Screening / imagesetter / press problem?

[ruthndul]

We've been having this problem since a long time ago.

The black is screened to 77% - no problem
The green is supposed to be solid.
It's solid on the file and on the screen on the image setter RIP computer.

Imagesetter : Agfa Avantra 25
Press : Itek 3985 two color.

150lpi / 4000dpi

we tried to switched off the plate and see on pic #2 for the result.
The lines are still there.

Is it file problem or image setter problem or press problem ?

Thank you

 

[dabob]

You would have to attach the file for someone to give you any kind of answer that might help you . . .

 

[ruthndul]

updated with real logo on file (pic #3)

solid spot color green

 

[gordo]

We've been having this problem since a long time ago.

The black is screened to 77% - no problem
The green is supposed to be solid.
It's solid on the file and on the screen on the image setter RIP computer.

Imagesetter : Agfa Avantra 25
Press : Itek 3985 two color.

150lpi / 4000dpi

we tried to switched off the plate and see on pic #2 for the result.
The lines are still there.

Is it file problem or image setter problem or press problem ?

Thank you

Why are you imaging at 4000 dpi for a 150 lpi screen? Have you tried the file at 2400 dpi?

I doubt very much that it's the press. It is most likely the file. It might be the imagesetter but I doubt it.

 

[maxon]

You should have posted pictures of the films and or plates. Printed sheet is not relevant.
What angles is you spot colour plate ? K seems 45. Did you see artifacts e.g. banding on previous jobs ?
Off topic there's no real benefit exposing film at 3600 for your Itek ... the 150 lines screening is probably the upper limit (but ok to work at 150, though).

 

[maxon]

Why are you imaging at 4000 dpi for a 150 lpi screen? Have you tried the file at 2400 dpi?

The Avantra max addressable resolution is 3600 which also tells me ruthndull does not have much control over what's happening in the prepress/imagesetter dept.

 

[dabob]

We still need the original file to give a reasonable guess . . like an illustrator file - if its in photoshop thats probably the problem . . . but no file no good answer

 

[ruthndul]

Why are you imaging at 4000 dpi for a 150 lpi screen? Have you tried the file at 2400 dpi?

I doubt very much that it's the press. It is most likely the file. It might be the imagesetter but I doubt it.

Haven't try at 2400 dpi but will do

 

[ruthndul]

The Avantra max addressable resolution is 3600 which also tells me ruthndull does not have much control over what's happening in the prepress/imagesetter dept.

there's an option of 4000 dpi. i'm the prepress guy....

 

[ruthndul]

You should have posted pictures of the films and or plates. Printed sheet is not relevant.
What angles is you spot colour plate ? K seems 45. Did you see artifacts e.g. banding on previous jobs ?
Off topic there's no real benefit exposing film at 3600 for your Itek ... the 150 lines screening is probably the upper limit (but ok to work at 150, though).

both black and green are on 45 degree.... just realized, this might be the problem. But the green is solid, does it matter ? This problem shows on every job. I thought it was blanket problem on head #2, apparently not. Attached picture of actual plate used (cleaned, but there's a bit of black ink leftover on it) - it's a polyester plate. To me, the plate looks fine, solid, there's no line pattern on it.

 

[ruthndul]

We still need the original file to give a reasonable guess . . like an illustrator file - if its in photoshop thats probably the problem . . . but no file no good answer

original file was created in Illustrator (PDF). Vector. I can't embed any file other than JPG/PNG
I can send the file by email. pm me your email please. thanks

 

[Chasfinch]

the black is treated as 4CP and the spot defaults to K in 4CP uin most RIPS that is why you have the same screen angle. It is not the press and even the image setter itself I bet. Most likely it is the raster of the RIP. Somehow the conversion is happening - its almost like the green is 1 of a 4CP color not a solid spot.

and there is no real reason to run 4000 DPI 2400 is plenty for 150 LPI but you have to re calibrate to the 2400.

 

[ruthndul]

the black is treated as 4CP and the spot defaults to K in 4CP uin most RIPS that is why you have the same screen angle. It is not the press and even the image setter itself I bet. Most likely it is the raster of the RIP. Somehow the conversion is happening - its almost like the green is 1 of a 4CP color not a solid spot.

and there is no real reason to run 4000 DPI 2400 is plenty for 150 LPI but you have to re calibrate to the 2400.

Thanks. I posted the plate picture here. The plate looks perfect-solid, no lines

 

[Chasfinch]

Thanks. I posted the plate picture here. The plate looks perfect-solid, no lines

if the plate looks solid I have no clue Someone must have gotten the box of dots out

 

[ID13]

Is it a problem you've had with just that ink, or just head #2? I've had really old ink do something similar for me, some new ink might be worth a shot. If the ink and plate is fine, I'd check the roller pressure to the plate and the condition of the rollers.

 

[realaqu]

there's an option of 4000 dpi. i'm the prepress guy....

looks like you are using indesign to do the separations, for a 2 colors 3985, you should only use spot colors, no matter you choose 4000dpi or 2400dpi, the setting will be override in rip, this is a host based separation, so you need to calibrate yoru rip first and uncheck in rip separations

 

[realaqu]

both black and green are on 45 degree.... just realized, this might be the problem. But the green is solid, does it matter ? This problem shows on every job. I thought it was blanket problem on head #2, apparently not. Attached picture of actual plate used (cleaned, but there's a bit of black ink leftover on it) - it's a polyester plate. To me, the plate looks fine, solid, there's no line pattern on it.

actually you can see it on your rip's output window, check green plate, roaming, that ll show you if the green is sold or screen.

 

[ruthndul]

Is it a problem you've had with just that ink, or just head #2? I've had really old ink do something similar for me, some new ink might be worth a shot. If the ink and plate is fine, I'd check the roller pressure to the plate and the condition of the rollers.

No, it happens on head #1 too, you can see the pic on my first post when the pressman try to switch the plate.

looks like you are using indesign to do the separations, for a 2 colors 3985, you should only use spot colors, no matter you choose 4000dpi or 2400dpi, the setting will be override in rip, this is a host based separation, so you need to calibrate yoru rip first and uncheck in rip separations

Yes, I used indesign, the green is in spot color. I did use host based separation (not in-RIP separation) see attached screen shot.

actually you can see it on your rip's output window, check green plate, roaming, that ll show you if the green is sold or screen.

on the RIP computer screen, the green is solid, as it is on the plate.