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ENVELOPE DICTIONARY

Like most industries, the envelope industry has it's own technical terms or jargon.
The following list summarises many of the terms and definitions used;

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BangtailA special type of wallet incorporating a perforated flap and an extension from the throat e.g. a Barclaycard envelope.Click here for more information
This is a special style of wallet envelope with a perforated coupon attached which can be detached for use as a reply form, typically used for remittance, subscription renewal or direct mail envelopes.

These envelopes make retrieving and recording information very easy.

Usually, promotional material is printed on the perforated reply slip flap, which can then be filled in and returned inside the envelope once completed.

Bangtail envelopes are widely used by charities and fundraising organizations to facilitate the collection of donations, where the design can be useful for protecting the privacy of the donor’s details.

There are two styles of Bangtail envelopes:

1. The bangtail ‘flap’ has its reply slip attached to the flap of the envelope.

2. The bangtail ‘back’ has a reply slip attached to the back panel of the envelope.

BankerAn envelope with a diamond shape or V-flap opening on the long edge, also known as invitation envelopes.Click here for more information
A banker is a classic envelope style that can be recognised by its diamond or v-shaped flap opening on its longest side.

These can also be known as greeting card or invitation envelopes, due to their tradition of being used in the greeting card industry for sending personal notes and cards.

The origin of the use of the diamond shape for envelopes is not certain, but could perhaps have been used as a handy alternative to simply wrapping a sheet of paper around a central rectangular area such as a folded letter or an invitation. With this style, you will be left with an arrangement of four diamond shapes flaps on the reverse side, which only need to be sealed to provide a tidy, paper-efficient way of producing an envelope.

Today, banker envelopes are very commonly used.

BasketweaveA manilla paper with a weave effect finish, traditionally used for heavy weight papers, typically in 115gsm.Click here for more information
Basket weave is a simple type of textile pattern which resembles basketwork, forming a criss-cross pattern.

Basket weave envelopes feature a distinctive weave effect finish, traditionally used for heavyweight 115gsm manilla papers.

Strong and secure, these envelopes are suitable for all general purpose mailings where durability is important.

This crisp, quality paper has tear-resistant qualities which withstand even the roughest handling and ensures protection for all contents. All this makes these envelopes the ideal choice for those more bulky documents and catalogues.

Our Purely Everyday range features a number of basket weave envelopes.

Did you know, using envelopes with a textured paper will lend a certain quality and charm to your mailings? Explore our Premium Business range for more classic textures, from a timeless laid, to the beautiful wove and flawless digital smooth options.

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BespokeCustomised envelopes made to customer specifications, not from stock.Click here for more information
Made for a particular customer or user, bespoke envelopes are made to exact specifications. These are generally for a specific purpose or requirement: a need that cannot be met with a standard stock item.

Our Personalisation Service can produce any size and shape of envelopes or packaging solution, from almost any kind of material, printed or unprinted, according to your specifications.

Working closely with you, we will meet your every requirement and create unique, tailor-made envelope and packaging solutions to elevate your communications, ensuring your messages resonate with the consumer every time.

Our team are happy to give you all the support you need to ensure your creative vision hits the mark, and will collaborate with you to develop an idea from the start, nurturing it through to a reality utilising the best materials and techniques available.

Learn more about our bespoke capabilities in our Personalisation section, and get in touch today to design the perfect envelope for you!

BiodegradableRecyclable and able to disintegrate naturally over time, these will not contribute to landfill. Click here for more information
In recent years there has been a growing demand for biodegradable and recyclable packaging products, due to the rising issue of overpacking and plastic pollution.

Our new VITA plastic free ecommerce packaging range aims to address these issues by providing paper based, environmentally friendly alternatives to all the traditional plastic packaging products.

Our Purely Environmental range also offers a variety of different recycled envelope ranges including FSC envelopes, Flora, Nature First and Evolve recycled envelopes, making us the obvious choice for the environmentally conscious business!

But what do these terms actually mean?

Biodegradable substances are capable of being decomposed by bacteria or other living organisms, whilst recyclable materials have the ability to be processed and used again: both having a positive effect on the environment by avoiding the building up of waste.

Biodegradable and recyclable packaging tends to be constructed from a set of polymers that are derived from renewable raw materials like starch e.g. corn, potato, and tapioca, cellulose, soy protein and lactic acid, which are non-hazardous in production and decompose back into carbon dioxide, water or biomass when disposed of correctly.

For more information on our biodegradable and recyclable products, please speak to our sales team on 01935 477 555 or email [email protected]

Blank FedEnvelopes manufactured from flat sheets, punched out and made up.Click here for more information
Blank fed is an envelope manufacturing term that refers to one of the main types of envelope converting presses.

Blank fed envelopes are manufactured from large flat sheets of paper which are punched out with a die cutter in the shape of an unconverted envelopes, producing a blank. A blank converting press then accepts the die-cut paper and it is folded and glued during the manufacturing process to form the finished envelope.

If blank fed envelopes require over printing, this is usually carried out prior to cutting out the envelope blank. Similarly, if a window is required, this can be carried out as a separate operation once the envelope blanks have been cut and prior to the folding and assembling of the finished product.

Board BackAn envelope style that is generally a pocket, made with a cardboard back & paper front. Typically, 120gsm paper and 1000 micron board is used. Click here for more information
Need extra protection for fragile contents? With their rigid cardboard back and paper front, board back envelopes offer the perfect solution.

Generally coming in a pocket format, these envelopes would usually utilise a 120gsm paper and 1000 micron backing board, and are the ideal choice for preventing valuable or fragile documents from getting damaged, creased or bent in the post.

Examples of contents that require a board back envelope include certificates, brochures and legal documents.

Our board back envelope collection boasts an excellent range of heavy duty products, available in a combination of white, grey or manilla. Made using a durable backing board and heavyweight face paper, these will guarantee maximum protection when posting bendable items. Also ultra secure, these products feature a peel and seal closure: the most secure method of sealing, and the option of a ‘do not bend’ precaution printed on the face.

BREShort for Business Reply Envelope, these are pre-printed with the sender’s return address and a prepaid postage. Also known as 'prepaid envelopes'.Click here for more information
A BRE, or Business Reply Envelope, is an envelope printed with the sender’s return address and a prepaid postage which has already been paid by the sender. These envelopes can also be known as a ‘prepaid envelope’ by Royal Mail.

BREs are used by businesses to encourage customers to reply to them without the customer having to pay the Royal Mail's postage cost themselves.

These envelopes are normally an undersized DL (105x216mm or 102x216mm) or an undersized C5 (155x220mm) size.

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Card EnvelopeA protective envelope made completely from card. Sometimes this may also refer to an envelope that is used to send a greetings card in, such as our Invitation envelopes.Click here for more information
Card envelopes are just that: an envelope manufactured from card!

Made entirely from a hardwearing card, these provide a rigid and hardwearing packaging solution that will guarantee extra protection and support for all contents, eliminating any risk of creasing or bending.

Explore our Premium Optima Envelopes for a superb range of heavy weight card envelopes spanning 7 different sizes. Coming in a pristine bright white shade, these are the ultimate in envelope quality.

Sometimes, the term ‘card envelope’ may refer to an envelope that you would send a greetings card in: in this case this would refer to our invitation envelopes.

Colour WashA printing technique used to give a tinted or coloured effect. This often relates to internal opaques.Click here for more information
Colour wash is a printing technique which can be used on the inside or outside of an envelope. This is where a solid colour is printed bleeding off all sides in order to give an overall tinted or coloured effect.

The term ‘colour wash’ will often relate to the internal opaque of an envelope. our Envelope Insights section for more information.

A colour wash can be achieved by mixing an ink with another liquid, which is then used to do an all over wash on an envelope, creating a solid colour.

This would normally be applied using flexographic printing.

We offer a number of products with a colour wash interior within our Purely Everyday range.

Corn Starch Window FilmNormal window films will not biodegrade, however corn starch window film biodegrades in 30 days.Click here for more information
A normal window film will not biodegrade. A biodegradable window film, however, can be manufactured from corn starch and will biodegrade in 30 days.

Corn starch window film is used throughout our Purely Environmental Evolve Recycled Range to ensure it is both recycled and recyclable.

A matt film with a normal brightness, our corn starch film is available in a 29 micron thickness. Made from annually renewable plant resources which will biodegrade in 30 days, it has an excellent moisture transmission rate, high natural dyne level, excellent scratch resistance and high transparency to UV light. Besides all this, it offers an environmentally friendly alternative to plastic window films, and will not affect the paper recycling process!

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Diamond Press EnvelopesA make of envelope printing press, good for larger envelope sizes such as C3, as well as board backs and gussets.Click here for more information
Diamond Press is an American make of envelope printing press which is great for larger envelope sizes such as C3, as well as board back and gusset styles.

With a variety of envelope manufacturing machinery to produce large-run and short-run printing, they have the most modern envelope manufacturing capabilities and a dynamic range of envelope printing and folding equipment which enables them to produce any type and size of envelope.

Diamond offer versatile, modernized high-speed and blank fed production that prints up to 8 colours, for superior manufacturing and accurate registration at a cost saving to the client.

Drilled HolesSmall holes which are typically drilled into internal mail transit pockets, used to check for inserts. Click here for more information
Paper drilling is a technique that drills a series of small round holes in large quantities of paper.

This technique can be used to put holes through envelopes to serve for storage and filing purposes, or so that the recipient can confirm that all contents have been removed.

Drilled holes are most common in internal mail transit pockets, where they are used to check for inserts.

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FlexoA printing technique carried out during manufacture or printing in-line for large quantities which are not up to the quality of litho printing.Click here for more information
Flexography, which is usually abbreviated to ‘flexo’, is a printing technique using water-based inks that is carried out during manufacture or printing in-line.

Flexo printing was invented in Liverpool in the year 1890, when the first press was built by Bibby, Baron and Sons. By the early 1900s other European presses using rubber printing plates and aniline oil-based ink had been developed.

This method of printing is used for large quantities of envelopes which are not up to the quality of litho printing. Despite the fact that quality is traditionally lower that litho printing, this is the most cost effective method for printing larger runs.

Utilising a flexible rubber or photopolymer relief plate that wraps around a cylinder, usually as part of the envelope production machine, flexo printing is essentially a modern version of letterpress and can print onto almost any type of substrate including plastic, metallic films and cellophane, as well as paper.

Here at Blake, we use flexo printing for a variety of purposes.

FSCStanding for Forestry Stewardship Council, FSC credentials give full traceability on raw materials such as pulp or paper. Click here for more information
FSC stands for Forestry Stewardship Council. This is an international non-profit, multi-stakeholder organization established in 1993 to promote responsible management of the world’s forests by setting standards on forest products, and certifying and labelling them as eco-friendly. This gives full traceability on raw materials such as pulp and paper.

FSC® certification has become one of the most recognisable environmental credentials of the day. Our FSC® envelope range is made from FSC® certified paper, and each envelope clearly promotes the logo and credentials through the window of the envelope.

At Blake, we endeavour to only source and market products that are manufactured by companies with specified environmental policies, from sustainable, well-managed forest sources.

We continue to increase our range of environmentally friendly envelopes products, which now totals more than 67% of our product range, making it the largest range available in the UK for next day delivery!

With our expansive array of FSC® certified products, we are supporting the responsible use of forest resources.

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GlassineA paper based material used for envelope windows and some wage and photographic pockets.Click here for more information
Glassine is a paper based material which can be used for envelope windows.

A smooth, glossy paper that is air, water and grease resistant, glassine is usually available in densities between 50–90 g/m². It is translucent unless dyes are added to colour it or make it opaque.

A unique grade of paper, it has many desirable properties and benefits, making it a popular choice. It is environmentally friendly, coming from 100% sustainability-managed forests and is also 100% recyclable and biodegradable.

This type of window film is often used in our bespoke envelopes.

GSM / GrammageA measurement which determines the weight of paper, measured in g/m2.Click here for more information
GSM stands for grams per square metre. This measurement determines the weight of the paper, and is measured in g/m2.

Different weight papers are used for different purposes, but usually the higher the grammage and the thicker the paper is, the better quality it is. Our envelopes and packaging products range from 80-200gsm.

See below for all the standard paper grammages and what these are used for:

80-100gsm - Copy Paper, Printer Paper

120-170gsm - Parchment Paper, Premium Printer Paper, Card Inserts, Luxury Paper Pads, Background Papers, Foiled Papers, Envelopes

200-250gsm - Average Weight Card, Stamping Card, Embossed Card, Mirror Card, Printing Card, Decoupage Sheets

260-290gsm - Pearlescent Card, Topper Sheets, Designer Card, Kraft Card, Card Blanks

300-350gsm - Heavyweight Card, Luxury Card Inserts, Hammered Card, Centura Pearl Card, Luxury Designer Card, Luxury Topper Sheets, Decoupage Sheets

GummedThis refers to the envelope sealing method that requires moistening to seal. This is the most common type of sealing.Click here for more information
The term ‘gummed’ refers to an envelope sealing type.

Gummed envelopes have a strip of water soluble gum adhesive which requires moistening to seal. This gum is usually made from a blend of synthetic resin and dextrin, so is therefore biodegradable.

This is the most common sealing method and is always used for mailing envelopes as only gummed envelopes are suitable for automatic machine inserting, where the sealing can be performed automatically by the mailing machine.

If stored in the correct conditions, gummed envelopes should last for a number of years.

Many of our Purely Everyday envelopes are gummed.

Other sealing types include self-seal and peel and seal.

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GussetAn envelope with an expandable side seam, these can have a block bottom or V- bottom.Click here for more information
A gusset envelope has an expandable side seam. These are normally a pocket envelope, and can have a block bottom or V- bottom. All our stock is V-bottom as this style is suitable for over printing.

Gusset envelopes provide a spacious and convenient approach to sending bulky documents such as catalogues and reports.

Now becoming increasingly popular for ecommerce fulfilment, these enable businesses to reduce packaging waste whilst ensuring their produce arrives safely and with minimal carriage cost.

Our gusset envelope collection spans over 52 different products, from coloured and board back options, to tear resistant and recycled envelopes, and is sure to have the perfect choice for you however specific your requirements!

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Halm Jet PressA make of envelope printing press most commonly used in the envelope industry.Click here for more information
A make of envelope printing press most commonly used in the industry.

Blake now have 2 Halm EM5000 litho overprinting machines which are equipped with 5 printing units, four colours face and one reverse.

These have the ability to print 4 colour process to the face of the envelope at the same time as printing 1 colour on the reverse, so that there is no need to run a second pass for the all important return address or message.

With its central impression cylinder, the EM5000 machine can hold close registration across a variety of envelopes, giving an outstanding print result. The EM5000s are also equipped with UV drying capabilities allowing for coated papers to be printed.

Hot MeltA form of Peel & Seal adhesive, holt melt is a narrow band of adhesive similar to double sided tape with a heavier gram weight than normal.Click here for more information
Hot melt is a form of peel and seal adhesive featuring a narrow band of adhesive which looks similar to double sided tape adhesive which has a heavier gram weight than normal, giving a long shelf life of 5 years.

Hot melt sealing can also be known as super seal, strip seal or peel and stick.

Hot melt sealed envelopes are the most common option of peel and seal envelopes we stock. Due to their sealing properties, hot melt peel and seal acts as a tamper proof security seal as it is impossible to open the envelope without tearing the flap.

The other form of peel and seal adhesive is cold melt. This method of sealing is similar to self-seal latex, with one band of adhesive which is covered by a large silicone paper strip. Envelopes with cold melt peel and seal normally have a shelf life of 2 years.

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Invitation EnvelopesA gummed envelope with a classic diamond flap, usually used for greetings cards and invitations.Click here for more information
Invitation envelopes are a classic envelope style that can be recognised by their diamond shape or v-shaped flap opening on the longest side.

These can also be known as a banker or greetings card envelope, due to their tradition of being used in the greeting card industry for sending personal noted and cards.

This style of envelope is the perfect choice for any special event.

Explore our select array of invitation envelopes within our Purely Everyday range, encompassing 29 handy sizes!

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Laser Window FilmsA window film of double the thickness to normal film, enabling it to go through laser/digital printers without melting in the machine. Click here for more information
Laser window films have double the thickness of normal film, and has heat resistant qualities, enabling it to go through laser/digital printers without melting in the machine.

It measures 40-50microns as opposed to the standard 22mm.

Window envelopes from our Premium Business, Premium Office, Premium Pure and Premium Postfast ranges are produced with a 50 micron laser window film, making them guaranteed to withstand the heat of both colour and mono laser printers and digital machines.

Other types of window film include a standard film, or a biodegradable option.

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Machinable / Mailing WalletAn envelope for use on an inserting or mailing machine.Click here for more information
A mailing wallet can be defined as envelope for use on an inserting or mailing machine, and can also be referred to as a machinable envelope.

Featuring a signature trapezium flap and a gummed flap for automatic sealing, this style of envelope is required when using folding and inserting equipment. Slightly larger than the standard envelope sizes, mailing envelopes provide the necessary extra space required for the machine to faultlessly insert any contents.

With distinctive features and laser windows, these envelopes support the latest digital print technology and are perfect for processing mail at speed, as designed to run easily and efficiently on all mailing inserting machines with a consistent quality to avoid expensive machine down time.

Browse our extensive range of mailing wallets and uncover the largest range of machine inserting envelopes in the UK, offering all the most popular sizes, from DL to C4, with windows or non-windows, not to mention recycled options…

Matt CoatedEnvelopes made from coated paper designed for full colour overprint.Click here for more information
Matt coated envelopes are made from matt coated paper.

These envelopes are designed for full colour overprint, as their matt finish has a very noticeable effect on the appearance of the printed colour.

The coating on these envelopes keeps much of the ink from being absorbed by the paper, which produces excellent, vibrant colour.

MicronThis is a measurement which describes the thickness of paper in 1000mmClick here for more information
A micron is a measure of paper which describes its thickness: one micron is equivalent to 1/1000 of a millimetre. This is seen as a much more accurate measurement than grammage, as a micron is a measure of distance and not weight.

See below for some of the common paper weights in both microns and grams, along with their traditional uses:

80-100gsm Copy Paper, Printer Paper

120-170gsm Parchment Paper, Premium Printer Paper, Card Inserts, Luxury Paper Pads, Background Papers, Foiled Papers, Envelopes

200-250gsm Average Weight Card, Stamping Card, Embossed Card, Mirror Card, Printing Card, Decoupage Sheets

260-290gsm Pearlescent Card, Topper Sheets, Designer Card, Kraft Card, Card Blanks

300-350gsm Heavyweight Card, Luxury Card Inserts, Hammered Card, Centura Pearl Card, Luxury Designer Card, Luxury Topper Sheets, Decoupage Sheets

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OpaqueA printed design or wash inside an envelope, typically for security purposes.Click here for more information
The opaque is the printed design or wash inside an envelope which is typically for enhancing the security of the contents. This is almost exclusively restricted to white envelopes.

Opaques 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.

Our blueprint opaque is the ‘mountain peak’ design, printed in Pantone 292 and consistent across the complete range. We also offer a few select lines with a grey opaque.

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PantoneA global reference for shades of print colours - each has its own individual number. Also referred to as PMS colour (Pantone Matching System).Click here for more information
Pantone is a worldwide reference for shades of print colours; a system for matching colours, used by many industries including printing, graphic design and paint, to name but a few. This may also be referred to as PMS colour (Pantone Machine System).

Each Pantone colour has its own individual number, allowing these to be recognised across the globe, acting as a colour language for designers, and the definitive language of colour.

At Blake, we use the Pantone reference codes for specifying printing inks.

PDFA method of supplying artwork via email, PDF stands for Portable Document Format.Click here for more information
Providing a method of supplying artwork via email, the Portable Document Format is a file format developed by Adobe which is used to present documents in a way that is independent of application software, hardware, and operating systems.

All the artwork for our envelopes would be transferred using a PDF file.

PEFCStanding for the Programme for the Endorsement of Forest Certification, this gives full product traceability.Click here for more information
PEFC stands for the Programme for the Endorsement of Forest Certification Schemes, which gives full product traceability.

The Programme for the Endorsement of Forest Certification is an international, non-profit, non-governmental organization which promotes sustainable forest management through independent third party certification. It is considered the certification system of choice for small forest owners.

At Blake, we endeavour to only source and market products that are manufactured by companies with specified environmental policies, from sustainable, well-managed forest sources.

We continue to increase our range of environmentally friendly envelopes products, which now totals more than 67% of our product range, making it the largest range available in the UK for next day delivery.

Many of our Purely Everyday envelopes are PEFC certified.

PerfectingThe term used for litho printing on both sides of an envelope at the same time.Click here for more information
Perfecting is the term used to refer to litho printing on both sides of an envelope simultaneously. With the ability to print the face and reverse of the envelope in a single pass, this makes it a much faster process.

There are two basic configurations of offset perfecting presses:

1. Using a convertible perfector. This features special transfer cylinders which are positioned between successive printing units, which flip the sheets of paper over after leaving the first impression cylinder, enabling the second unit to print on the reverse side. These presses have the advantage of also being able to carry out single-side multi-colour printing but simply adjusting the transfer cylinders so they are prevented from flipping the paper.

2. Using a blanket-to-blanket press. Used primarily in web offset lithography, where the impression cylinder is replaced in one printing unit by a second blanket cylinder directly beneath the first. As the sheet or paper web passes between the two blankets, both sides can be printed on to simultaneously.

PIPThis is an abbreviation for 'Pricing in Proportion' - the way Royal Mail charge for the posting of mail.Click here for more information
'Pricing in Proportion' is how Royal Mail now charge for posting of mail, based primarily on the weight and size of the envelope, depending on whether it is a small letter, large letter or parcel. 1st Class or 2nd Class.
PocketAn envelope with its opening on the short side.Click here for more information
A pocket is a type of envelope with the opening on the short side. The opposite of this would be an envelope with the opening on the long side, which is known as a wallet.

The 3 most common types of envelopes are pockets, bankers and wallets.

When choosing the right envelope for your needs, decide where you would like the opening to be placed as there are different options available to you. Wallet and banker envelopes have the opening flap placed on the long edge of the envelope which is what defines the envelope as a wallet or a banker.

Wallet envelopes would normally have a trapezium shaped flap which is suitable for automatic mailing machines and can come in straight or slightly curved variations.

Banker envelopes can be identified by their triangular flap which is traditionally used in the greeting card industry and for personal use note/letter paper and cards. They can often be referred to Greeting Card or Invitation Envelopes, which you may have heard of.

PPIThis stands for Postage Paid Impression e.g. 1st Class or Mailsort.Click here for more information
PPI stands for Postage Paid Impression e.g. 1st Class or Mailsort.

Offering a convenient alternative to stamps or franking machines if you're sending large volumes of mail in the UK or internationally, Printed Postage Impressions (PPIs) save both time and money by enabling the postage to be printed directly onto labels or envelopes.

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RecycledRecycled envelopes are made from post consumer waste.Click here for more information
The term recycled refers to something that has been used before and then put through a process so that it can form a new product. This process helps protect the environment, reducing waste and pollution.

Our recycled envelopes are made from post-consumer waste. Covering a wide range of products, from our FSC envelopes, to the Flora, Nature First and Evolve options, providing you with everything you need to act responsibly and do you bit for the environment!

Our FSC range contains envelopes with some of the most recognised environmental credentials of the day, which are manufactured from fully certified paper.

Our Flora Recycled envelopes are a classic example of a recycled envelope, with a signature off white shade giving clear proof of their recycled nature, and a green opaque to further emphasise the environmental message.

Our Nature First envelopes are 100% recycled as well as FSC certified, and boast a bright white shade unusual in recycled envelopes, making them the obvious choice!

Evolve is a name well known in environmental circles. Stocked exclusively by Blake across Europe, our Evolve recycled envelopes are widely respected.

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Reel FedAn envelope manufactured from reels of paper. These are the most cost effective of all our envelopes.Click here for more information
The high speed manufacture of envelopes from reels of paper gives one of the most cost effective and consistent means of producing envelopes, ideally suited for higher volume direct mail, doordrop and business reply envelopes.

Winkler and Dunnebier are the main producer on envelope manufacturing machinery, and manufacture both reel fed envelope machines for envelope production.

A big competitor to W & D is F L Smithe who are an old established envelope machine manufacturer from the USA. Their RA800 and RA600 machines can also be supplied in reel fed and give speeds up to 800 envelopes per minute.

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Security SlitsSmall slits in the flap of some self seal envelopes, offering tamper proof security.Click here for more information
On the flap of certain self-seal envelopes, you will sometimes find security slits.

These small cuts are designed as 'tear points' for tamper proof security, and will cause the flap of the envelope to rip if the seal has been tampered with, ensuring greater safety for your mail.

Self SealThis refers to the sealing method where the envelopes two flaps are pressed together to form an instant bond. Click here for more information
Self-seal is a sealing method where the two flaps are pressed together to form an instant bond.

Each of these flaps has its own strip of latex which, with contact to the other strip, will instantly and securely fasten the envelope flap. This method of sealing can also be known as dri-seal, press-seal and fast-seal.

The latex on self-seal envelopes is derived from rubber and ammonium substrate, and can therefore be classed as a natural product.

This normally only has a guaranteed shelf life of twelve months from date of manufacture but, if stored in the correct conditions, this may extend.

For optimum shelf life, self-seal envelopes must be kept in an equilibrium temperature. Here at Blake, we carefully control the temperatures of our warehouses throughout the year, providing controlled heating in the winter and cooling in the summer to maintain the ideal temperature for these products.

Security slits can sometimes be found on the flap of self-seal envelopes for security reasons. These will cause the flap to rip if the seal has been tampered with.

Set-OffThe term used to describe where the print on one envelope marks another.Click here for more information
This is where the print on one envelope marks on another: a problem that can occur with most types of printing.

Unless time and care is taken to avoid it, the occurrence of set-off is very likely to occur where the ink coverage is heavy and/or strong colours are used.

However, there are several ways this can be eliminated or the effects can be minimised, such as running the print more slowly, using an anti set-off spray or UV driers, which can avoid the issue by ensuring the envelope is dry when going onto the feed table. For more information on this, see our UV Dryer section.

In offset printing, this term also refers to the unwanted transfer of ink to rollers and friction points throughout the printing press. This can be cause by the build-up of ink that isn’t properly dried of set over time, which can result on marking on the finished product.

In some cases, certain offset printing applications will add moisture back into the paper after it has been dried with an offset heat set drier, which, when it doesn’t have enough hardness, can end up breaking down the calcium carbonate in the paper which will lead to a build up and set off on the following jobs.

Shelf LifeThe term to describe the useable life of an envelope, which is generally applied to Self Seal and Peel & Seal envelopes.Click here for more information
The shelf life is the useable life of an envelope, or the length of time it may be stored without becoming unfit for use, consumption, or sale.

It is generally applied to Self Seal and Peel & Seal envelopes.

This can vary a lot, and often depends on the sealing type used. Here we share the different shelf lives of each sealing type we stock:

Gummed envelopes have a shelf life of a number of years, provided they are stored in the correct conditions.

Self Seal envelopes, on the other hand, have a strip of latex on each flap which is pressed together to form an instant bond. The latex on self-seal envelopes normally only has a guaranteed shelf life of twelve months from date of manufacture. If stored in the correct conditions, however, and with an equilibrium of temperature, this may extend.

Peel & Seal envelopes have a tear off tape revealing a strip of latex, which is pressed down to form an instant bond. There are 2 types of peel & seal sealing:

Cold melt Peel & Seal: Similar to self-seal latex, this has one band of adhesive which is covered by a large silicone paper strip. Envelopes with cold melt peel and seal normally have a shelf life of 2 years and;

Hot melt Peel & Seal: The most common option of peel and seal envelopes we stock, these have a narrow band of adhesive which is of a heavier gram weight than normal peel and seal and looks similar to double sided tape, guaranteeing up to 5 years shelf life.

ShoulderThis feature is located on the top of the side flaps of a wallet envelope. Click here for more information
An envelope shoulder is situated at the top of the side flaps at the opening of a wallet style envelope, and can be a critical design aspect when using inserting machines.
Side SeamsThe seams at the sides of a mailing wallet, these can either be internal or external to suit the requirements of individual mailing machines.Click here for more information
These are the seams at the sides of a mailing wallet, which can be either outside or inside to suit individual requirements.

Mailing houses usually prefer outside seams as they don’t catch on mailing machines, whilst printers may prefer inside seams for printing on the envelope reverse.

Envelope seams are typically permanently sealed for durability.

With mailing envelopes, the outside seams can be folded over the back flap: a technique not commonly requested in envelope manufacture but required by some insertion machines. Normally, the side seams are folded inside or under the back flap of the envelope in order to be as inconspicuous as possible.

Side seams can provide a large area for printing on the back of an envelopes, as seen in reverse face, collection and booklet style envelopes.

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ThroatThe gap between the score line and the back flap of a wallet envelope, this can be a critical design aspect for inserting machines.Click here for more information
The throat of an envelope is seen at the opening at the top of an envelopes, and can be defined as the gap between the top fold score line and the top of the back flap of a wallet, forming the opening via which all contents are inserted.

The size of the throat is measured form the top edge of the bottom flap to the fold line of the seal flap.

An envelope throat can be a critical design aspect for inserting machines, allowing the machine to insert contents into the envelope.

A tapered seal flap and throat contribute to better performance in sealing and automatic inserting applications, and the depth of the throat can be critical in influencing this.

Thumb CutTypically a semi-circular shape cut from a topless pocket or wallet, allowing access to contents inside.Click here for more information
A thumb cut is a shape cut through the back, front, or both sides of a topless pocket or wallet, normally in the shape of a semi-circle.

Thumb cut envelopes have an open end: a handy feature allows for quick and easy access or removal of the contents inside.

These envelopes are designed to hold insurance policies, wills, contracts and other legal documents or, in other circumstances, can often be used for tickets or as negative preservers.

ToplessA pocket or wallet envelope without a flap.Click here for more information
A pocket or wallet envelope style without a flap.

Topless envelopes offer a pleasant change from the norm and can give a distinct luxurious look and feel.

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UV DryerA special piece of equipment fitted to the back of an envelope press, enabling substrates such as matt coated envelopes to be printed without risk of set-off.Click here for more information
Fitted to the back of the envelope press, a UV dryer enables substrates such as matt coated envelopes to be printed without risk of set-off.

Set off is where the print on one envelope marks on another; a problem that can occur with most types of printing. For more information on this, see Set Off.

UV dryers can be used whenever is need of curing and drying inks where UV inks are in use, polymerising images onto screen-printed products as a part of the screen printing process. Printing with UV curable inks provides the ability to print on a very expansive variety of substrates, from paper and canvas to plastic, glass, metal and many other materials.

There are many advantages to UV drying inks. Perhaps the biggest of these is the lack of solvent fumes, which can contribute to air pollution and affect the health of those around. Not only this, but UV dryers also allow for instant drying of ink, which means that the product can be ready to continue working on immediately after being printed. Producing an excellent quality image, the screen printing process allows for a high level of detail, besides being a very clean, low maintenance printing method, therefore allowing for a higher level of production. As the inks that are used in this process don’t include a solvent that is evaporated, they have very high colourant and, sitting on the surface of the material rather than being absorbed, they give an intense colour quality.

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W & DW&D stands for Winkler+Dünnebier, which is a world renowned make of envelope printing presses.Click here for more information
W&D, or Winkler+Dünnebier, is a make of envelope printing presses known worldwide for its outstanding technical and expert know-how in the area of mechanical engineering.

Their wide ranging product portfolio is designed to meet changing customer needs.

With their innovative solutions and high-quality technologies, W&D are internationally synonymous for precision, speed and reliability.

W & D 102A reel fed machine specifically used for producing gummed wallet envelopes up to an oversize C5 size.Click here for more information
The W &D 102 is a reel fed machine which is specifically used for producing gummed wallet envelopes up to an oversize C5 size.

It has been completely engineered with servo-technology to be the ideal replacement option for envelope manufacturers committed to improving the productivity and profitability of their high-volume production.

The W+D 102 RE is a productive fast-change-over, high-volume production system for stationery, transactional and direct mail envelopes.

W & D 212/214The 'Rolls Royce' of envelope presses, these machines are ideal for solid blocks of printed colour.Click here for more information
The 'Rolls Royce' of envelope presses, the W & D 212 and 214 are very costly, but well-built with a heavy roller power which is ideal for solid blocks of printed colour.

The 212 is a two colour machine whilst the 214 prints four colours.

W & D 249An envelope press specifically for the production of larger format pocket envelopes, particularly C4 size.Click here for more information
A 3 colour pocket envelope machine without a window station, the W&D 249 does feature a Peel & Seal station, 3 colours flexo and 3 doctor blade.
WalletA envelope with its opening on the long edge.Click here for more information
An envelope with the opening on the long edge, the wallet envelope often has a trapezium shaped flap which is suitable for automatic mailing machines, but also comes in straight variations.

These envelopes are commonly used in all applications.

The 3 most common types of envelopes are pockets, bankers and wallets.

When choosing the right envelope for your needs, decide where you would like the opening to be placed as there are different options available to you.

Wallet and banker envelopes have the opening flap placed on the long edge of the envelope, and a banker envelope’s flap is a triangular shape, which is traditionally used in the greeting card industry and for personal use note/letter paper and cards. They can often be referred to Greeting Card or Invitation Envelopes.

On the other hand, pocket envelopes have their opening flap positioned on the short edge, which is what defines the envelope as a pocket.

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