With Epson R2400: best inks to block UV light?

[freedda]

I'm creating digital "positives" with my Epson R2400 printed at 720 or 1440 DPI to create a "grain" in the image (and no, I don't want higher resolution). This is then placed over a light-sensitive plate and exposed in a UV exposure unit to create an etching plate.

I've been using Quadtone RIP software to create these, using Matte Black ink only. This works, except the ink is not permanent on the transparency film and smudges, thus affecting the underlying plate image.

One suggestion has been to print with color ink instead of the black. I'm wondering if anyone has a sense of which color inks might be best at blocking UV light, which is what is required for this process. It's not necessarily a case of them being the most opaque, though that might help.

Also, is anyone familiar with Quadtone rip curves creation? If so, I another question for you.

Thanks, David.

 

[Joe Lipka]

I have used the Epson R2400 to make digital negatives. I use the complete Epson inkset to make my digital negatives. I use this because I need the color to create the "blocking color" to control the amount of UV light on my prints.

 

[freedda]

Don't know how to apply multiple colors using Quadtone RIP

I use the complete Epson inkset . . . to create the "blocking color" to control the amount of UV light on my prints.

Thanks, the only problem is, I need to have a dot/grain pattern in my transparency to create the etching plates--which is different than what you do for digital negatives--and you can't get this using the regular Epson printer driver. The only way to successfully work at 720 or 1440 DPI is using another RIP, and I don't know how to use multiple colors with the Quadtone RIP software I have--I'm continuing to experiment however.

Best, David.

 

[Ben Altman]

Thanks, the only problem is, I need to have a dot/grain pattern in my transparency to create the etching plates--which is different than what you do for digital negatives--and you can't get this using the regular Epson printer driver. The only way to successfully work at 720 or 1440 DPI is using another RIP, and I don't know how to use multiple colors with the Quadtone RIP software I have--I'm continuing to experiment however.

Best, David.

Black and yellow inks have the best blocking, followed by cyan with magenta the least. If you find the calibration routine that comes with your QTR you can print out a step wedge of each individual ink on the transparency material and print that with UV (or use a densitometer) to see how each ink blocks. If you use K3 inks on Pictorico OHP it shouldn't smudge. There are various threads on QTR you can search for on this forum and there is a Yahoo user group for QTR.

Best, Ben

 

[freedda]

question about ink block power

Black and yellow inks have the best blocking, followed by cyan with magenta the least. . . . If you use K3 inks on Pictorico OHP it shouldn't smudge. Best, Ben

Thanks Ben.

When you talk about "blocking" inks above do you mean UV blocking in particular?

And all the responses I've gotten confirm that the matte black ink does smudge on Pictorico and most other transparency films. That's why I'm going to try the color inks.

Best, David.

 

[Ben Altman]

Thanks Ben.

When you talk about "blocking" inks above do you mean UV blocking in particular?

And all the responses I've gotten confirm that the matte black ink does smudge on Pictorico and most other transparency films. That's why I'm going to try the color inks.

Best, David.

Yes, UV.

Sorry, forgot you were using matte black. Why not use the photo black? If you just want opaque dots, that or yellow would be best. Is that what you are doing? If so, it's easy with QTR - I can describe.

 

[donbga]

Black and yellow inks have the best blocking, followed by cyan with magenta the least.

Ben,

How did you determine the amount of UV blocking by these inks? A UV densitometer or ny test prints?

Thanks,

Don Bryant

 

[freedda]

Yes, UV. . . . If you just want opaque dots, that or yellow would be best. Is that what you are doing? If so, it's easy with QTR - I can describe.

Ben, I also do my photo printing with this printer using matte black ink and I don't want to do the MK to PK switch, so yes, I'd like to use the color inks to print my transparencies.

Right now for QTR I'm assuming that if I want to print with yellow only, I should set the overall ink limit to 85 (leave black boost blank), than set the yellow ink limit to 100, and leave density blank. If I wanted to mix yellow and cyan, I'd use same settings for yellow and repeat them for cyan. I'm not messing with curves or linearization at this point (though for my process I'm making pretty radical curve adjustments in Photoshop to the image before printing). I'm printing at 1440 DPI "super" resolution so I can get my dot pattern in the transparency.

And after yellow, which colors would be best for UV blocking?

Thanks for your help with this, David.

 

[Ben Altman]

David and Don - I'm out of town, will reply early next week.

Best, Ben

 

[mkochsch]

David,
I'm interested in seeing if this approach works also. My understanding of the aquatint method in photogravure is that the screen is usually burn in first and at a longer exposure than the negative.
My guess is that you may be able to get higher UV blocking using coloured inks rather than just black from the Epson driver.
~m

 

[Ben Altman]

Ben,

How did you determine the amount of UV blocking by these inks? A UV densitometer or ny test prints?

Thanks,

Don Bryant

Hi Don,

I started out making test prints and adjusting the ink profiles by eyeball trial and error. I now use a 360T UV densitometer, which gets me where I'm going a lot quicker. It's not a perfect match to my Pt/Pd prints; I hope eventually to figure out those calibration factors.

Ben

 

[Ben Altman]

Right now for QTR I'm assuming that if I want to print with yellow only, I should set the overall ink limit to 85 (leave black boost blank), than set the yellow ink limit to 100, and leave density blank. If I wanted to mix yellow and cyan, I'd use same settings for yellow and repeat them for cyan. I'm not messing with curves or linearization at this point (though for my process I'm making pretty radical curve adjustments in Photoshop to the image before printing). I'm printing at 1440 DPI "super" resolution so I can get my dot pattern in the transparency.

And after yellow, which colors would be best for UV blocking?

Thanks for your help with this, David.

Hi David,

Here's a simple approach to an ink descriptor file to control each ink. It's for a 2200, so you'd need to change the printer name and ink names to match your printer. It basically removes all the black-box adjustments so you can see exactly what you are doing.


#
# quadtone curve descriptor file
#
#
# the printer name
# the curve name
# no spaces or special characters, except - or _ (dash or underscore)
#
PRINTER=Quad2200-K7
CURVE_NAME=test.txt
CALIBRATION=NO
GRAPH_CURVE=YES

#
# number of inks must be 4, 6, or 7
# the ink limits are percentages
# usually they are all the same but they can be individually set
#
N_OF_INKS=7
DEFAULT_INK_LIMIT=100

#
# Describe Usage of each Ink: K,C,M,Y,LC,LM,LK
# All Inks of Printer must be listed
#

#
# Gray Partition Information
# use ink names: K,C,M,Y,LC,LM,LK
#

GRAY_HIGHLIGHT=0
GRAY_SHADOW=0

GRAY_OVERLAP=
GRAY_GAMMA=1
GRAY_CURVE=


#
# Unused Inks
#
N_OF_UNUSED=0

CURVE_K="0;0 100;00"
CURVE_LK="0;0 100;00"
CURVE_C="0;0 100;00"
CURVE_LC="0;0 100;00"
CURVE_M="0;0 100;00"
CURVE_LM="0;0 100;00"
CURVE_Y="0;0 100;100"



This is set up to give a linear ink profile in yellow only - none of the other inks print as their profiles are set to zero. If you want to add in another ink, just change the last number in that ink's line and reduce the yellow in proportion. (If you don't balance the total ink volume, you'll get puddles.) For instance if you wanted 2/3 yellow, 1/3 cyan, those two lines would need to be:

CURVE_C="0;0 100;33"
CURVE_Y="0;0 100;66"

If you want to get into a curved ink profile it's more complicated. I use an Excel spreadsheet I developed myself. Ron Reeder's site has another method.

UV ink blocking, as I suggested in my earlier post, is pretty obvious - the farther the color from violet, the more it blocks. So magenta, cyan, yellow, in that order. You'd have to test the light cyan to see where it fits in the sequence.

Hope this helps!

Ben

 

[freedda]

Hi David,
Here's a simple approach to an ink descriptor file to control each ink. It's for a 2200, so you'd need to change the printer name and ink names to match your printer. It basically removes all the black-box adjustments so you can see exactly what you are doing.

UV ink blocking, as I suggested in my earlier post, is pretty obvious - the farther the color from violet, the more it blocks. So magenta, cyan, yellow, in that order. You'd have to test the light cyan to see where it fits in the sequence.

Hope this helps! Ben

Thanks Ben, I'll look this over and see if I can make sense of it.

A few days ago I printed some transparencies using the method I described earlier, printing in yellow, green (yellow and cyan), and blue (cyan and yellow). When I looked at the yellow under magnification, I could not differenciate (sp?) the yellow dots of ink from the underlying film, so I did not use this to expose a plate, though maybe I will try it next time.

I got varying results and even got some possibilities from the blue, which as you said, probably gives the least UV blocking.

Next time I'm going to try printing in red and magenta also.

The main issue is, I had--through a great deal of trial and error--come up with proper transparencies and exposure times using the matte black ink (except that it smudges!). So I'm really starting all over with testing these color transparencies, which is a bit frustrating, but I'm glad they are showing some potential.

Best, David.

 

[freedda]

Ben, one question (at least to start with):

What do these numbers, below, signify (especially the 100s, the 33 and 66?) and do they correspond at all to the density and limit settings for individual inks in the QTR Curve Creator tool? That's the interface I'm most familiar with.

As I said earlier, I'm setting the density to 100 and leaving limit blank, wheather I'm using only one ink or applying it to two inks (for example, using yellow and cyan to make green).


CURVE_C="0;0 100;33"
CURVE_Y="0;0 100;66"

Best David

 

[Ben Altman]

Ben, one question (at least to start with):

What do these numbers, below, signify (especially the 100s, the 33 and 66?) and do they correspond at all to the density and limit settings for individual inks in the QTR Curve Creator tool? That's the interface I'm most familiar with.

As I said earlier, I'm setting the density to 100 and leaving limit blank, wheather I'm using only one ink or applying it to two inks (for example, using yellow and cyan to make green).


CURVE_C="0;0 100;33"
CURVE_Y="0;0 100;66"

Best David

Sounds like you are using Windows? I'm on Mac... Your curve creator will work fine. Just be sure you are using a standard exposure and doing test step wedges until you can get a full black, a clean white, and even tones in between. It's not worth printing images until you have all that down.

Ben

 

[freedda]

Ben, I'm still wondering what these numbers mean and do any indicate ink limit or density:

CURVE_C="0;0 100;33"
CURVE_Y="0;0 100;66"

David.

 

[donbga]

Ben, I'm still wondering what these numbers mean and do any indicate ink limit or density:

CURVE_C="0;0 100;33"
CURVE_Y="0;0 100;66"

David.

Just to point out, since you are printing positives, these curve settings will affect the hightlights (if I'm think backwards correctly). If you are using QTRGui, you can right click on the curve name and a graph of the ink curves will be displayed which is useful to grok the curves.

Don Bryant

 

[Ben Altman]

Ben, I'm still wondering what these numbers mean and do any indicate ink limit or density:

CURVE_C="0;0 100;33"
CURVE_Y="0;0 100;66"

David.

Let's start with

CURVE_X="0;0 100;100" where X is any ink.

The numbers define what happens when the Photoshop file output is 0% (ie level 0) and 100% (level 255). So in this case it tells the printer to give this ink zero flow for level 0 (white) and 100% flow for level 255 (black). However the QTR program also interpolates for values inbetween, on a linear basis. So at 50% output (level 127) the ink flow is automatically 50%.

If we change the numbers, it changes the distribution, so for instance CURVE_X="0;20 100;70" would print at 20% for level 0, 70% for level 100, 45% for level 127, and so on.

If you want to adjust the ink profile at intermediate points, just add them, e.g. CURVE_X="0;0 20;18 40;34 60;58 80;73 100;86"

This is roughly what a typical profile looks like as at higher ink densities the dots overlap (dot gain) and block more light than you expect, so less ink is needed to get a linear response when you expose your analog material. Again, the points between the ones in the profile are interpolated in a linear fashion. You can quickly get a rough curve by trial and error printing and exposing test wedges and adjusting the numbers and printing again.

So these curves do work as ink limits and density controls on each ink, yes, but they also allow pretty much total control as you can add as many intermediate points as you like. I use 20, but that means using a spreadsheet to manage them...

 

[Ben Altman]

If we change the numbers, it changes the distribution, so for instance CURVE_X="0;20 100;70" would print at 20% for level 0, 70% for level 100, 45% for level 127, and so on.

Correction - that should read:

If we change the numbers, it changes the distribution, so for instance CURVE_X="0;20 100;70" would print at 20% for level 0, 70% for level 255, 45% for level 127, and so on.

Sorry if I confused you!

Ben