Printing plate requirements

[Kaoticor]

I appreciate any input you all might have on this:

We might be changing our brand of printing plates in the near future. We use a CTP process for our lithographic plates. Our management wants to know: what are the standards for a printing plate? What should a printing plate be expected to do? Sorry if that seems like an uneducated or dumb question, but other than "it needs to be able to print", I really dont know what to tell managment for a recomendation. Trying to see if I can learn a little bit more about this.

Example: for a printing blanket, some standards to go by are durability, low piling, good release, and of course good cost, etc...

What are some things you all would have as a standard for your plates? Thanks again for your thoughts

[chevalier]

Durability (number of impressions), costs per plate, cost per liter of chemicals, refill rate of chemicals (how much chemical utilized to process X number of plates), user maintenance required (plate imager and plate processor), and speed of exposure.

There are two plate technologies out there. One uses violet light to expose the plates and the other uses infrared (thermal) light to expose the plates. Both plates technologies have strengths and weaknesses.

I have used both technologies from different vendors (Fujifilm, Kodak, Agfa, and Heidelberg [resells Agfa plates]). I highly recommend Fuji LHPJ (thermal) printing plates for reliability and stability.

[Kevin@Kodak]

I appreciate any input you all might have on this:

We might be changing our brand of printing plates in the near future. We use a CTP process for our lithographic plates. Our management wants to know: what are the standards for a printing plate? What should a printing plate be expected to do? Sorry if that seems like an uneducated or dumb question, but other than "it needs to be able to print", I really dont know what to tell managment for a recomendation. Trying to see if I can learn a little bit more about this.

Example: for a printing blanket, some standards to go by are durability, low piling, good release, and of course good cost, etc...

What are some things you all would have as a standard for your plates? Thanks again for your thoughts

I think the better question is what do YOU need it to do? Your prepress and pressroom requirements will drive the selection of a short-list of products to choose from, and then you can have an in-depth look at the tradeoffs versus total cost of each solution (total cost, not just plate price).

A few of the major areas to consider are:

1) imaging technology and compatibility with your CTP device (violet or thermal, plus is the media supported on your CTP by your CTP vendor?)

2) imaging speed / throughput on your CTP - will it be sufficient for your productivity requirements

3) resoluiton - does the CTP/plate combo support the maximum screening you need?

4) processing - is the plate compatible with the processor you have, or will you need to buy a new one? Does it even need one (i.e. non-process), or can you get it included in the plate contract?

5) run length on press - this varies CONSIDERABLY from site to site depending on your pressroom conditions, so you might have to do a press test to be sure, especially if using alcohol substitutes or UV washes on press. Does the plate require baking to achieve your run lengths (cost/complexity consideration)?

6) press characteristics - probably requires a test in your specific conditions unless your needs are very "vanilla": ink/water balance latitude, speed of roll-up and full density, dot stability throughout the run, what ink/fount/paper/blanket conditions you're using, etc.

7) Total Cost Of Use - when EVERYTHING is considered, what will it cost you to make a plate? (plate price, chemistry, equipment, power, water, chemistry disposal, labor for cleaning the processor, make-ready / pressroom waste differences between plate types, etc.)


Each vendor should have a couple different types of plates that are suited to different printing environments and needs, as well as price points. A short discussion would normally allow them to focus down on one (maybe two) plates that would be most suitable from each vendor. I'm glad to help you do that for Kodak plates if you like - let me know.

Kevin.

[maas]

Cant add much more other than also conisder if your potential supplier offers consignment, technical assistance and guaranteed supply

regards
Maas

[ngocdung93]

One more optional supplier of CTP thermal plates: Mylan Group
Contact: customerservice@mylanprintingmedia.com

[Kaoticor]

Thanks for the feedback guys, appreciate it.

[rich apollo]

Kevin pretty much covered the bases. You and the potential vendors will need to conduct pressroom chemical audits. Different plates will react differently to fountain solution, blanket wash, plate cleaner, scratch remover, et cetera.

Your workflow will have some methodology for testing focus and exposure. You can learn a lot from viewing those test patterns under a scope (75x-100x). That's where you can see if the plate/platesetter combination will meet your screening/resolution requirements.

Kevin mentioned the imaging speed, which is tied to the power requirements at the surface of the plate. Pretty much any plate (thermal) is capable of screening at whatever resolution you want, or need. You may, however, have to slow the platesetter down considerably to obtain the laser power necessary to get there, though. I know of one plate/platesetter combo that was certified to 10µ, but with some digging I found that the platesetter had to slowed to 40% speed to get there. That's not the kind of thing that is widely publicized.

[Kevin@Kodak]

Kevin pretty much covered the bases. You and the potential vendors will need to conduct pressroom chemical audits. Different plates will react differently to fountain solution, blanket wash, plate cleaner, scratch remover, et cetera.

Your workflow will have some methodology for testing focus and exposure. You can learn a lot from viewing those test patterns under a scope (75x-100x). That's where you can see if the plate/platesetter combination will meet your screening/resolution requirements.

Kevin mentioned the imaging speed, which is tied to the power requirements at the surface of the plate. Pretty much any plate (thermal) is capable of screening at whatever resolution you want, or need. You may, however, have to slow the platesetter down considerably to obtain the laser power necessary to get there, though. I know of one plate/platesetter combo that was certified to 10µ, but with some digging I found that the platesetter had to slowed to 40% speed to get there. That's not the kind of thing that is widely publicized.

Thanks Rich - good additions too. I wouldn't agree with your statement that "pretty much any (thermal) plate is capable of screening at whatever resolution you want, or need" though. For most printers that's true, because you're not going above 200lpi. However, if you're doing FM or >200lpi the range of suitable plates is much smaller. Each vendor will have an option of course, but not every plate will get there (consistently). Also beware that at the finest resolutions you'll get shorter run length on many plates, because fine dots wear faster (as a percentage of their size).

You're right about many CTP's dropping to half-speed for the highest resolutions - but not Kodak devices. It's not actually a power issue though - in reality they cut the power in half instead, by using only half of the imaging swath. Essentially, they can't control the uniformity of the full-width beam (all channels) good enough to get uniform performance at the highest resolution, which would cause banding.

When buying your CTP, make sure you get a written quote of the productivity at the HIGHEST resolution you plan to use (even if you don't use it today), with the exact plate type you plan to use. There can be a 50%+ difference depending on the machine/plate in question.

Kevin.

[Kevin@Kodak]

Just a suggestion, but make sure that you try and get in contact with some customers who have used the product you are considering and talk to their prepress and pressmen. Its amazing how many holes you will find in a product description when you start talking to the people who use it. The plates we use were rated for long life runs (500k impressions) without baking - yeah, they don't do it.

As a vendor, I'll actually second that. Just make sure that the customers you talk to are using the plates in a similar way, with similar press conditions and screening.

"Run Length" is a very difficult specification to put down on paper because press conditions affect performance so much. We try to use numbers that an "average" printer can achieve with the plates, but there are always exceptions (both higher and lower).

Newer-generation plates generally won't be as variable as older ones though... mostly because the trend in plate technology is to have better press chemical resistance without baking, and that's one of the biggest variables today (alcohol subs, blanket washes, etc.). Plates like our new Trillian SP are largely unaffected by those variables though.

Kevin.

[rich apollo]

The plates we use were rated for long life runs (500k impressions) without baking - yeah, they don't do it.

Pressroom conditions have a HUGE effect on run length. You can significantly increase the plate life with some adjustments to your fountain solution.

Thanks for the clarifications, Kevin.