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Offset Plates

Written by  Arcotrade Ltd.
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ARCOTRADE LTD Presents OFFSET PLATES made by  Untitled-2, Slovenia

KEMOLIT® offset plates

KEMOLIT® РСР offset printing plates, a production of the Slovenian factory Cinkarna, are suitable not only for a conventional printing, but also as a СТР plate. The conventional plate becomes СТР plate when exposed to UV laser system, which is first developed by Lȕscher with platesetter Xpose, designed for UV-sensitive conventional plates, and also it can be used in Basys print systems with UV laser systems.

 

Lithographic aluminium alloy, from which the plate is made, has properties that made plate suitable for the production and printing technology demands.  Grain size, hydrophilic properties of the anodic oxide layer and proper composition of the light sensitive coating, provide the user with numerous benefits within plate room and pressroom areas:

-          higher sensitivity cuts the time of exposure,

-          micro-grained surface of the plate improves the contact between film and plate and image without errors,

-          colour of the plate provides excellent final image contrast,

-          sensitive coating provides also faster development (hand or machine). The proper regeneration of developers enables their biggest capacity and removes the sediment,

-          tough, durable anodized surface provides good resistance on scratches and oxidation,

-          fine electrochemically grained surface gives excellent ink-water balance and high quality reproduction,

-          above mentioned characteristics made the plate suitable for medium to long run lengths. For hard conditions during printing or for printing with UV inks, the plate can be baked.

KEMOLIT® РСР is a sophisticated plate with a special surface coating which provides better adhesion between film and the plate in the vacuum copying frame. Since the effect of under-copying is reduced to the minimum, the plate can also be used in printing large raster areas.


Way of ordering

KEMOLIT® plates are made in different alloy thickness: 0,15 mm, 0,30 mm, 0,40 mm.

KEMOLIT® plates come in different sizes up to a maximum width of 1500 mm. They can be used in printing presses of various producers. With “ROT” designation we guarantee accurate cutting as far as the rolling direction of the lithographic aluminium strip is concerned. This is particularly important in high-speed printing presses. Plates labeled “ROT” are used in roto offset printing. With „REP” label we guarantee for high control of flat parallel alignment of the offset plates, which is extremely important in repetitive copying machines. Plates labeled “CPC” are used in computer –aided ink setting printing systems. 0,15 mm thick plates used for printing in smaller printing presses, can be punched upon a request, with the following standard perforations:

Punch holes are marked „р1”, „р1Р”, „р2”, „р4” and „р6”. Other perforations are available upon a special request.


Untitled-3

 

Upon your order, please quote:

-          plate type

-          plate thickness, width and length

-          type: “ROT”, “REP” or „СРС”

-          for web printing and CPC systems also quote the side of mounting the plate to the cylinder

-          type of punching and number of holes

 

Packaging:

thickness 0,15 mm: 100 pieces per cardboard packet

thickness 0,30 mm up to format В0: 50 pieces per cardboard packet

thickness 0,30 mm over format В0: 40 pieces per cardboard packet

thickness 0,40 mm up to format В0: 40 pieces per cardboard packet

thickness 0,30 mm over format В0: 30 pieces per cardboard packet


Processing chemicals – Preparation of the printing plate

Code

Description

Average consumption ml/m2

Р-76

Developer - R

800

Р-76С

Developer –RC- concentrate

80

Р-75

Developer - РСР

240

Р-75С

Developer concentrate

35

Р-47

Universal gumming soltion

50

Р-211

Activator (plate cleaner)

As required

Р-73

Corrector

1



Exposure

As conventional plate

Exposure time depends on the type and strength of light source and its distance from the plate. The most suitable is a metal halogen bulb and a vacuum copying frame. The frame must provide good contact between the film and the plate.

The Plate Control Wedge copied along with the film helps to determine the exposure time.

The optimum exposure is achieved when after developing the first printing step in the continuous-tone wedge is four or five. Or 15-micron circle became visible. This value corresponds to the density D=0,60 or D=0,75.

It is recommended using diffusion foil to prevent film edge marks and adhesive tape shadows.

This foil does not have influence on halftone dots.

After the exposure and developing, the image on the plate is still light sensitive, therefore the room should be illuminated with yellow safety light or subdued daylight.

As CTP plate

When the plate is used as СТР plate – for exposure are needed UV laser diodes which give energy in suitable wave – length (405 nm). These diodes are assembled in XPose Luscher UV plate setter unit and Basys Print UV plate setter unit. It is recommended that power of diodes should be between 60 – 70 mJ/m2 Exposure time is changing together with power of diodes and it depends on number of diodes assembled in plate setter (low number of diodes – longer exposure time, higher number of diodes – shorter exposure time).

Manual developing

KEMOLIT® РСР plate is developed with the P-76 Developer-R or P-75 Developer – PCP. The developer can also be prepared by diluting one part of P-76C Developer – RC Concentrate with nine parts of water. The developer temperature should be between 20 and 250.

First the developer has to be smeared over the entire plate surface with a soaked pad to ensure proper and even developing. The developing is then poured over the plate and spread with the pad by using even strokes, starting from the edges and working in towards the centre. This has to be done twice, each time taking half a minute. The remaining developer has to be removed with a rubber wiper. Finally, both sides of the plate are washed under running water and dried with the wiper.

 

Automatic Developing

KEMOLIT® РСР plates can be used for developing in automatic processors for positive working pre-sensitized plates. The developer temperature must be between 23 and 250C. Automatic developing is done by applying Р-75 Developer-PСР. The developer can be improved by adding P-75 Developer-PCP or P-75C Developer-PCP (concentrate) mixed with water in the ratio 1:3.

Automatic processor developer may be prepared by diluting P-75C Developer-PCP (concentrate) with four parts of water.

Due to the diluted light-sensitive layer the developer tends to foam. This can be prevented by adding small quantities of P-77/1 Antifoaming Agent, which depends on developer’s quantity and how fast it is exhausted, altogether approx. 0,1%.

Image corrections

Unwanted printing elements are removed by applying of Р-73 Corrector-Gel with a pencil brush or Р-73/1 Corrector-Pencil. After approximately 1 minute the plate should be washed under running water with a sponge. Once the corrections have been made the plate is gummed again.

Caution! Keep the bottle or pencil with P-73 Corrector Gel closed!

Gumming up

Р-47 Offsetgum-UNI is poured over the plate and spread as evenly as possible over the whole plate surface with a sponge to form a thin film.

Gumming can also be done in the automatic processors as the last step before drying.

Normally, plates that need corrections are not gummed, but if they are, the gumming layer must be wiped off with a sponge soaked in water before the corrections are made.

 

Conservation

Printing ink from the wet plate must be removed with Р-211 Activator. The plate is then rinsed with water and gummed up with Р-47. After the treatment it is wrapped in paper and the plate can be stored for over one year.


Last modified on Saturday, 12 March 2011 18:31
Arcotrade Ltd.

Arcotrade Ltd.

ARCOTRADE Ltd was created in 2006 to present the bulgarian, romanian and moldovian markets with another alternative of the self adhesive paper and cardboards as representative of Arconvert SPA, Italy. 

The good relationships with our clients and our striving for flexible solutions for the different print demands we meet made us a reliable partner for the printing industry. We offer high quality of the products and the services we present at reasonable prices.

The feedback that we recieved from the market and the constant strive for satissfying our clients demands made us to develop the assortiment of products that we offer. Along with the Self-Adhesive paper, we offer to the market different solutions for printing and advertisment like Art Cardboards Fabriano, special materials for digital printing, offset plates and others.

Website: www.arcotrade.bg