Numbered security seals: marking options

Marking options for numbered security seals

Identifying information is part of the security seals’ raison d’être. Not for nothing: their purpose is to identify and show at all times the key information of the products they accompany. This information could be a number, a barcode or it could be related to the product’s traceability in terms of expiry dates or lots. What customization options are available for numbered security seals? Let’s look at the main ones.

1. Thermal printing for numbered security seals

Within the category of thermal printing of numbered security seals there are several subtypes:

1. Thermal printing

Thermal printing is a form of marking that consists of printing information using heat. This technique can be used on a wide variety of surfaces, including different types of plastics like those used in security seals (polythene, nylon…). Heat is emitted onto an engraving covered with a film of paint in the colour you want to print in.

The advantages of thermal printing for numbered security seals are:

  • The speed of manufacture.
  • Possibility of double-sided printing on the flag of the seal.
  • Wide variety of colours to print.
  • Logos and numbers can be printed, although the limitation of this technique is that it does not allow barcode printing.

2. Laser and thermal printing

This variant solves the limitation of the one described above, since it allows barcode printing by combining techniques such as laser and thermal printing. It permits double-sided printing on any seal colour. There are two variants: marking and deep printing. Double-sided application is possible.

2. Digital thermal printing

Their features are:

  • In this case, the logo bracket is not necessary to apply the marking. The digital technology allows a greater printing resolution.
  • It has greater versatility when it comes to printing: it makes it possible to print logos, barcodes, numbers
  • In addition, once the printing is done, you can write on it with a ballpoint pen (logos and stripes) or with a permanent marker (barcode and stripes).
  • The limitation is that you can only print on one side.

3. Marking numbered seals with injected ink

Injected ink is the best-known printing format. It is traditionally the most used, since it is very reasonably priced, although it has lower resolution than the printing techniques mentioned previously. For example, it allows barcode marking, although they are lower quality to read.

On the other hand, not all seals can accept it and, if you want to add a logo, it needs to be very simple. Otherwise, it is not the most recommendable marking option.

4. Pressure

Poly Lok security sealPressure printing consists of moulding the plastic to press it into the desired numbering. It is a type of marking exclusive for the Poly Lok ring-type security seal, used to seal trucks, containers, warehouses, wagons and also to carry out the quality control of parts.


5. Mould engraving

Pull Grip valve-type security sealThis type of printing carves the plastic so that the information is displayed in relief. It is the most commonly used method to modify button-type or valve seals such as the Pull Grip model.





The customization options for numbered security seals are varied and their choice will depend on aspects such as the conditions of application of the seal (temperature, contact with chemicals), the type of product it accompanies, the sealing time, among other factors. If you have any questions, do not hesitate to contact us: we will be happy to find the solution that best suits your needs.

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