresholds have been reached) and no more than 20 overall. ‘Nested’ features (containing several different elements) should be avoided as these can confuse. So should multi-level features (ie those combining overt, covert, machine-read and/or forensic elements), as these tend to be ‘sub-optimised’ for the different user groups. Optically variable features based on movement or motion, meanwhile, are more effective in terms of public recognition than those based on colour.

Undoubtedly, his findings – although relating to banknotes - will find resonance amongst other issuers of secure documents and products – the challenge being to find features that with simple effects that can be validated quickly and accurately and, above all, are likely to engage the attention of the various user groups – be these consumers, retailers or distributors – for whom they are intended. With respect to the latter point, De Heij’s presentation demonstrated that this is perhaps the most challenging issue of all. 

A copy of this, and the other presentations at Optical Document security, are available for €26 each, of €220 for all, from the event website: