Hologram is a well-known optically variable component used in security printing. A hologram changes properties of reflected light and creates a holographic image which cannot be copied or imitated. Printed on metallised film the holographic image is created from a number of optical layers which capture the light in different angles and through this create an illusion of visual depth or movement. To increase security the holographic image can contain hidden symbols and nanotexts not visible to naked eye. In addition, the individual images can be registered through international organisation IHMA.
The method of application determines the medium which can be:
Hot stamping foil – hologram is applied to a variety of surfaces at high temperature and pressure. The image can have various shapes – stripe, square, circle or shape of a logo.
Self-adhesive foil – once applied it cannot be removed and re-used. Tampering causes the image to scatter.
The type of master
2D hologram – it has only one layer on the image without visual depth.
2D/3D hologram – it is made up of multiple two dimensional layers with holographic images visually place one behind another with visual depth to produce an effect of three-dimensional holographic structure.
Flip-flop hologram – displays two images from different viewing angle. When the viewing angle changes, different images evolve.
Kinetic hologram – similar to flip-flop hologram it contains two images. The images in both layers are the same, but the second image is sequentially shifted to the side so when moved it creates an illusion of movement.
The type of image
Continual (wallpaper) – usually small repeating patterns (with universal pattern). Hot stamping allows application of any part of design where holographic image can be produced to any size using one baseline image. With self-adhesive foil the universal pattern is usually combined with supplementary printing of logos and numbering. This type of hologram tends to be used in small quantities with supplementary printing for personalisation of end products.
Guided – one central pattern size of which determines the overall size of the hologram. The patterns tend to be logos.
All holograms can be personalised by supplementary colour printing of logos, numbering and demetallisation.