glossary 

We have put these explanations together to introduce you to some terms in ours and other companies' websites and documents. We do not represent them as being complete, (they are not) definitive, or 100% accurate. Please email us comments, corrections, and omissions, as we are keen to progress and refine these pages for everyone's benefit. We would also welcome links to and from more authoritative sites.

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Artwork

The image which the client wants produced and has been approved as a proof by the client. Anything less than this is not Arwork, it is a visual.

Artpaper

This paper is less dense than Kraft paper, and is therefore usually supplied in a heavier grammage which gives the carrierbag a bulkier feel for similar cost.

Blend

Often refers to a mixture of HDPE and LDPE, mixed at the time the film is made. The result blends the characteristics of each type

Bleached white Kraft

Common paper bag or counterbag material.

Blocks

Used for flexographic printing. One block is required per colour each side of the bag being printed. Blocks cost according to 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 and placing it on the bag front and back.

Brown Kraft

Unbleached Kraft. Can be plain or have a manipulated ribbed effect.

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. Therefore usually laminated to protect the ink from cracking

Co-extrusion

The process of making a film which is say, HDPE on one side, and LDPE on the other. eg a rope handled carrierbag 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 job, or the process of scanning a multicolour image such as a transparency to isolate the 4 process colours of Cyan, Magenta, Yellow, & Black.

Cylinder

Printing blocks are placed on a cylinder and each turn of the cylinder will print one image. The circumference of the cylinder will therefore dictate the bag width or height.

Duffle

A style of carrierbag. A rope attached to base for carrying also closes top by pulling.

Embossing

Creating a raised area, eg over text to enhance it. Embossing does not have to follow a print area: blind embossing. Debossing is to produce a depressed area to similar effect.

Extruder

A machine which produces Polyethylene film. Granules are melted and drawn out in a tube bubble to cool. The quicker 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.

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 volume paper carrierbags and flexible packaging.

Gauge

One thousand of an inch. A British Imperial Unit of measurement to measure the thickness of polythene film. Giving way to metric. Conversion is easy: 4 gauge = 1 Micron. eg a popular carrierbag gauge of 200 is 50 Micron.

Greaseproof

A grease & fat resistant paper. Also Glassine (Least resistant), Vegetable Parchment (more resistant than Glassine, whiter than Greaseproof) Greaseproof (most resistant)

GSM

A measurement of paper. Literally, Grammes per square meter. ie if a square meter of paper were weighed, how many grammes would show on the scales. It is worth remembering, if you buy a lot paper, that it is a measurement of weight, not thickness or strength. A Kraft, which is relatively dense and with long strong fibres, will be thinner than a bulkier, less dense Art 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 site fold or bottom fold which adds capacity to a carrierbag. In Aperture Handle carrierbags the gusset is the final dimension 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, and can be supplied as thin film, eg 8-18 Micron economical counterbag or carrierbag, or as "thick film" 30-120 Micron carrierbag.

Kraft

A high quality construction paper which can be additionally clay coated one or both sides.

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. Can be mixed with HDPE to make a blend.

Litho

Short for Offset Lithography. A printing method used for printing paper. A non relief process based on the principle of oil repelling water on re-usable flexible metal plates. Produces a higher quality image than Flexographic on paper and is used for top of the market handmade carrierbags.

LPI

Please see DPI

Laminate

A very thin plastic film which can be "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. Laminates can be overprinted with Hot Foil and Gloss or Matt UV varnishes. Generally 12 Micron thick (gloss) or 15 Micron thick, (matt) and adds about 30 GSM. weight to the finished product.

Micron

Metric measurement of thickness of Polythene film or Card. 1 Micron = 4 gauge. eg 45 Micron = 180 gauge. See gauge. Interestingly, (well, we think interesting) Polythene is specified in Micron, (Thickness) but Paper is usually specified in GSM, which is a unit of weight.

Machine Finished

(MF) a process of mechanically polishing paper between cylinders

Machine Finished

(MF) a process of mechanically polishing paper between cylinders

Machine Glazed

(MG). Usually on Kraft of 60 GSM up. Rougher than MF

Mechanically Furnished Paper

Paper eg newsprint paper, made from low quality pulp, eg trees minus their leaves but including bark and pulped mechanically. The paper will have remaining lignin and other "impurities" which is why your newspaper turns yellow in the sun, and who knows, may grow back into a tree when planted.

Measurement

In Bagspeak, the opening measurement is always first, so this will usually be the width. So a poly carrierbag, the sort with an aperture handle and a "gusset" or pleat in the base will look like this: 38x46+10, which means 38cm wide, 46 cm high, plus a 10 cm gusset, ie 5cm in and 5 cm back out again. Bags with side gussets are sometimes written different ways:- eg 28x43x53. eh? What this means is 28cm face width, 43cm across the face with the side gussets opened outwards (ie the tube width) and finally the height. You may see it written as 28x15x53, which shows the gusset separately. Confused? Give us a call! There is a trade convention of plus/minus 10% on size variation, so if size is critical you should allow for this.

Negative

Aceteate film where the image is reversed around, ie the colour to print appears clearer than the surrouning area.

Patch

A transparent patch glued on the inside of an aperture handle carrierbag to reinforce the handle area.

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: Two types: Cast: Very clear, but tears easily in some directions. Used for food packaging. Blown: May be less clear but tear resistant in all directions. Polypropylene Ropes: When woven, produces a gloss finish compared with cotton or Acrylic.

Process Print

A common and ingenious method of printing a full colour image such as a colour photo, out of 4 basic colours- cyan, magenta, yellow and black- which, when combined in varying amounts according to a dot size, will produce any colour.

Proof

A document which shows the text, colours, colour split and positioning of a print order. It is the client's responsibility to carefully check a proof, as errors can and do occur, and the client will be responsible if errors are passed without correction.

Quantity

An initially strange convention in packaging allows manufactures to deliver up to plus/minus 10% on the contract quantity and invoice for the actual amount delivered. Whilst superficially this is a shoddy practice, there are good reasons: it avoids waste. Carrierbags are printed from a reel of paper or poly, initially by weight. After they are printed they are "converted" into carrierbags, at which time they are machine counted and placed by machine into swatches of 50, 100 etc. At the initial weighing stage, the amount of reel used in setting up to good print is an unknown. If the set up to good print is rapid, it would be extremely wasteful to scrap good print. Likewise, it would be uneconomical to set up the press again for a small underun. Most carrierbags are used by retailers who are using carrierbags all the time, so up to +/-10% is not an issue, and they gain from waste saving and efficiency which is ultimately passed on in a free market, and an extremely price conscious industry. Obviously this does

Register

The position of a colour, relative to where it should be, or relative to other colours.

Ribbed Brown Kraft

Brown Kraft with a shaded stripes to simulate a Ribbed watermark, originally the mark left by the wire mesh on extraction from the paper pulp.

Rope

Can be cotton (matt finish), Acrylic, (matt finish) or Polypropylene (gloss finish) Is usually round section braided, the diameter as agreed.

Rubber

A traditional name for Flexographic printing blocks or stereos, because they were originally made from... natural rubber.

Scotchban

Imitation Greaseproof paper.

SOS

Self Opening Satchel. (not a lot of people know that) The most popular style of machine made paper carrierbag.

SS

Same Size. A term used to describe Artwork or a proof, referring to its dimensions relative to the final size required. Never assume Artwork or a proof is SS.

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 bag Material. LDPE, HDPE, blend, Paper, Fabric, etc.

Sulphite

A low grade inexpensive paper bag substrate, can be rather grey compared with bleached white Kraft, and yellows quickly.

Tape

Cotton or other material woven Flat Tape can make good alternative to rope.

Thin Film

Used to describe HDPE bags of around 25 Micron and less.

Thin Film

Used to describe HDPE bags of around 25 Micron and less.

TOT

Turnover top. A Carrierbag that has the top folded over and welded in place to provide a double thickness around the handle or to take the rope for a duffle carrier.

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

Cures under ultra violet light. More rub-proof than water or solvent based inks.

Varigauge

Thicker gauge polythene across the top of a carrierbag to strengthen around the handle.

Vegetable Parchment

See Greaseproof.

Vest Style

A supermarket style of carrierbag, originally patented, where the handle is cut out of a pre-folded and welded tube, effectively creating 8 thicknesses of material to carry the weight of a weekly shop in a material which may be only 15 Micron thick.

Visual

An idea, sketch or set of instructions to a printer. Not Artwork.

Weight

1,000 Polythene Bags weigh in Kilos: Width x (Height + half gusset if any) x Micron, all divided by 5435 (LDPE) or 5263 (HDPE)

Woodfree

A type of paper. Confusingly, does not mean made from a wood free pulp. It is chemically rather than mechanically pulped paper. Very white compared with Kraft and retains its whiteness, but shorter fibres give less mechanical strength compared with Kraft or Art. Can be clay coated.