Trapping with WB/DC

[ZooCity]

I've bumped into a quandry on certain WB jobs- butt reg is showing hairlines between spot colors.  I'm so used to butt registering all my seps, except for plastisol underbases which get a light choke, that I'm loathe to start trapping at all and fearful of colors mixing and blending where they contact. 

What's SOP for those doing WB/DC and spot colors?  I've seen it as an issue mostly on items like baby ribbed onesies where you are inevitably printing at higher o.c. due to the shoulder lap seams, etc., so that's definitely part of it but I'm curious what others are doing here.  The danger with trapping is that, even with a full black key covering for example, if the under colors are dc and have a degree of white in them you're gonna get a grey edge to the black. 

Follow up ?: for a DC ub with WB or plastisol on top, what's a typical choke?  (keeping in mind, of course, this is relative to PPI in raster files or size of the vector shape you are stroking onto)

[patfinn]

we do some very few and far between, if your printing black with other colors you can get away with it. the most we did was about .3 of a stroke on anything. def dont want to do it with white very often either, especially with white and red. when your printing like colors. light gray dark gray you can get away with a little more here and there. as anything in our industry it depends on many things in your own shop. but do some testing and see what you come up with!

[Dottonedan]

This brings up an interesting point.  So,, I know you've got your shop pretty on point so this is an example of when using this method, everything really needs to be on point in each part of the process.


The reasons for seeing a hairline are typical when printing plastisol. On a garment, the substrate is more forgiving as well as the fact that the inks are thicker on the garment and hides some of this as a result, unless the processes in the shop are really out of control, it's not that noticeable.


Here, with waterbase or discharge, your dealing with what needs to be tighter (on point) registration, closer off contact, etc. Basically, because it's as if similar to printing flat stock. The inks are thinner and require close tolerance printing. Films need to be more on point. This is where I see some issues.


Most of us use these digital printers for films. I believe that the registration can be one when aligning them up, but off on these when looking at (butt to butt) printing. Take a spot color sep that knocks out of another solid color and line them up on a light table.


If printing a navy solid knocked out of a dark red solid (on a white tees for example), I'm thinking that you can see a hairline negative space that will let your shirt show through a tad. This would never bee seen on plastisol as the inks would spread and hide this.


This is just another good example of how things/processes change when using different methods of printing.


As to how mush spread to use, I would think that what Paffinn said would be a good starting point. He's been printing waterbase and discharge for a good while now. .5 might be too much. Not much is needed I'd think. Just something a little more than nothing to help fill in that gap and not blend with the other colors so much.

[ZooCity]

Really good point Dan.  We have a pin lock system and every film hits the light table.  With inkjet output, nothing is ever perfect it seems.  Many of the films i align are off a hair due to the printer.  So there's a problem from the get go, one that has been hidden by plastisol gain.

Thanks pat, I'll try a very small spread on the five color, spot color I have coming up, see what happens.

[tonypep]

Printed today. No choke no trap. Very minimal dot gain. We always but fit discharge but will do it for a DC UB. Four screens no base no flash

[tonypep]

And big suprise I forgot attachment!

[Dottonedan]

Tony,


Just a quick questions.  What are you printed these films out on?  Wondering if your getting these good results fm just a digital film printer like an epson.

[jasonl]

And big suprise I forgot attachment!

Are those all single strokes?  Which white is that?  It looks great.

[tonypep]

Yes single stroke this was 2K pcs. CCI white. Epson 488o

[inkman996]

Tony would you say the larger format epsons can handle film to film registration better? Reason I ask is since getting tri-loc and using epson medium format printers like the 1400 or 1430 I now see loss of registration on the films when on the light table. Most notably on the longer seps, seems anything over about ten inches starts to lose registration vertically. If it is really bad I split the difference when aligning and let dot gain handle it. But I think thats  a bad idea on things like 4cp. I would like to know if the larger format printers handle the longer separations better?

[tonypep]

I've never used the midsize ones but it's odd you say that. On the 4800s and 4880s I've never, ever seen that. Used to see it with thermal but thats pretty much outdated tech

[inkman996]

I've never used the midsize ones but it's odd you say that. On the 4800s and 4880s I've never, ever seen that. Used to see it with thermal but thats pretty much outdated tech

Believe it or not its bad enough a few times I had to reprint films.

Just trying to build up the argument for the owner and the reason to step up and get a larger format printer, the old r1800's never had that bad of an issue but since they been extinct and the newer epsons available like the 1400 or 1430 its worse.

[ZooCity]

I see the film length issue once in a blue moon and have to toss a film and reprint. I'm sure a 7880 or 9880 does somewhat better on this, it would have to.   Accurip has a feature to comp for this actually.

I see more frequent issues with just the output itself not actually butting up properly, even left to right, in the vector file though. This is random and not a consistent thing at all.  I think that's more of an Adobe>RIP>film deal though.  Been running that fixxons wp (microjet, I think like a dozen people sell the same thing under different names) for quite some time now and it clearly is not the best film out there but a good daily output film.  I have all linearization off but maybe could stand to increase the droplet size just a little.  I'm a tiny bit old school in that I keep a selection of kimoto pens in the darkroom and will hand touch up films where needed when I'm in there and see a problem.

Tony, it looks like your getting the right amount gain that I would expect to butt everything up. It might be a pressure thing on my end.  Printing DC manually is a tough go and fatigue is a definite factor. 

[Dottonedan]

I commented on this same issue a few days ago somewhere.


The random results may be due to the time of day your printing out film. If for example, you start to print films first thin in the Am and your in a cold area, the first few sheets of film will be more rigid, as the printer warms up it becomes more accurate or the film relaxes etc. so on a 7 color job first thing in the am, you may get a slight distortion.


The longer the image is) or further distance from side to side or top to bottom, the more noticeable it is.  A chance to improve this is to wait till the room and equipment warm up a bit and run them at that time.  View your butt to butt seps first thing in the AM and print the same thing again at the end of the day and you may see the difference. At the end of he day, you may have closer or tighter butt registration on all.