Glossary of packaging terms
We have put these explanations together to introduce you to some of the terms used in our website and documents. We do not represent them as being complete, (they are not) or definitive, or 100% accurate. Please contact us with comments, corrections, and omissions, as we are always keen to refine these pages for everyone's benefit.
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
© Copyright 2010 APL Express Ltd. You must if you want to reproduce this APL Express Glossary in whole or in part.
Acrylic
Sometimes called polyester. A material used for the rope handles of some matt finish carrier bags. The effect is like soft, matt cotton.
Anilox
A cylinder used in a flexographic press. The anilox picks up ink in microscopic pores engraved on the cylinder. This cylinder is midway between the fountain roller in the ink supply and the print blocks which print the image.
Aperture-handle
A plastic carrier bag with a handle formed by punching out an aperture on each side, and then reinforcing the aperture either with a patch welded to the inside, or by giving it an turnover top to provide a double layer of plastic.
Art paper
This paper is bulkier and less dense than kraft, and is therefore usually, and economically, supplied in a heavier grammage than an equivalent kraft, which gives the carrier bag a bulkier feel for similar cost. It does however have a "soggy" rather than "crackly" feel compared with kraft. It can be supplied clay coated one or both sides.
Artwork
The image a customer has supplied from which overprinting will be carried out. APL Express accept artwork as Coreldraw or Adobe Illustrator files, these to be supplied as an EPS file with all fonts turned to outlines. We can also accept high resolution pdf files, and for digital print, 300dpi jpeg files. Artwork can be sent as e-mail attachments or we are happy to download from a specified link site such as You Send It.
A common material for paper bags or counter bags because it is as strong as brown kraft, but is not as utilitarian-looking and takes a much wider range of printed designs. As far as we are aware the "bleaching" is by non chemical processes for environmental reasons.
Often refers to a mixture of HDPE and LDPE used in plastic carrier bags, mixed at the time the film is made (extruded). The result blends the characteristics of each type.
Used for flexographic printing. Usually one block is required per colour for each side of the bag being printed. Also called stereos or "Cyrels", which is the name given by Dupont to their stereo material product. Broadly, the cost of blocks depends on their size, which is dictated by the size of the image to be printed. The blocks are placed on a cylinder which rotates, collecting ink from the anilox, and place the ink on the substrate.
Bromide
Photographic paper with an image on it, from which negatives and then printing plates used to be made. Belongs (almost) to a bygone age, all in 10 years.
Brown kraft
Unbleached kraft. Can be plain, or have a simulated ribbed effect.
CAP tissue
An economy tissue, rather greyish, used for wrap and protection. APL Express CAP tissue is acid free, but generally CAP is not. CAP is OK for packing houseware items, chinaware, shoes, etc., but isn't recommended where a higher level of presentation is required, or appropriate for wrap of delicate items such as silverware, silks, or jewellery. APL offer CAP tissue in two sizes, and a range of MF tissue. For more information, see the APL Express Buyer's Guide to tissue.
Common impression press: a flexographic press used for printing to close registration, and for printing process colours. A large rotating cylinder has a series of smaller inked cylinders rotating against it. The web to be printed is trapped between the large and small cylinders.
Coated
A clay and other material coating on paper, to make it smoother and less absorbent to ink. Produces a smooth finish and better print but can rub off and crack on folds, taking the ink with it. It is therefore usually laminated to protect the ink from cracking.
Co-ex
The process of making material for plastic bags which is say, HDPE on one side, and LDPE on the other. A rope handle carrier bag, for example, can be HDPE (naturally matt and tactile) on the outside, with the puncture resistance and elasticity of LDPE on the inside.
Colour separation
The instructions for a multi colour printing job, or the process of scanning a multicolour image such as a transparency to isolate the 4 process colours of cyan, magenta, yellow, and black.
Corona treatment
The process of treating polyethylene film to give it a "key" to retain flexographic ink.
Cotton
A natural product, made from the cotton plant seed, used for carrier bags and also sometimes for carrier bag rope, or braided tape, handles. For more about cotton, see the APL Express Buyer's Guide to cotton.
Counter bags
Simple paper bags, getting popular again because they are easily and totally recyclable, or they can go into the compost heap. Also called kraft bags, retail bags, fruit bags, or millinery bags. APL Express offer all types of paper, shapes, sizes, colours and designs:
- sulphite white low-cost counter bags for food, gifts and stationery where large quantities are used.
- brown kraft bags, ideal for fresh fruit and other low cost items.
- white kraft paper counter bags in a pre-printed choice of cheerful designs - stripes in pink or blue, starbursts in red & blue, or red & green, and diamonds in gold - all stock designs printed on MG paper which has a sheen.
- quality kraft paper bags in five attractive colours – natural, black, red, green and blue - strong and more up-market, for quality merchandise such as books and higher-value gifts.
Counter bags are still popularly measured in inches, but APL also show the centimetre equivalent.
For more information see the APL Express Buyer's Guide to counter bags.
Cylinder
Printing blocks are placed on a cylinder and each turn of the cylinder will print one image. The bag width or height will therefore dictate the circumference of the cylinder required.
Cyrel
Dupont's name for its material from which printing blocks are made.
Designer
Those who create designs. The world would be poorer without designers. When overprinting carrier bags for a customer, we know that we have to submit a proof of the design to the client to ensure that the artwork supplied will produce the result the client is expecting.
Dispro
The process of compensating for the stretch of a block when placed around a cylinder.
DPI
Dots per Inch. Tones and process print are produced by printing millions of tiny dots of each selected colour. Graduations and photographic effects are therefore possible. DPI refers to the number of dots per line inch, so it is a measure of coarseness or fineness of print. Typical dpi's are 55dpi for a flexo stack press (quite coarse), to 100-130 for a flexo CI press (a little finer). 175dpi is fairly typical for offset litho in carrier bag printing, dependent on paper finish. Please note the metric equivalent is dots per centimetre - expect about 2.5 times less! Beware that inch or centimetre is often unspecified. 'Lines per inch' (LPI) means the same as DPI. Don't confuse DPI with percentage which is the size of the dot.
Duffle
A style of carrier bag with a rope that closes the top and is also attached to the base, so that the bag can be carried over the shoulder by the rope.
Embossing
Creating a raised area, for example over a logo or a selected line of text, to enhance it. Embossing that does not follow a print area is called blind embossing. Debossing is to produce a depressed area to similar effect.
EVA
Eva ethyl vinyl acetate. Added to LDPE freezer bags to maintain their flexibility when cold.
Extruder
A machine which produces polyethylene film. Granules are melted and drawn out in a tube bubble to cool. The more quickly the film is drawn out, the thinner the film, and the bigger the bubble, the wider the film. The tube is often then slit and wound ready for printing.
Film positive
A transparent film acetate with an image in black, with one supplied for each colour. This is used to make a negative prior to block making. History lesson: in April 1996 we wrote: "currently the most popular way of supplying artwork". Very 20th-century - everyone now supplies artwork digitally.
Flexographic
A printing method used for printing polythene and paper, using rotating blocks on cylinders to pick up ink from an anilox and place the ink on the material to be printed. Nearly all polythene is printed this way, and most large-quantity paper carrier bags and flexible packaging.
Fruit bags
See counter bags.
FSC
Forest Stewardship Council, an independent, non-governmental, not-for-profit organisation established to promote the responsible management of the world’s forests. Our website product pages always say when a bag material is FSC certified.
Gauge
A British Imperial Unit of measurement to measure the thickness of polythene film: 1 gauge is one thousandth of an inch. It is giving way to metric. Conversion is easy: 4 gauge = 1 micron. For example, a popular carrier bag gauge of 200 is 50 micron.
Glassine
See greaseproof.
Grain
Paper grain means the direction in which the fibres lay. Paper is often folded with the grain taken into account.
Gravure
A printing method for polythene and paper. A cylinder is laser engraved with microscopic pores which retain ink and, on rotation, place the ink on the material to be printed. The cylinder engraving process is expensive, and suitable for long print runs, but the results are of high quality.
Greaseproof
A grease and fat resistant paper. Also glassine (least resistant), and vegetable parchment (more resistant than glassine, whiter than greaseproof). Greaseproof is most resistant, and is what APL Express offers.
GSM
A measurement of paper weight. Literally, grammes per square meter - if a square meter of paper were weighed, GSM is how many grammes would show on the scales. It is important to remember, if you buy a lot of paper, that it is a measurement of weight, not of thickness or strength. A kraft, which is relatively dense and with long, strong fibres, will be thinner than a bulkier, less dense art paper of the same GSM. The kraft is likely to be stronger, but the art may well exhibit more bulk and be more rigid.
Gusset
A side fold or bottom fold which adds capacity to a carrier bag. In aperture-handle plastic carrier bags, the gusset is the last dimension given eg. 38cm wide x 46cm high + 10cm gusset (ie 5cm in and 5cm out).
HDPE
High density polyethylene. The high density refers to the density of molecule chain in the polyethylene. More "crinkly and crackly" than LDPE, HDPE can be supplied as thin film, eg an 8-18 micron economical counter bag or carrier bag, or as "thick film", a 30-120 micron carrier bag.
Kraft
The word kraft comes from the German 'kraft', which means 'strong', and this is indeed a strong paper, ideal for carrier bags. Normally brown; good for overprinting simple designs in some ink colours, but does not work for all, white ink for example. Kraft is also bleached to produce a white kraft that is ideal for more detailed overprinting. Kraft has good environmental credentials: it is made from 100% recycled content, and is bio-degradable or recyclable. Bleached white kraft no longer uses chlorine but still has environmental disadvantages.
Laminate
A very thin plastic film which can be bonded - laminated - to the surface of paper. It can be gloss or matt. It is applied to a coated paper, to avoid voids, after the paper is printed. Generally 12 micron thick (gloss) or 15micron thick, (matt), and adds about 30 GSM. weight to the finished product. Laminated paper can impede re-cycling, and some kerbside collections do not accept it.
LDPE
Low density polyethylene. The low density refers to the density of molecule chain in the polyethylene. It is more elastic (stretchy) and tears less easily than HDPE. It has a softer feel and is more glossy than HDPE. It can be mixed with HDPE to make a blend.
Litho
Short for offset lithography, a printing method used for printing on paper, based on the principle of oil repelling water on flexible metal plates. It produces a higher quality image than flexographic on paper, and is used for top-of-the-market handmade carrier bags.
LPI
See DPI
Machine finished (MF)
A process of mechanically polishing paper between cylinders.
MF tissue
Machine Finish tissue has a smooth finish obtained during the papermaking process by calendering using a heavy metal cylinder, rather than as a separate manufacturing operation. Machine finish papers may be coated by machine on one or two sides. MF is a step up on the quality ladder from CAP tissue, and is a better tissue in terms of finish and texture, and more likely to be specified as acid free. APL Express stock it in a range of colours, specified acid free and bleed resistant. It is glazed and finished on both sides. For more information, see the APL Express Buyer's Guide to tissue.
Machine glazed (MG)
A process of imparting a shiny surface, usually to kraft paper of 60 GSM upward. It is rougher than machine finished (MF) paper.
MG tissue
Machine glazed tissue is an entry-level mid-range tissue which APL Express do not recommend or offer. Better alternatives are CAP tissue for basic wrapping, and MF tissue for a step up the quality ladder.
Measurements
In Bagspeak, the opening measurement is always stated first, so this will usually be the width. So a polythene carrier bag, the sort with an aperture handle and a "gusset" or pleat in the base, will look like this: 38 x 46+10, which means 38cm wide, 46 cm high, plus a 10 cm gusset, ie 5cm inward and 5 cm back out again. Plastic carrier bags with side gussets are sometimes written in different ways, for example 28 x 43 x 53. Eh? What this means is 28cm face width, 43cm across the face with the side gussets opened outwards (this is the width of the tube of plastic from which it's made; get it?) and finally the height. You may see it written as 28 x 15 x 53, which shows the gusset separately. Confused? Call us on 01903 202 333.
There is a trade convention of plus/minus 10% on size variation, so if size really matters, you should allow for this.
Mechanically finished paper
A paper that is sometimes simply called a 'mechanical' is paper such as newsprint made from low quality pulp, for example trees minus their leaves but including bark, and pulped mechanically (ah, yes, now we understand a bit). The paper will have lignin and other impurities remaining in it, which is why your newspaper turns yellow in the sun.
Micron
Metric measurement of thickness of polythene film or card. 1micron = 4 gauge. So 45 microns = 180 gauge. Interestingly (well, we think it is) polythene is specified in microns (thickness) but paper is usually specified in GSM, which is a unit of weight.
Millinery bags
Simple brown paper bags, and getting more popular again because they are so easily re-cycled or composted. Also called kraft bags, retail bags, counter bags or fruit bags, these are low-cost bags, usually without a gusset, made of unbleached brown kraft paper.
Negative
A total inversion of a positive image, in which light areas appear dark and vice versa. A negative colour image is also colour reversed, with red areas appearing in cyan, greens appearing magenta and blues appearing yellow. Film negatives usually also have much less contrast than the final images. (Thank you, Wikipedia, October 2010).
Offset litho
See Litho
Parchment paper
See greaseproof.
Patch handle
A plastic carrier bag with its handles formed from punched out apertures, with a transparent patch welded on the inside to reinforce the handle area.
PEFC
Programme for the Endorsement of Forest Certification. Claims to be the world's largest forest certification organisation. An international non-profit, non-governmental body dedicated to promoting sustainable forest management.
Percentage
The size of the dot, in tone or process print. The percentage refers to the amount of substrate that is inked in a given area. The bigger the percentage, the stronger that colour will apppear. By varying the percentage (dot size) and printing different colours in the same area, a photographic full colour image can be created. Dots usually print bigger than they appear on artwork. This is called "dot gain".
Pounds
American measurement of paper weight. See GSM.
PP
Polypropylene film. There are two types:
Cast, which is very clear, but tears easily in some directions; used for food packaging.
Blown, which may be less clear but is tear resistant in all directions.
Polypropylene ropes
Rope handles made of polypropylene. When woven, the effect is an attractively soft feel like cotton, and a glossy finish like silk.
Process print
The method of printing a full colour image such as a colour photo, using the 4 basic 'process' print colours- cyan, magenta, yellow and black. It's a very long-established colour printing method, still the basis of almost all colour half-tone printing, and still a miracle!
Proof
A document which shows the text, images, colours, colour split and positioning of the print elements before printing starts. APL Express will check your proof of your carrier bag, but its correctness remains the client's responsibility not that of APL. The client must carefully check it and approve it or specify any required corrections, as errors can and do occur, and the client will be responsible if the proof is passed without required corrections.
Register
In printing, the position of a colour, relative to where it should be, or relative to other colours.
Ribbed brown kraft
Brown kraft paper with shaded stripes to simulate a ribbed watermark, originally the marks left by the wire mesh on which the paper is formed.
Rope handles
There's a choice of materials for rope handles: cotton (matt finish), acrylic, (matt finish) or polypropylene (gloss finish), all usually braided in round section.
Rubber
A traditional name for flexographic printing blocks or stereos, because they were originally made from... natural rubber.
Scotchban
A manufacturer's brand of greaseproof paper.
SOS
Self opening satchel (not a lot of people know that) - the most popular style of machine made paper carrier bag.Twist carrier bags, like APL Express's but without the handle, used to be called SOS bags. The origin is that a satchel is a type of bag with a side gusset, like the old fashioned school satchels (now rather back in fashion). The reference to "self opening" may be down to the fact that they do open easily, possibly automatically on a production line, and they stay put ready for filling.
s/s
Same size, a term used to describe artwork or a proof, referring to its dimensions relative to the final size required. Never assume that artwork or a proof are s/s to the finished article.
Stack press
A simple multicolour flexographic press for printing work that does not require close colour registration.
Stereo
Traditional name for flexographic printing blocks.
Substrate
The material which is being printed, in other words what the bag is made of - cotton, jute, paper, plastic etc.
Sulphite paper bags
White paper bags that are ideal inexpensive counter bags for gift shops, sandwich shops, bakers, etc using large quantities. The paper is food-safe, and generally of 33 gsm. They are strung in 100’s for convenience and come in packs of 1,000 or 500.
Sulphite paper usually has a high recycled content together with mechanically pulped low grade wood chip, which may include bark and other impurities. Sulphite paper bags can be a little grey compared with kraft, although APL Express make every effort to source sulphite that is as white as possible. Like newsprint, sulphite can turn yellow in sunlight because of the remaining lignin content in the relatively unrefined paper. But sulphite paper bags are popular because they're very economical, they're food-safe, and they are 100% recyclable. AND - they can actually achieve high levels of recycling because it's so obvious to people that they can go into their paper bin for kerbside collections).
Tape handles
Kraft stock carrier bags offered by APL can have flat handles or twist handles, in both cases the handles are secured to the inside of the bag for neatness. Flat tape handles are made from (typically) five layers of folded paper, for strength. They are a cheaper alternative to twist handles. Each end of the handle is resin glued between two kraft paper reinforcing squares. The paper squares are then glued inside the bag. The result is neat, immensely strong, hidden, and stays upright. The handles and the bag are 100% biodegradable and recyclable.
Flat cotton tape is used, of course, for APL Express's cotton carrier bags.
Thin film
Used to describe HDPE bags of around 25 micron and less.
Turnover top (TOT)
Turnover top carrier bags have the top folded over inwards to provide a double thickness around the handle. In the case of a paper carrier, this will take a rope handle, or in the case of plastic bags, the top is turned over and welded into place before the handle aperture is punched out.
Twist handles
Kraft carrier bags offered by APL can have tape handles or twist handles, secured to the inside of the bag. Twist handles are made from two ribbons of paper: the first ribbon is twisted to make a core, and the second ribbon is twisted around the first. The result is a paper "rope" which has surprising, extraordinary strength. Each end is resin glued between two kraft paper rectangles. The rectangles are then glued inside the bag. It's neat, strong, hidden, stays put, and is entirely biodegradable or recyclable when the time comes.
Two up
A print term to describe printing two images along a cylinder, which produces twice as many images per rotation. 3 up. 4 up, etc.
Two round
To print two images around a cylinder.
UV ink
Ink that cures under ultra violet light, and is more rub-proof than water or solvent based inks.
Varigauge
A carrier bag where the polythene at the top of the bag is double the thickness of the bottom of the bag. The handles are punched through this strengthened area. As long as the punched-out centres are removed (Yes, APL's are) it's a very neat solution, and immensely strong... which is why we selected varigauge, such as this
for our website offer.
Vegetable parchment
See greaseproof.
Vest
A supermarket style of carrier bag, where the handle is continuous with the main body of the bag. The handle is cut out of a pre-folded and welded tube, effectively creating 8 thicknesses of material to carry the weight in a material which may be only 8 micron thick.
Visual
An idea, sketch or set of instructions to a printer. Not artwork.
Weight
The standard measure for the weight of polythene bags is based on 1,000 polythene bags in kilos: width x (height + half gusset if any) x thickness in microns, all divided by 5,435 (LDPE) or 5,263 (HDPE).
Woodfree
A type of paper. Confusingly, it does not mean paper made from a wood-free pulp. It is chemically rather than mechanically pulped paper. Very white compared with kraft, and it retains its whiteness, but its shorter fibres give less mechanical strength compared with kraft or art. It can be clay coated.
If you've read to the end of this Glossary, thank you, you deserve a medal, and if you're such a glutton for punishment you may also enjoy our easy-to-read Buyer's Guide. Enjoy!
© Copyright 2010 APL Express Ltd. You must if you want to reproduce this APL Express Glossary in whole or in part.
