Large proportions of envelopes are manufactured with windows, and the specifications for them can be confusing. Measurements are always taken with the flaps at the top.
Types of envelope Window Film
Standard Window Film
Standard window film is around 22 micron and is approved as suitable for Royal Mail OCR reading.
Manufactured from Cornstarch - Cornstarch window film is used throughout our Purely Environmental Evolve Recycled Range to ensure it is both recycled and recyclable.
Window envelopes from our Premium Business, Premium Office, Premium Pure and Premium Postfast ranges are produced with a 50 micron window film making them guaranteed to withstand the heat of both colour and mono laser printers and digital machines.
We also stock a collection of envelopes under our Purely Everyday range with windows on the reverse side of the envelope, these are especially designed to leave the face area of the envelope completely free for full face printing.
Bespoke Envelope Windows
Bespoke envelopes can be produced with any shape window, including circular. Some promotional mailshots can have multi-windows or windows in the reverse of the envelope.
Printing the inside of the envelope or interior opaque, as it is known, is designed to enhance the security of the contents. This is almost exclusively restricted to white envelopes.
An interior opaque can also be used to reveal a message through the window once the contents have been removed. We use this in both our Purely Environmental Recycled and our Purely Environmental FSC ranges to reinforce their environmental credentials.
Most interior opaques are printed in shades of blue or grey during manufacture. However, on special bespoke orders if the quantity is large enough, customers can have their own design opaque or specified Pantone colour. Some choose to incorporate names, logos or messages in the throat of the envelope which is referred to as a lozenge.
Our blueprint opaque is the ‘mountain peak’ design, printed in Pantone 292 and consistent across the complete range. This opaque has proved very popular, so much so, some have tried to imitate it. We also offer a few select lines with a grey opaque.