Plates Peeling off and Not Picking Ink

[ighodaro]

Our office runs a CTP service, where independent printers come to colour separate their jobs. Recently there have been series of report peeling-off of the imaged work on the plates when used for impression. Also they complain it is difficult for the plates to 'pick' inks and impress on the papers. Please what can I do to remedy this. Thank You

 

[ChrisZ]

What kind of plates?

 

[ighodaro]

HSV Photopolymer plate. AGFA Chemistry

 

[ChrisZ]

Issue can be:
1. Wrong focus.
2. Not enough exposure power.
3. Wrong pre-heat temperature.

Chris

 

[maxon]

Issue can be:
1. Wrong focus.
2. Not enough exposure power.
3. Wrong pre-heat temperature.

Chris

Poor focus, insufficient laser intensity or low preheat have to do with excessive image wear during the run. Emulsion coming off the substrate I believe points to a bad batch of plates.
When you say it peels off how does the plate look exactly, is it in large random areas ? Just short streaks here and there may indicate high pressure on prewash brush spraybar, spraying cold water onto plate coming out the preheat box - this is known to create weak spots and image holes/dropouts (this in case you have prewash stage in your plate processor).
Take a new plate out of the box, fog it in daylight, process as usually and hang it into a press colour unit run some 200 sheets see what happens.

 

[Alois Senefelder]

Hello ighodaro,


Question: 1) Do you "Image " the plates for your customers ? 2) Do the customer "Image" the Plates ?

Are they - Chinese Violet Photopolymer Plates ?

Regards, Alois

 

[ighodaro]

Poor focus, insufficient laser intensity or low preheat have to do with excessive image wear during the run. Emulsion coming off the substrate I believe points to a bad batch of plates.
When you say it peels off how does the plate look exactly, is it in large random areas ? Just short streaks here and there may indicate high pressure on prewash brush spraybar, spraying cold water onto plate coming out the preheat box - this is known to create weak spots and image holes/dropouts (this in case you have prewash stage in your plate processor).
Take a new plate out of the box, fog it in daylight, process as usually and hang it into a press colour unit run some 200 sheets see what happens.

Thank you very much for your response.

Peeling off when it is on the KORD machine and an impression is running, after some few impressions, operators find some parts going off the plate.

 

[ighodaro]

Hello ighodaro,


Question: 1) Do you "Image " the plates for your customers ? 2) Do the customer "Image" the Plates ?

Are they - Chinese Violet Photopolymer Plates ?

Regards, Alois

We image and process plates for customers.
We use an ECRM Mako 4x and G&J Processor.

YES, they are Chinese Violet Photopolymer plates

 

[maxon]

Hi ighodaro,
You clearly have a bad batch of plates - either a manufacturing problem or plates being stored in a VERY humid environment for a long time. Interleaf paper creased or stuck to plates indicate too high humidity.
I have never seen anything like this myself as I have only used Kodak, Fuji and Agfa plates ... it's just my two cents after 20 years spent with violet platesetters.
Get some other brand of plates for a quick test.

 

[ChrisZ]

Make a test. Expose 50% tint @175DPI. Measure it. Note the value.
Take a rag soaked with developer and rub the plate a few times with middle strength. Measure it.
Tell me what density was before/after rubbing.
Chris