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Q&As since 1989


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ANODISED LITHO GRADE OFFSET PRINTING ALUMINIUM PLATES

2000

Respected Sir,

CAN YOU HELP FOR THE FOLLOWING.?

1 WE are in the SHEET FED & WEB OFFSET PRINTING business.

2 We are using Lithograde Aluminium Offset plates for Sheetfed & Web printing.( Heidelberg Harris M/c.)

3 We are not getting desired Print run length even after right baking the plates before mounting on m/c. ( We are not getting even min. 200,000.print impressions)

4 The plates get Weak or Plate Crack before 200,000.impressions.om Highspeed Heidelberg Harris Web Printing M/C.

4 Please tell us 1 Right Aluminium Alloy 2 Right Temper H14, H16, H18 or if any? 3 Ideal Tensile Strength values.

B) Standard testing procedures. 1 Determination of photosensitive layer thickness of anodised ( presensitised) lithograde aluminium plates. 2 Determination of Break Down Voltage Tests. 3 Determination of Aluminium Surface Roughness. Please let us know standard testing procedures & International Specifications.

PRAKASH AJAREKAR
- NEW MUMBAI, MAHRASHTRA India.

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Please let us know whether you process coil or sheet.

3103 or 3003 alloys are best for cracking, but beware of electrograining problems.

Production conditions to get optimum results depend on the chemistry you use - whose light sensitive material are you using etc.

Richard Hutchinson
- Selby, England
2000

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THIS RESPONSE TO THE ANSWER OF RICHARD HUTCHINSON - THANK YOU VERY MUCH.

1 Anodising ( presensitised Al.) is in coil form.

2 We use chemistry of Technova ( Du point)

THANKS & REGARDS.

PRAKASH AJAREKAR
- NEW MUMBAI, MAHARASHTRA - India
2000

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2002

1.First you must be satisfied that the film has sufficient density to hold back the light form the wanted image area.

Check with a stepwedge that you are giving the correct exposure (Clear 3 on positive plates) (Solid 4 on Negative plates).

Be sure that the Printer is not using a chemical that can attack the image. Using an unexposed plate pour a small quantity of each chemical onto the plate, in particular the blanket wash, plate cleaner, and most of all any blanket rejuvenator that he is using. If any of these chemicals attack the coating within 3/4 minutes then this could be the problem.

I recently had a problem with pre mature image loss visible over the whole area of the plate. The offending chemical was the blanket rejuvenator this was like deletion fluid when it hit the plate. He now takes great care and thoroughly cleans the blanket with blanket wash after treating with Rejuvenator.

Another possibility is the printing down frame if it does not use light units but rather the old method of leaving the light source on for a set amount of time i.e. minutes. In this case plates made late in the evening may suffer a power surge because other companies may have closed for the evening giving extra electric power to the area. If your printing down frame has a light integrator then using units of power will solve that problem.

Regards, Terry Cummins

Glad to offer advice particularly on CTP which nearly broke my heart last year.

Terry Cummins
graphic supplies - Ireland

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1.Which instrument is used for checking grains on offset plate?
2.PRINT Analyser instrument can be used for checking grains?
3.composition of offset plate developer?

ALAPINI KASTURE
- Vapi, Gujarat, India
2005

What are the advantages financially & time wise of using baked thermal plates apposed to violet plates?

DIANE LAW
- SOUTH YORKSHIRE, ENGLAND, UK
2006

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Q. Am doing printing business. Asking whether the printed plates can be grained; if so, how it will have a long run? And also I need information about ps [Ed. note: photosensitive?] coating.

Aravinth Raj
- Tamil Nadu, India
June 12, 2013