Technical info

Envelope terminology

Format series

Format series are the basic tools for standardization (normalization) of production and products. In paper industry and polygraphical field, the format series A, B, C and E are used. The basic series A is used for final documents – most frequently A4 or A5 sizes, A3 respectively. The sizes in series B and C are larger and are used in cases the final product in A series reaches its final adjustment (trimming, folding etc.) or should enable inserting the product of A4 size. These formats are common in polygraphy and envelope production. For envelope production, series B and C, highlighted in chart above, are predominantly used, or their combination (e.g. C5/6). Envelope DL with size 220 x 110 mm is completely outstanding from other format series. The E format series is rarely used in the Czech Republic.

Production modes

Envelopes are manufactured on envelope machines from paper reels of corresponding width or pre-cut blanks of unfolded envelope shape.

• Production from rolls

  Used for mass production of standard envelopes with various adhesive types, with or without inside print, and with flexographic print in one to four colors (simple logo print and address).

• Production from blanks

  Used for production of small series of envelopes with special requirements (atypical format, envelopes from pre-printed sheets, color paper, special kinds of paper etc.).

Envelope and pockets production material

Paper with specific characteristics, such as strength, flatness, shade stability, stiffness etc. Standard envelopes are produced in substance 80 g/m², paper pockets in 100 g/m².

Flaps

Self flap with glue to seal the envelope. It can be variously shaped.

	straight Suitable for all sealing types: usual length 25 – 40 mm. Gummed usable for automatic filling with some envelope line.
	diamond Only gummed.
	ready-made Only gummed.
	Teide 2000 Only gummed, primarily for automatic filling.
	EURO flap Only gummed, primarily for automatic filling.
	trapeze Only gummed, primarily for automatic filling.
	circular Only gummed. For lengths 35-45mm suitable for automatic filling.

Flap sealing adhesive

The following types of sealing adhesive are used:

• Gummed

  Adhesive after moistening. The flap is used in all envelopes for automatic filling.

• Self-seal

  On both parts gum (double-flap self adhesive envelopes). Sealed when pressed together.

• Strip-seal

  A strip of Silicon paper, peeled before sealing, covers the flap.

Envelope and pockets window

Windows on standard envelope formats are made with rounded corners following the ČSN or DIN norms, details in chart below. Distance between the window and side seam must be at least 12mm. Window material is normally transparent matt foil. Window location or size, not included in chart below, are non-standard and can be produced on request.

ČSN: Czech Republic, Slovakia

DIN: Germany

Envelope design

• Black mark - "M" style

  Three black thick lines on envelope bottom right or under the window are standard only on c5/6 envelopes. Used for post services – post sorting machines which identify address according to the black mark. The style with black mark is called M (e.g. C5/6M).

• Address lines - "R" style (handwriting)

  Used rarely, available only on C6 envelopes. They consist of address line, black mark preceded by marked postal code spaces. The style is called R (e.g. C6R).