Checks make more sense once you know what is being checked. A secure document is built in three stages, each with its own protection, and a forgery has to reproduce all three. In practice it rarely does, and knowing which stage is which tells you where to look first.
Stage one: the substrate
The substrate is the material itself, and it is protected before anything is printed on it.
Paper documents use security paper manufactured without optical brighteners, which is why genuine substrate stays dull under ultraviolet while ordinary paper glows. Built into the material during manufacture are watermarks, security threads and fluorescent fibres. None of these can be added afterwards, which is what makes them valuable.
Polycarbonate cards are built from multiple layers fused under heat and pressure into a single body. That fusion is why a genuine card edge is one uniform section rather than a sandwich.
This stage is the hardest to reproduce because it requires industrial manufacturing rather than printing. That is also why substrate checks carry disproportionate weight: an overall UV glow across the whole surface is one of the more reliable indicators available at first line. Watermarks and threads need transmitted light, see transmitted light.
Stage two: security printing
On the prepared substrate comes the printing that is the same for every copy of that document type.
Intaglio produces a raised, tactile image because the ink sits on the surface in relief. You can feel it, and that tactility is difficult to imitate.
Offset and guilloche create the fine, continuous line work in backgrounds. Genuine line work is continuous. A raster reproduction breaks it into dots, and that difference is visible under magnification but not to the unaided eye.
Microtext is text printed small enough that it requires magnification to read. Genuine microtext remains legible as characters. Reproduced microtext collapses into a grey line.
Optically variable elements, either applied during this stage or as an overlay, change with the viewing angle. See security features that depend on viewing angle.
This stage is where most forgeries are exposed, because desktop reproduction leaves visible traces at magnification. A magnifier with integrated illumination is the practical instrument, since fine print in a dark laminate cannot be read without light on the surface. See 10x, 15x or 30x for choosing magnification.
Stage three: personalisation
Last comes the data unique to the holder: name, date of birth, portrait, document number.
Laser engraving writes the data into a polycarbonate card by carbonising material inside the body. There is no ink, so under magnification the characters show a material change rather than a dot pattern, and the data cannot be lifted off because it is not on the surface.
Dye diffusion and specialist printing are used on other document types, each with a characteristic appearance under magnification.
The portrait should be integrated into the substrate or beneath the overlay, not applied on top of it.
This stage is where alteration rather than counterfeiting happens: taking a genuine document and changing the data or substituting the photograph. Those attacks leave traces in the surrounding material, which is why transmitted light and magnification both matter here.
Where a forgery usually diverges
Ranked by how often it is the weak point:
- Substrate. Ordinary paper or a replacement laminate glows under UV. Fast and reliable to check.
- Print quality. Raster patterns, broken microtext, stepped line work. Needs magnification.
- Optically variable behaviour. A static metallic pattern instead of a device that changes correctly.
- Construction. A card edge showing separate layers instead of a fused section, see ID card or passport.
- Personalisation method. Printed data where engraving is expected.
Note that the order of the inspection sequence in first-line document inspection roughly follows this ranking, which is not a coincidence.
Why this matters for training
Teaching people what a genuine document is made of works better than giving them a list of forgery indicators. Someone who understands that the substrate is manufactured without optical brighteners will recognise an overall glow as significant without needing to memorise it. Someone given only a checklist has to remember, and memory fails under pressure.
That is the reasoning behind starting with genuine documents in hand, as set out in training staff for ID document checks.
Frequently asked questions
Why does genuine document paper not glow under UV?
Because security paper is manufactured without optical brighteners, which are standard in ordinary paper. Deliberate fluorescent elements are then printed on top.
Can a watermark be added to finished paper?
No. It is a density variation created during manufacture, which is what makes it a strong feature.
What is the difference between engraved and printed data?
Engraving changes the material inside the card and shows no dot pattern. Printing deposits ink on a surface and does.
Which stage is easiest to forge?
Personalisation on a genuine document, which is why alteration is common. Reproducing the substrate is the hardest.
Do I need to know all this at first line?
Not in detail, but understanding the three stages makes the checks intuitive rather than a list to memorise.
Equipping a position
For the instruments these checks rely on, see UV flashlights for the substrate stage and the 15x Magnifier DXQ range for the print stage, with an overview on document authentication equipment. To discuss a configuration, request a quote.
