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Hi, have searched round a few posts and spoken to a few screen printing ink suppliers, as well as Epson themselves but have not found a definitive answer to this.

I have an Epson 1500w inkjet which I have been using for colour printing for other projects, in addition to printing my film positives. This prints quite well, with a dark reddish brown when held to the light, so not 100% opaque, but I understand from a previous post on here that the Epson Claria ink is UV so it doesn't need to be completely opaque, as it will still block out the light.

If this is true, then I'm not sure I understand why all black ink cartridges are needed? The argument I've read a lot from screen printers, and the answer given to me by a few suppliers, is the RIP software will take a little ink from each cartridge. But if in Illustrator you amend the image in CMYK so that K is 100%, the printer will lay down the exact same amount of ink from the single black cartridge?

Then surely I can continue to use the printer for colour images as well as for film positives?

I would say I'm generally happy with the screen stencils, and get good detail. I am printing off some halftone images on the weekend, so my guess is that this could be where the difference lies.. maybe not?
 

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I have a Epson 1400 and use the standard color cartridges, the screen printer across the street uses all black. We borrow back and forth, and I have had them print positives with the all black, and I can't see much difference from my full color black positive. The blacks are slightly different colors, but both seem to work just the same for me (using fluorescent black light tube exposure table). I like that if I want to print a color print, I can still do so...
 

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You can get decent results either way. Since you also have a need to print color, your choice is simple.

The All Black ink setups use ink made to block UV light on films. So whether OEM ink or special purpose ink, it is the UV blocking ability that matters, not so much the precise color. Though a good thick layer of ink is typically required in either case.

With All Black ink, one is spraying ink from all channels at once, rather than dumping a whole lot from just the black channel, which perhaps makes it easier to get a well controlled but heavy print--not sure. For people who have CMYK ink but don't need to do color prints, they would still have to keep replacing the CMY cartridges since the printer is going to use up some of every color every time it starts up or cleans the head or Epson needs more profits ;-). For printing only films, an All Black setup can be more economical, especially if buying ink in bulk and refilling cartridges.

I have refillable All Black cartridges in an Epson R1900. The films work fine on my metal halide unit, 25 second exposures.
 

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t.

But if in Illustrator you amend the image in CMYK so that K is 100%, the printer will lay down the exact same amount of ink from the single black cartridge?
Your printer works with RGB, not CMYK. Convert your workspace to RGB, and you should loose the brown tinge to your films.

Like NoXid said, if you are using the other colours then no problem. Unless you are printing enough film to justify a dedicated printer then it is a shame to waste a good printer with all black.
 

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Discussion Starter #5 (Edited)
Your printer works with RGB, not CMYK. Convert your workspace to RGB, and you should loose the brown tinge to your films.

Like NoXid said, if you are using the other colours then no problem. Unless you are printing enough film to justify a dedicated printer then it is a shame to waste a good printer with all black.
Ok I'm confused. Printers print colours using CMYK, can you explain why a document produced in RGB would produce a better transparency, or rather a better black, than CMYK when sent to the printer?

EDIT: just printed an image after converting the document to RBG, and compared it to the previous and yes when held up to the light I can see a glowing red where the light passes through, the new image this is a much duller brown. Whether this will make any difference to detail in the screen stencil I'll have to see.
 

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Ok I'm confused. Printers print colours using CMYK, can you explain why a document produced in RGB would produce a better transparency, or rather a better black, than CMYK when sent to the printer?

EDIT: just printed an image after converting the document to RBG, and compared it to the previous and yes when held up to the light I can see a glowing red where the light passes through, the new image this is a much duller brown. Whether this will make any difference to detail in the screen stencil I'll have to see.
Here is a segment from the Epson UK site that will explain it better than I can --
Inkjet printers are RGB devices

In general inkjet printers are RGB devices; even if they use cyan, magenta, yellow and black ink for printing. Therefore it is correct to send an image file that is in a RGB colour space to your Epson inkjet printer driver. The printer driver will follow your driver settings to convert the image data from RGB to CMYK values and will calculate how much ink, of the available inks, is needed to reproduce any CMYK value.


I am getting a good dark black from my 1500 onto film, so I don't know why you are still getting a brown hue to your film.

Check to see that your RGB sliders are all set to zero ( for black) after you have converted from cmyk. In the past when I have converted documents from cmyk ( where all the sliders where set at 100) the rgb settings have been 37,37,39 - not 0,0,0.


 
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