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About the Envelopes

Sealing types

There are three main types of sealing envelopes:

  • wet sealing (NK) sealing is triggered off by prior lubrication, which means that in order for the surfaces to be stuck together, all you need to do is to moisten the glue layer on the flap. If stored properly, this type of envelopes is characterised by unlimited life.
  • self-sealing (SK) - sealing based on latex. Both on the opening flap and the counter-flap there is a layer of glue. In order for the surfaces to be sealed, they must be pressed together. It is therefore particularly easy to seal manually. However, depending on storage, envelope life is restricted to one year.
  • self-sealing with a protective strip (HK) - this type of sealing is carried out by removing the strip protecting the glue layer, folding the flap, and pressing the envelope onto the flap. In this way it is tightly closed. Fast, secure, clean, practical, and comfortable. The main advantage of that the protective strip has over wet sealing or self-sealing is that it makes storage much easier, as the strip prevents the glue layer from sticking to envelopes stored beneath. In addition, this type of envelopes makes stuffing easier. Also, it is easier to keep the guarantee period of such envelopes, which is over 5 years. What is more, it is easy to print on this type of envelopes, as the protective strip on the opening flap prevents them from sticking to the printing machine.


In the papermaking industry there are many different sizes of paper sheets available. Examples of standard sizes of paper sheets are A4, A5, A3, A2, A1, A0. Listed below are standard sizes of envelopes:

Format - dimensions

  • C6 - (114 x 162 mm)
  • DL - (110 x 220 mm)
  • C5 - (162 x 229 mm)
  • B5 - (176 x 250 mm)
  • C4 - (229 x 324 mm)
  • B4 - (250 x 353 mm)
  • E4 - (280 x 400 mm)


G.S.M determines the weight of paper in g/m2.
On the basis of this value, the exact weight of a postal matter can be calculated.

In this way it is possible to cut postage costs.

Depending on the type, our envelopes are made of paper with the following G.S.M. values:

  • 75 - 80 g/m2 for C6, DL, C6/C5, B6
  • 90 g/m2 for C5, B5, C4,
  • 100 g/m2 for B4
  • and 130 g/m2 for E4.


As paper can be printed on both sides, it is also possible to print inner sides of envelopes.
wewnêtrzne strony kopert.

It is done for two reasons:

  • first of all to make it impossible for anybody to scan the contents of an envelope 
  • and to read it from the outside.

To prevent this, inner sides of envelopes are simply printed blue or grey.

Other colours are also used.

For the same reason, stripe or digital inner print may also be used.
On the other hand, advertisements may also be printed on the inside of envelopes. For instance, space behind a window can be used in this way.

It is also possible to print advertisements on the whole inner side of an envelope. In this case the envelope must be unfolded completely after it has been opened.


Standard sizes of an envelope window are 45x90 mm.
Its positioning is also standard.

Envelopes of C6, DL and C6/C5 types have a window situated 15 mm from the side edge
and 15 mm from the bottom.

Windows of non-standard sizes are also available

The cost and time required to supply these sizes are agreed individually.


Envelope overprint is produced if and as requested by the customer, using the customer's artwork.

We offer one or multicoloured overprints on all types of envelopes, using offset or flexographic printing.

The cost and time required to supply non-standard overprints are agreed individually.

"NEVADA" envelopes for automatic stuffing

These envelopes are stuffed mechanically.
They are used when substantial amounts of letters need to be sent to customers and envelopes need to be stuffed mechanically.

For automatic stuffing a special type of envelopes with a rounded closing flap is used. A special cut is needed to make it easier for the machine to open and stuff envelopes. Additionally, this type of envelopes is "machine-friendly" in several other aspects, which enables faster and easier stuffing. They have longer, rounded opening flaps and side flaps sealed on the outside.

Envelopes with a layer of air bubble film

This type of envelopes ensures the best protection of the contents to be transported.

It consists of padded air bubble film (polyethylene - recycling) covered with paper. It is produced in ten different sizes (A to K) in brown or white.

Owing to adhesive tape (with a safety strip) it can be easily closed, and its low weight (9-74 g) saves postage costs.