Creating a Stochastic (FM screen) Screen ?

[kelly crosby]

I am creating artwork using Illustrator 10 and photoshop 7 (MAC) that will be screen printed. Is there a way to create stochastic screens in either illustrator or photoshop? Maybe a 3rd party program/plugin?

I have a photoshop file of a gradient blend converted to a stochastic screen that I use in the art. But obviously i am limited and would like to create my own gradients and even drop shadows. The creator and program that created the file i have is unknown to me. But its told to me that they used a special program.

I have messed around with adding noise to a drop shadow and then converting to bitmap experimenting with different settings/techniques, but have not been able to duplicate the look. I have gotten close, but the blend/pattern still doesnt look correct.

Any help would be greatly appreciated.
thanks

KC

[Todie@adobeforums.com]

Most stochastic dots are created in the RIP, at output time.

You can play with dithered bitmap, but the midtones won't be smooth.

Check this out:
<http://www.secondglance.com/products/photospot/sales/photospot.html>

and this:
<http://www.isisimaging.com/ICEFIELDS.html>

[Stevie_J_V@adobeforums.com]

Make all the art into a Photoshop file Kelly, Index colour is the best method to simulate stochastic and gives awesome results (no overprinting and very little gain) You do need quite a few printing heads to get a good result.

here's a brief run down on how I do it, still in RGB, set the image size to 170 pixels/inch, go to image>mode>index color and you'll get the index dialogue box, turn off preview and in "palette:" go to custom.

Remove all the colour index squares by clicking and dragging diagonally from one corner to the other, this highlights all the squares and you can delete them, now pick out the amount and range of colours you'll need from the white squares, one at a time, as you click on them you'll get a colour picker and you can eye drop from the image. when you have the 2,3, 4, 5, 8, 12 colours, whatever you need, save your colour palette, click OK and turn on the preview back at the index color dialogue box, you'll now see the image as it will look in index, it may look crappy at 100% but zoom in and you'll se how the image will print, if this is what you want then click OK and we can separate the index file.

I'll run through that tomorrow if your interested.

[kelly crosby]

Todie, Stevie,
thanks for the help/suggestions. I am temporarily on another project that came up i need to complete. I will be getting back on the stochastic project very soon and will look into your suggestions.

Stevie, i just might be interested in more once i am back on the project.
Youll probably be hearing from me soon.

....."You do need quite a few printing heads to get a good result."....

I am unsure of the "printhead" situation. All my stuff gets printed in tiawan, so i am pretty disconected from that end. Sucks sometimes, it would be nice to be able to have comunications with the printer sometimes to help educate me. Is there something i should look for / ask about the printer about his print equipment?

Thanks again,

[John_Slate@adobeforums.com]

Is there something i should look for / ask about the printer about his
print equipment?




Yes... whether or not they can do the stochastic screening in their rip, in which case you don't have to do anything special, just prepare normal Photoshop and Illustrator files.

You said screen printing... silkscreen?

Steve:

So stochastic screening works OK in silkscreen? I would have thought that most stocastic would have too fine a dot for the silk.

So your method uses the dithered pixel structure of the indexed file, separating each of the colors in the table to a plate... interesting. In which case file rez would determine the dot size.

[JasonSmith@adobeforums.com]

"So stochastic screening works OK in silkscreen?"

Yes, actually it can be quite popular with screen printing. Of course they use a coarser dot for silkscreen, not the fine dot used for offset.

[Stevie_J_V@adobeforums.com]

170 pixel/per inch file size John (that's what I use anyway, some people go to 220 or finer), way too fine for screenprinting in halftone with graduated dots (45-55 line halftone is most common in screen printing), but perfect on the same mesh with index/fake stochastic, the main benefit being no dot gain because there is no overprinting and the print remains sharp right throught the run.

You don't put much ink down though so we've devised a method of putting a higly reduced (90% reducer) clear down afterwards to seal the "nape" of the shirt so after washing it doesn't look instantly 5 years old.

I've done some award winning stuff using the index method.

Lots of print heads means lots of colours Kelly, at least 8, my stuff usually comes in at 12 -14 colours.

[John_Slate@adobeforums.com]

....lots of print heads... lots of screens... one for each color.

no overprinting.

yeah but wouldn't that mean essentially kiss-fits between all plates that touch each other?

how do you avoid the need for trap?

I was always taught that silkscreening required pretty meaty traplines.

[Todie@adobeforums.com]

Some of the "heads" : ) are used as driers.

[Stevie_J_V@adobeforums.com]

And all good printers can handle "butt fit" (as in butt up to each other) rather than overprinting. Lots of trapping is for crappy machinery, lowest denominator types, I don't deal with them.

[JasonSmith@adobeforums.com]

Well if we're talking about silk screening, consider this scenario:

12' banners, double sided.

In silk screen, one color hits first -cured, then the next color, and so on. Each ink hit, the substrate has to go through UV lamps to cure the ink.

Each time that substrate goes through the UV lamps, it shrinks a little bit.

So 4 color, both sides - that's 8 times that banner is going through the UV lamps. (assuming it's only 4 color - no spots/white or clear coat)

I've seen times where an 1/8" trap was not enough for this type of job.

[Todie@adobeforums.com]

Stevie is talking about T-shirts (10-12" wide images).

(What's funny is that I've seen moire patterns on stochastic printed shirts : )

[John_Slate@adobeforums.com]

What's funny is that I've seen moire patterns on stochastic printed shirts




Certainly not a screening moire...

Must have actually been in the file (pixel moire)

[Todie@adobeforums.com]

Even if there's no moire in the image (and there could be), there could be fine lines that clash with the screen's mesh angle, and (or) the T-shirt fabric's angle.

[Tim_Lookingbill@adobeforums.com]

Jason,

You don't print off contact? I've never printed banners, but we did do some slick surface coated posters and off contact was used for each ink. Later we cured it under lamps.

[JasonSmith@adobeforums.com]

"off contact"

I dont think so, because I have no idea what that is...?

We would always have problems with different substrates - sometimes the ink just didnt want to stick.

[John_Slate@adobeforums.com]

Off contact <http://www.nehoc.com.au/training/is/08/>

[JasonSmith@adobeforums.com]

whatever it is - the site kills safari. it just simply fails to load, and takes safari down with it.

[John_Slate@adobeforums.com]

From that link:

When the ink can not be absorbed or penetrate the surface you wish to print, you can not lay your screen directly onto the surface to be printed or the design will blur/ smudge when printed.

The screen must be raised above the item to be printed by approx. 3-5mm, to create an 'off contact' style of printing. After your squeegee passes over the design area, and the ink is printed onto your item, the screen 'snaps' back upwards and the ink is left sitting on top of the item.

[JasonSmith@adobeforums.com]

Yep, opened in IE to see what it's about.

I can guarantee that's how we printed. I'd say they had the screens at least 1/4" above the substrate.

There's a lot of flex in a 96"x48" frame.