A basic protective graphical element is a guilloche pattern. It consists of a series of continuous, interlaced fine lines combined into various geometric shapes usually frames, lines or rosettes. Another protective element is background printing, covering the majority area and containing patterns of fine lines making the document difficult to reproduce with standard techniques.
Printing of these elements is usually combined with rainbow colouring -also called split duct printing. This colouring process used in offset printing is used to protect security documents against colour separation or copying, by subtly merging colours into each other resulting in a gradual colour change. Letters or numbers in the font size of 1 point is considered to be a microprint.
Microprint is used as a security element of background printing. It is not discernible with the naked eye and it cannot be reproduced with basic methods.