When doing the FM screen,how to do the press control?

[Bloodsaler]

Our company prepares to do 20um FM screen this year.We haven`t done this before.So we try our best to investigate how other company does when they print FM screen.

We check the fountain solution everyday,ensure the PHvalue around 4.7-5.5,IPA contain 10%,conductivity below1800us,and the temperature around 10℃-12℃
The temperature of the press room often between 25℃-30℃,humidity ofter about 50RH。
We also check the CTP plate everyday,ensure every data in tolerance.
The blanket brand is Volcan ECO，and the bear is Mark.
We set the pressure according to the operator guide,and we intend to check it every three weeks.
We also require the operator check the density\dot gain\contrast of every print job.But not restrict them must according to ISO12647-2 standard.

What else can we do?is these above things enough?
PS:If our operator doing a FM job,how can we guide them use the proper way to control the color and qulity?

Any feedback will be appreciate~Thanks

 

[gordo]

What else can we do?is these above things enough?
PS:If our operator doing a FM job,how can we guide them use the proper way to control the color and qulity?

Any feedback will be appreciate~Thanks

1) Make sure that everyone in the shop understands why the shop is changing their print process and wants the change to succeed.
2) Make sure that the plates have the resolution to support FM (involve your late vendor).
3) Make sure the CtP has the capability to do FM (involve your CtP vendor)
4) Ask your ink vendor about the ink series you are using and whether it is appropriate for FM. They may suggest a different series based on their experience. If they don't have experience with FM, then involve them in your initial start up and learning. If they are not interested then start looking for a different ink vendor.
5) Your shop should have an existing reliable and consistent print manufacturing process. I.e. the press is not used as a color correction device.
6) Build dot gain curves to be applied to plate imaging to bring tone reproduction in line with your current printing.
7) Optionally, fine tune your proofing so that it reflects the extra gamut you'll see with FM
8) Make FM your standard screening - not an exception for special projects.
9) If you have more than one press/press crew - choose one to be your pioneers and champions of FM printing. They can then teach the other crews.

Most of the problems with FM screening are print shop culture - not the technology.

best, gordon p

 

[Bloodsaler]

Thanks gordo.
Most of the above things we have done,we gathered every fingerprint data,created TVI curve,update pringergy to 5.0 etc,the else thing we still working on it.
As you mentioned,most of the problems with FM screening are print shop culture,actually it is.The most difficult part in our plan is the press operater himself,and the cooperate of every related department.
maybe in hardware,we can up to a FM available level,but we can`t promise all of our stuff know FM screen enough.
I plan to test the FM screen mix with G7 theory,i think it helps to remain the gray balance.
Does it help?
for our oscillating ink roller doesn`t have any cooling system,so we plan to measure the temperature of the ink between the roller when the press during production.

 

[gordo]

I plan to test the FM screen mix with G7 theory,i think it helps to remain the gray balance.
Does it help?
for our oscillating ink roller doesn`t have any cooling system,so we plan to measure the temperature of the ink between the roller when the press during production.

20 micron FM is more stable on press than 133-300 lpi AM/XM screening. It has a similar stability to heavy GCR separations, so yes it will help maintain grey balance. More importantly it will help maintain presswork color aligning to the proof color.

The important thing is ink and ink transfer. FM screens carry a thinner film of ink on the halftone dots for a given solid ink density and tone compared with an AM/FM screen. So, your fount solution should not be too aggressive since it can overcome the ink film. Your ink viscosity should not be to high or stiff or you will get poor transfer. The dots will dry slightly faster than AM/XM dots.

It sounds scary - but in reality printing with FM 20 does not require anything more complicated in set up and process control than 175-200 lpi AM/XM screening does. It's just that if you are out of control, 175-200 lpi AM/XM screening is more forgiving.

best, gordon p

 

[ar17]

When doing the FM screen,how to do the press control?

we used to print FM/20um using prinergy(stacatto) and ts3244 with hedielberg web and sheetfed offset. you'll be surprised that it is more stable than am screening. you're only concern is when customer wants to do color adjustment on press. if you have a very good proof and press match with no last minute customer press-color approval, fm screening will be great...

 

[rich apollo]

FM screening is just ink on paper. Once they've tested it, the pressmen I've worked with have ended up preferring to run FM screening.

I have had a tough time getting, and maintaining gray-balance with FM screens, however. That and increased piling are the only drawbacks I've found.

ISO 12647-2 will only be partially applicable. You can hit the solid and overprint colors, TVI will be VERY different. You can control it with plate curves. You will HAVE TO control it with plate curves. Print contrast numbers may, or may not, apply.

FM screening puts more pressure on PrePress to keep things consistent. If something is wrong, FM screening really shows it - you can't hide flaws in FM screening.

 

[gordo]

To expand on a couple of points in Rich's post.

Presses do not know whether you are printing with AM/XM or FM dots. Piling with FM screening, if it occurs, is almost always seen on heatset webs not sheetfed. Generally the cause is that the inks (and print condition) that work with 133-150 lpi are not suitable for screening that is the equivalent of around 300 lpi. If you increase an AM/XM screen to 300 lpi with the same press condition you'll see the same piling issue. It is an issue with dot size relative to ink condition not AM/XM vs FM. (This has been confirmed by GATF tests)

I haven't seen any trouble achieving grey balance with FM screening (but I have not used G7 methodology to do it). If closed-loop color press-side controls are used that reference grey balance relative to solid patches in the color bar to make ink key moves - they can sometimes be "confused" because the SID moves do not affect the grey balance the way that the software expects it to do. Same thing can happen with systems that measure the live image area of the press sheet.

Like any change in the print manufacturing process - some printers will struggle and others will wonder what all the fuss is about.

best, gordon p