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Jun 1, 2002 12:00 AM
To paraphrase a popular tire manufacturer's slogan, so much is riding on your offset printing blanket. With today's tiny margins, the pressure is on to provide optimum print quality while avoiding blanket smashes and other productivity killers.
Fortunately, sheetfed- and web-press blanket options abound. Although some blankets are specifically designed for certain applications, such as coating or UV printing, most are either conventional or compressible. A conventional blanket consists of a rubber compound applied to a fabric backing — up to four plies of fabric are cemented together, creating a “carcass.” Compressible blankets are similar, but their backings also include one layer of resilient material. A compressible blanket permits increased packing height without generating a corresponding increase in printing pressure.
Blankets are manufactured in three surfaces: cast, a surface finish produced by curing paper and talc; ground (or buffed), a mechanical surface-finishing process; and texturized, a chemically produced finish.
Typical life expectancy for offset blankets is anywhere between five million and 30 million impressions, depending on the substrate, printing process and inks used while the blanket is on press. As one vendor quips, blankets never die of natural causes — they are always murdered.
Of course, a blanket is only as good as the person installing and maintaining it. Here are some blanket highlights from leading suppliers.
Day International's (Dayton, OH) SteelBack is currently the industry's only blanket with stainless-steel backing. Designed for heatset web presses (it is currently available only for the Heidelberg M-1000 press), the steel carries the tension load and allows the blanket to print all the way to the gap. No packing is required, and there is no gauge loss at the gap, so users can print full bleeds. With just one tensioning step, it is easier to install and is said to last longer than traditional fabric-backed blankets. The steel layer also eliminates moisture wicking from the backside and eliminates registration problems. The SteelBack features a ground surface.
The dayGraphica 3000 is Day's most popular sheetfed blanket. Its
dark-blue surface is highly ground and buffed, which is said to
enable uniform gauge and consistency. It is compatible with
waterless systems, faster presses, alcohol replacements, new
solvents and fountain solutions, vegetable-oil-based inks and
recycled/alkaline-based paper. Its closed-cell, compressible layer
reportedly enables fast rebounding and enhanced durability. It is
available in three-ply (0.067-inch) or four-ply (0.077-inch)
thicknesses; its face compound is composed of a solvent-resistant
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DUCO International's (Slough, England) Superstrip 4 is a stripping blanket for online stencil coating in sheetfed and packaging applications. It is suitable for inline varnishing units of multicolor presses using either aqueous or UV coating. It features a polyester support layer that reportedly provides dimensional stability in all directions, ensuring that stencil size remains correct even when the blanket is removed from the press and stored for subsequent re-use. The Superstrip 4 has an easy-to-peel stripping layer that allows quick, trouble-free stencil preparation. Its smooth surface enables optimum varnish gloss, and due to its deep stencil profile, frequent washups aren't necessary.
At Ipex, DUCO introduced the DUCOsmart System, a
blanket-positioning device that enables gapless running on existing
presses. The system consists of an applicator, a roll-around table
and a mounting jig that aligns the applicator with the blanket
cylinder. It positions adhesive-backed blankets on press cylinders,
working in conjunction with a patented fillet system that fills the
gap on the blanket cylinder. The uninterrupted surface reportedly
reduces cylinder bounce at high press speeds, prevents lateral
blanket movement, stops solvent ingress, reduces gauge loss and
offers better smash resistance. It is distributed in the U.S. by
NDI (Rockland, MA).
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The SX-10 from DYC Supply Co. (Teaneck, NJ) is an offset
compressible blanket suitable for high-speed commercial printing
and newspaper web printing, on both coated and uncoated papers. The
blanket features a high-tensile backing that prevents stretching, a
ply layout that minimizes gauge loss, a high-yield compressible
layer that absorbs pounding at high speeds and a rubber surface
that is resistant to low-energy inks and solvents. It also includes
a finished ground surface for better release properties and a
cerise color that reportedly allows users to see definite images on
the blanket. A water-resistant backing minimizes wicking and
delamination. The thickness is guaranteed to be within 0.0008 inch
from roll to roll.
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The SectorCoat DG blanket is manufactured for Gerber Innovations (Manchester, CT) by Day International specifically for the Gerber Sector blanket-production system, which automatically processes blankets for spot-, knockout- and flood-coating applications. (See “Eliminating hand-cut coating blankets,” May 2002, p. 49.) The SectorCoat DG can be used in aqueous and UV operations; it is optimized for spot-coating applications. Its polyester backing reportedly prevents image distortion and maintains blanket integrity for reprinting. Its pre-punched sprocket pattern ensures smooth movement and accurate cutting. It features a light-blue color, a ground and buffed surface finish and a total thickness of 0.062 inch.
Gerber's SectorCoat Poly is a premium strippable coating blanket
for aqueous operations. Its polymer surface compound is said to
enable excellent coating transfer and precise spot coating. Its
double-polyester base ensures fast, easy pressroom cutting and
stripping, and on-press endurance. It includes polyester backing
and the pre-punched sprocket pattern for accurate cutting. The
SectorCoat Poly is black in color; it features a cast surface
finish, a urethane polymer face compound and a total thickness of
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Heidelberg USA's (Kennesaw, GA) Perfect Dot blanket is supplied
as standard equipment with all Heidelberg sheetfed presses —
it can also be purchased separately. It is said to offer optimal
ink transfer, excellent dot reproduction and stable quality on both
screens and solids. It also has a guaranteed gauge consistency, a
fine-grind surface face and an additional fabric layer for
increased durability. It is also said to be highly resistant to
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The Polyfibron XT555 from MacDermid Printing Solutions (Atlanta) is built on a carcass of compressible fabric over foam topped with a buffed rubber surface. It reportedly provides high-definition screen values over a wide variety of paper weights and stocks, on sheetfed and web presses. It is compatible with UV and conventional inks and features a dark-green color. The blanket can handle stochastic and waterless printing and is also said to function well in alcohol-free pressrooms.
MacDermid's Graffity blanket for web presses is constructed to
avoid trapping air bubbles between fabrics. As a result, gauge loss
is suppressed. Unlike most 0.077-inch blankets, Graffity has three,
rather than four, fabric plies: The extra space allows increased
thickness in the compressible layer to decrease smashing, piling
and linting. Its surface is micro-ground and polished for excellent
dot shape, reduced dot gain and high print densities.
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The Sapphire blanket from Phoenix North America, Inc. (Fords, NJ) is characterized by a highly elastic compressible layer that is said to extend its longevity and improve print quality. Its blue, superfine-ground surface reportedly yields excellent print results in screen as well as in solid print. It is said to be highly resistant to smashes and chemicals, and can easily handle format changes. Ink and paper-dust buildup is minimized, reducing washup frequency. It is available in three- and four-ply thicknesses.
Phoenix's red Ruby blanket, designed for UV applications, has a
surface attuned to UV inks and washing solutions. It features high
resistance to heat and chemicals, which enhances its durability. It
has an extremely fine surface structure that ensures a uniform
solid print and a sharp dot. Special compound additives,
incorporated in the surface, reportedly enable good paper
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Prisco (Newark, NJ) just introduced the Priscolith Conti Air Zenith blanket for high-speed web offset. It has a sealed-air compressible layer said to prevent sinking and ultimately enables the blanket to last longer. It features a precision-ground surface that provides good ink transfer and uniform printing of solid areas. The face compound and carcass construction contribute to sharp dot rendition and register control, as well as easy washups and longer wash intervals. The fabric-backed Zenith can reportedly be used on all press units, regardless of paper-feed characteristics. Its low-stretch carcass provides stability at the gap. It is available in 0.067- and 0.077-inch thicknesses.
The Priscolith Conti Air Crystal is a compressible, strippable
blanket with a precision-ground blue surface suitable for high-end
sheetfed printing — it can produce very sharp dots and vivid
solids. The surface also reportedly enables quick release, good
ink-transfer properties and reduced ink piling. Its compressible
layer is composed of pockets of encapsulated air under positive
pressure, which reportedly ensures uniform printing pressure across
the entire surface of the blanket. Its compressibility and soft
dampening face are said to provide high resilience and durability.
It is available in 0.067- and 0.077-inch thicknesses; its backing
is composed of fabric.
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The Vulcan Reflection & SRF blanket from Reeves Brothers, Inc. (Spartanburg, SC) is the company's top-of-the-line sheetfed and web offering. It features a closed-cell compressible subface layer that fights smashes, resists gauge loss and limits edge cutting when changing widths. The layer is also said to reduce doubling and slurring. The face of the blanket is composed of a solvent-resistant rubber blend in a dark-blue shade. The subface layer provides extra mechanical strength. Its fabric backing is water- and solvent-proof. The Reflection & SRF blanket is available in three- or four-ply versions, with a fine buffed (SRF) or cast finish.
The Vulcan Alto is a compressible blanket suitable for
high-volume publications and commercial printers; it is
specifically designed for high-speed heatset web presses. Its
low-stretch carcass is said to maximize on-press stability. It
features a three-layer surface that is said to provide greater
resistance to cuts, abrasions and smashes. The Alto also contains a
closed-cell compressible layer, ensuring instant rebound and
excellent performance. The face is composed of a solvent-resistant
rubber blend and is green in color; the surface is buffed, enabling
the production of full solids, sharply formed dots and rich
contrasts. The fabric backing is reportedly water- and
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