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 transfer the image to the substrate.
Artwork.
The
image, which the client wants produced and has previously been
approved as a proof by the client. Anything less than this is not
artwork, it is a visual. Back to top
Blend.
Often
refers to a mixture of HDPE and LDPE, mixed at the time the film is extruded. The result blends the characteristics of each type of material.
Back to top
Blocks.
Used for in flexographic printing. Also called
stereos or cyrels, one block is required per colour on each side of
the bag being printed. Broadly, 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 from the
anilox, and placing it on the substrate. Back to top
Bromide. Photographic paper, with an image on
it, for placing under a camera. Back to top
CI Press.
Common Impression Press. A
flexographic press used for printing to very close registration and
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. Back to top
Co-extrusion. The process of making a film which is
for example, HDPE on one side, and LDPE on the other. E.g. a rope
handled carrier bag can be HDPE (naturally matt and tactile) on the
outside, with the puncture resistance and elasticity of LDPE on the
inside. Back to top
Colour Separation. The instructions for a multicolour job,
or the process of scanning a multicolour image such as a
transparency to isolate the four process colours of cyan, magenta,
yellow, & black. Back to top
Corona Treatment. The process of treating polyethylene
film to give it a key to retain flexographic
ink Back to top
Cylinder.
Printing blocks are placed on a cylinder,
such that each turn of the cylinder will print one image. The
circumference of the cylinder will therefore dictate the bag width
or height. Back to top
Cyrel.
Dupont's
name for its material from which printing blocks are
made. Back to top
Designers. Those
who create designs. The world would be poorer without designers. As
printers we know that we have to proof a design to the client to
ensure that the artwork supplied will produce the result the client
is expecting. Back to top
Dispro. The process of compensating for the
stretch of a block when placed around a
cylinder Back to top
DPI. Dots Per
Inch. Printing millions of tiny dots of each selected colour
produces tones and process print. 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, to 100-130dpi for a
Flexo CI Press. Please note the metric equivalent is dots per
centimetre, beware that inch or centimetre is often unspecified.
LPI. Lines per inch is the same as DPI, but don't confuse DPI with
percentage which is the size of the dot. Note: - Please contact our
artwork department for advice on what we can achieve on our
machinery. Back to top
Duffle. A style of carrier bag. A rope attached
to base for carrying also closes the top. Back to top
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, the bigger the bubble, the wider the
film. The tube is often then slit and wound ready for
printing. Back to top
Film Positive. Transparent film acetate
with an image in black, one supplied for each colour. This is used
to make a negative prior to block making. The majority of artwork is
now supplied digitally. Back to top
Flexographic. A
printing method used for printing polythene, 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 bags and flexible
packaging is printed this way. Back to top
Gauge.
1/1000 of an inch. A British imperial unit of measurement to measure the thickness of polythene film. It is now giving way to metric, but conversion is easy: 4 gauge = 1 micron. E.g. a popular carrier bag gauge of 200 is 50 micron.
Gusset. A side
fold, or bottom fold which will add capacity to a carrier bag. In
aperture handle carrier bags the gusset is the final dimension e.g.
38cm wide x 46cm high + 10cm gusset i.e. 5cm in and 5cm
out. Back to top
HDPE. High Density Polyethylene. The high
density refers to the density of molecule chain in the polyethylene.
It is more crinkly and crackly than LDPE, and can be supplied as
thin film, 8-18 micron economical counter bag or carrier bag, or as
a thick film 30-120 micron carrier bag. Back to top
LDPE. Low Density Polyethylene. The low
density refers to the density of molecule chain in the polyethylene.
It is more elastic and stretchy and tears less easily than HDPE. It
has a softer feel and is glossier than HDPE. It can be mixed with
HDPE to make a blend. Back to top
Measurement. In
bagspeak, the opening measurement is always 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: 38x46+10, which means 38cm wide, 46 cm high, plus a 10 cm
gusset, i.e. 5cm in and 5 cm back out again. There is a trade
convention of plus/minus 10% on size variation, so if size is
critical you should allow for this. Back to top
Micron. Metric measurement of thickness of
polythene film. 1 micron = 4 gauge. E.g. 45 micron = 180
gauge. Back to top
Negative. Acetate film where the image is
reversed around, i.e. the colour to print appears clearer than the
surrounding area. Back to top
Patch. A
transparent patch glued or welded on the inside of an aperture
handle carrier bag to reinforce the handle
area. Back to top
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 appear. By varying the
percentage 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. Back to top
PP.
Polypropylene film. Available in two types,
cast, which is very clear, but tears easily in some directions, used
for food packaging and blown, which may be less clear but tear
resistant in all directions. Polypropylene ropes are also available
and produces a gloss finish compared with cotton or
Acrylic. Back to top
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. Back to top
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. The client will be
responsible if errors are passed without
correction. Back to top
Quantity An
initially strange convention in packaging allows manufactures to
deliver up to +/-10% on the contract quantity and invoice for the
actual amount delivered. Whilst superficially this may appear an
unusual practice, there are good reasons. It avoids waste. Carrier
bags are printed from a reel of polythene, initially by weight.
After they are printed they are converted into carrier bags, at
which time they are machine counted and placed into swatches of 50
or 100. 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
were rapid, it would be extremely wasteful to scrap good print.
Likewise, it would be uneconomical to set up the press again for a
small under run. Most carrier bags are used by retailers, so +/-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 not apply to unbranded
carrier bags which we stock and pick to your
order. Back to top
Register. The
position of a colour, relative to where it should be, or relative to
other colours. Back to top
Rope
.
Can be cotton (matt finish), Acrylic, (matt
finish) or Polypropylene (gloss finish). It is usually round section
braided, the diameter will be agreed with the
customer. Back to top
Rubber. A
traditional name for flexographic printing blocks or stereos,
because they were originally made from natural
rubber. Back to top
Stack Press. A simple, multicolour
flexographic press, for printing work, which does not require close
colour registration. Back to top
Stereo. Traditional name for flexographic
printing blocks. Back to top
Substrate. The
bag material LDPE, HDPE, blend, etc. Back to top
TOT.
Turnover top. A Carrier bag 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 bag carrier.
Two Up. A print
term to describe printing two images along a cylinder, which
produces twice as many, images per
rotation. Back to top
Two Round. To print two images around a
cylinder. Back to top
Varigauge. Thicker gauge polythene across the top
of a carrier bag to strengthen around the
handle. Back to top
Visual. An idea, sketch or set of instructions
to a printer. Not artwork. Back to top
Weight. 1,000
Polythene Bags weigh in kilograms: Width x (Height + half gusset if
any) x Micron, all divided by 5435 (LDPE) or 5263
(HDPE) Back to top