Plates not holding ink

[jrrowellprinting]

I have been online researching what I thought was a unique issue that we had never seen before here, but alas I found an old post from December 2009 that was posted by myself:

http://printplanet.com/forums/prepress-workflow-discussion/20370-plates-not-holding-ink-properly

Let me outline what happened this week: For some reason our suppliers for chemicals for our processor no longer supplies Agfa chemicals, so we switched which required an extensive cleaning of our processor. Once we had the new chemicals in the processor plates came out looking great, but once on the press they refused to hold ink. So we were told that we did not clean it properly before changing the chemicals and that we were to use Muraitic acid to clean it. So we did that. The plates came out looking fine but alas they held even less ink than before the muriatic acid. My question to you is this:

Am I crazy to think that switching chemicals has put a spotlight on the possibility that our image setter is having the issue? and that the Agfa chemicals may have been more forgiving? That would explain why cleaning with the acid produced worse results since possibly there were still Agfa traces left in the machine.

Oh I also need to tell you that an "info" message has appeared on our image setter that states: "The air filter is used & must be replaced. There will be a loss of recorder quality due to dirty mirrors if this occurs over a long period of time". Now back in 2009 a tech came out and told us the mirrors were fine but that was over 2 years ago. We have ordered a new filter but it will be quite some time before we receive it. We are currently unable to plate and print and have been for 4 days since we all thought it was a chemistry issue but we have tried like heck to do everything to get these plates to take ink unsuccessfully.

If anyone thinks this might be our mirrors, can anyone tell me how to clean them?! Getting a Heidelberg tech out here would take days and frankly we can't afford it!

Or if anyone thinks it might be a chemistry issue, let me know what I can try since we are out of ideas!

 

[VladCanada]

If you develop AGFA LAP-V plates with non-AGFA developer -> expect some troubles.
AGFA, Fuji and Kodak use the same chemical principle of "silver" plates to process, but use some different chem additives.
In your case unexposed parts of image after development, diffusion and wash-off processes still have some extra layer on top of receiving layer (which absorbs silver-halyde particles and creates ink-acceptable image).
Use a perfect match plate-chemistry pair from the same company.
That's not a film process where the film is more tolerant to not original chemistry, for instance: AGFA - Kodak is pretty good match pair, but Fuji film needs Fuji chemistry for the best result.

 

[jrrowellprinting]

Currently going back to Agfa Chemicals

Currently going back to Agfa Chemicals

Thanks for posting your reply.

Just thought I would update. We decided that since we have been down we would switch back to the Agfa chemicals to at least hopefully get something printed.

What we have figured out so far: The new chemicals needed a different processing and exposure time that what we had for Agfa, and to change that would be like moving mountains since Heidelberg has no one in the area to service our prosetter and would charge $1000 just for traveling expenses for the tech to come out here. So we are switching back. We have ruled out any issue with our image setter since we had a company down the road image a plate and we brought it back here to process and the plate still did not hold any ink.

So we are waiting patiently as we switch the chemicals yet again to see if switching back will get us back to printing.

Thanks and I will post back again when we figure it out. The thing is another company switched to these same chemicals with some of the same issues, but it has since worked itself out for him, it did not work itself out here.

 

[SteveAgfa]

jr:

As Vlad said, the chemistry for your LAP-V plates are an integral part of the system.

That said, it is also important to deliver proper exposure. Follow your manufacture's
instructions for cleaning your mirror, as that too will contribute to poor migration of
the silver to the substrate. Between returning to the proper chemistry, and a proper
exposure delivered to the plate, I suspect you're on the right track.

Regards,

 

[Green Printer]

We have used the violet lap plates since 1998. Anytime the plates did not take ink it was always chemistry.
The gum bath enables the silver coating to accept ink correctly. Infact Agfa sells an additive to help with ink reception. Don't waste your time fooling around with other chemistry.
It is possible to make many of the availables gums to work with the lap plates. Out of courtesy to Agfa that will remain quite.

 

[jrrowellprinting]

Back on Track

Back on Track

Anytime someone tells you that changing the chemistry should be seamless... is completely worthless!

We are back to Agfa chemicals and plating and printing happily now.

Thanks for your replies. I was told that the issue is not having a Heidelberg tech here to adjust the image setter to the proper settings and not having the proper speeds set in our processor for the new chemistry is where we went wrong. But we were told it we didn't need all of that to begin with.

Thanks for your input.