i need help with this one

[jms]

I will be running a 5 color job 4-color process and a pms. the pms is a screen that will over print over
the 4-color process. my questions is should the pms run first or last.

 

[gordo]

I will be running a 5 color job 4-color process and a pms. the pms is a screen that will over print over the 4-color process. my questions is should the pms run first or last.

It depends.
The general rule for ink sequence is dark to light, opaque to transparent - hence the usual KCMY ink sequence and the usual PMS down first ('cause they're usually more opaque than Process colors). Also, in general PMS colors are not designed to be overprint trapped with other colors - but rather printed in isolation.
My guess is that you should run a press test, because you'll get different results with PMS down first and last. I also suggest that you speak to your ink supplier and tell them what the situation is since they may be able to better formulate the ink for this situation.
If it's a dark PMS I'd start with it first in sequence.
If it's a light PMS I'd be inclined to go with it last down.

best, gordon P

my print blog here: Quality In Print

 

[pthielen]

Run the screen last, especially if you are backing the job up. You will not have as much of a problem with the spray powder.

 

[SpeedKing]

Run the screen last, especially if you are backing the job up. You will not have as much of a problem with the spray powder.

yup.say no more.

 

[rich apollo]

It depends.
The general rule for ink sequence is dark to light, opaque to transparent - hence the usual KCMY ink sequence and the usual PMS down first ('cause they're usually more opaque than Process colors). Also, in general PMS colors are not designed to be overprint trapped with other colors - but rather printed in isolation.

I'll disagree a bit with Gordo here, at my peril. K generally goes down first, among process colors, to achieve less chromatic blacks and shadows (with proper tack backtrap isn't a huge concern). The PMS colors go down first, generally, because the first units on the press are most likely open. Pressmen will tend to run the colors all the way to the last unit so the first unit(s) can be used to pull lint and spray powder.

I would argue that it's much better to lay opaque colors last. You'll get much cleaner traps and crisper edges. For example, if you attempt to overprint black onto a metallic, the metallic will seem to "leech" through. You won't get good ink transfer onto the opaque ink.

So, to the original question - if it's a regular transparent spot color, run it first down and avoid the wash-up. If it's a "paint-job" double-hit the spot color with a screen followed by a solid. If it's an opaque ink, move the process colors forward and put the spot down last - remembering to knock out ALL elements that interact with the color, and spreading EVERYTHING to the spot color.

 

[gordo]

I'll disagree a bit with Gordo here, at my peril.

LOL!! It's OK to disagree - as long as you're agreeable.

I think your using metallic silver as an example of the problem of overprinting opaque inks is suspect since the leafing of metallic pigments (that causes the poor transfer issue) does not occur with conventional spot colors. That being said, a metallic ink designed to receive a process ink, such as the inks used for the MetalFX process, put Silver first down in sequence. But your point is taken, and I agree, in general spot colors are not designed to be overprinted or trapped with process colors. Which is why I had suggested to the OP that they should speak with their ink rep about this job. They would likely be able to formulate the ink so that it will trap with the process colors. We used to do this with spot color replacement using 5, 6, and 7 color process since the "extended process" colors - effectively spot colors, needed to perform like conventional process colors.

Sometimes answering questions like the one in the original post can reveal just how fuzzy the line is between what we know because that's how we've always done something vs what we know based on actual testing/research we've done/read about.
I think that's the case with me here.

Interestingly I can't find any information about this topic in any of the reference material I have. Not from ink vendors, press manufacturers, or print bibles thick enough to stun an ox.

Could be an interesting research project.

best, gordo

my print blog here: Quality In Print current topic: lpi vs dpi

 

[PantherMac]

Hiya Gordo! I worked in packaging for almost 8 years, most of the presses were 7 and 8-color, every deck was used...

We used to print the darker opaque PMS's last, actually (K, too), As we trapped everything into those colors (wanted them underneath, hidden). It would vary from job-to-job, nothing was set in stone (ain't that the truth!), but.. Counter to conventional commercial litho, because of the way we trapped, Dark colors and metaillics were always last (wouldn't contaminate the ink train, either.. PMS 109's a bitch to keep clean after 100m impressions). Pushing Rhodamine/PMS_185 on top of a silver looked really bad, too. You wouldn't think it would show (we only trapped 0.005'), but.. there was the pink halo staring at you from the press sheet...

Underprinting white's screwed it all up, metaillized paper had it's own set of rules too, but we added UV decks between stations and solved many of those problems. Having worked the last 4 years in the commercial market, I gotta say.. Packaging/PMS printing is a completely different animal. We used to snub our noses at those commercial guy's and all their hang ups, how 'hard' printing is.. Man, what a riot. You're bitching about dot gain? Try figuring out your angles when you have 7 PMS's.. that all trap to each other at some point (YES, 7 of them!) Dot gain's the biggest problem you got!? Must be nice....

Having worked on both sides of the fence now, I've grown to respect commercial more. I think both types of printing are very challenging, and require a great deal of talent, brains and experience to succeed. However they have drastically different challenges (the same, yet.. different). They really are completely different industries (just happen to both use printing presses). Don't assume traditional commercial-litho rule's apply (cuz they don't!) I have a great deal of respect for commercial printing and the challenges that come up. But the challenges in PMS/Packaging printing are equally hard, just very different. Attempting to compare the two is difficult at best (and I've worked 12 years between the two). It's like comparing the taste of Chicken to the taste of Fish.. Just different animals all together.

- Mac