6 Color Hexachrome PrePress

[Lennyr]

Hey guys,
Does 6 color Hexachrome printing require any special prepress handling?
If so what are some of the ins and outs?
Thanks,
Lenny R.

 

[CHM]

Did you aready brows the net? There is alot of info out there.
Is also difficult to explain this inhere.

 

[mazengh]

here are some clues:
1) you need profile maker or a profiling tool to generate hexachrome icc profiles. not sure if there are already generic ones...
2) you need a version of adobe photoshop that supports multichannel(cs4 and up) to convert rgb images t0 6 channel hexachrome.
3) then off course you need to setup your rip to accomodate those extra two colors... FM screening is preferable since there are no screen angles.

 

[gordo]

Hey guys,
Does 6 color Hexachrome printing require any special prepress handling?
If so what are some of the ins and outs?
Thanks,
Lenny R.

Some questions to ask yourself.

Since Hexachrome is a dead product - are you sure that you want to do Hexachrome?
I.e. use special CMY standard K plus special OG?
Or do you want to do six color process printing?
If you want to do six color process printing are you sure that adding OG to your CMYK will expand the gamut where you need it for raster images? (there are some gamut comparisons for Hi-Fi work here: Quality In Print: Hi-Fi color - 8 strategies to implementation ) Most printers that I've worked with find Warm Red/Orange and Violet to be more useful than Orange and Green.
In the majority of cases that I've experienced, with today's inks, paper and processes, a 6 color process does not add enough value to the image to make the process worth the time, trouble, and expense. So be sure you know why you are doing this.

As mazengh wrote, you need profile maker or a profiling tool to generate 6 color icc profiles and you will need to make sure your workflow can work with a 6 color process. Depending on how much work you do, you might find that building extra channels in PhotoShop to be more cost effective than using an ICC profile.

You can do CMYKOG with standard AM screens because the extra colors use the screen angles of the "missing" color. I.e. O uses the Cyan angle and G uses the Magenta angle since you wouldn't have O and C or G and M printing together anyway.

If you're using R and V then FM is a better choice of screening - but you still need to confirm that you RIP's FM screen set has unique patterns for the extra colors. Although FM screens don't have angles - they do have patterns. If you don't use a unique pattern for each color you run the risk of losing some gamut and seeing artifacts. You would also need to make sure that your system is FM capable and learn to work with FM screening.

You will need to make sure that your proofing system can work with the expanded gamut.

The extra ink colors that you choose for the press will need to be formulated to be halftone screened and overprinted (most PMS colors do not meet this requirement). You will need to work with your ink vendor on that.

best, gordon p

 

[mazengh]

how would one formulate a violet ink that would be most suitable for such a process?

 

[Bob Peterson]

how would one formulate a violet ink that would be most suitable for such a process?

First off you would need to work directly with your ink supplier. We occasionally get requests of this nature. Here is a list of items / questions we usually require:

1. A sample of a proof or color copy of the color you want, in this case violet.

2. We need to know at position the color will be run i.e. (KCVMY)

3. What the physical properties are of the current process ink you are using (If they are not ours).

4. Whether or not the finished piece will be Aqueous and/or UV coated, and any other pertinent info.

With the above info a ink can be formulated to suit the required application.

If I can be of any assistance please drop me a PM.

 

[rich apollo]

here are some clues:
1) you need profile maker or a profiling tool to generate hexachrome icc profiles. not sure if there are already generic ones...
2) you need a version of adobe photoshop that supports multichannel(cs4 and up) to convert rgb images t0 6 channel hexachrome.
3) then off course you need to setup your rip to accomodate those extra two colors... FM screening is preferable since there are no screen angles.

Photoshop will allow you to create the files - but no other Adobe app will support the resulting images.

Take a look at this thread:

http://printplanet.com/forums/adobe/24174-multi-channel-support

 

[tmiller_iluvprinting]

Have you given any thought to using TOYO's Kaleido Inkset? Many of the advantages of multi-color printing with a four color ink set that performs well.
Regards,
Todd

 

[gordo]

Just adding to what Bob wrote -

The most popular Violets for Hi-Fi color are: 2735C, Violet C, 2592C

Normally you want to keep overprinting colors as far apart as possible on the press as this helps increase trapping efficiency. So the sequence would be VKCMY or KCMYV. This also keeps the KCMY together thus reducing washups and avoiding distorting your standard 4/C presswork.
Typically you want the extra "process" color to perform as close as possible in terms of transparency, tack, and pigment grind to its closest process color ink - i.e. cyan.

Here is an image of a halftone using Cyan ink performing correctly (AM/XM on left - FM on right)

Here is an image of a halftone using Orange ink performing poorly because it was not formulated to act as a process ink (AM/XM on left - FM on right)

best, gordon p

 

[mazengh]

so how would one use the multichannel generated ICC profile to see if a pantone color can be produced using a one of the ink combinations. i understand that trying to convert the PMS color in photoshop to the multichannel icc profile generated by profile maker will give an on screen visualization to compare the colors on screen, and check how close the lab values are, but how would u use those percentages if other adobe software does not support it...

 

[localghost]

Currently we do a sandwich in the Appearance panel of Illustrator. 4 overprint fills: standard one for cmyk inks plus 3 for RGB.

Still researching for colorproofs solution; EFI XF 4.1.3 works but not so good:
only PDF-input (no "printer driver" .ps) and need to be monitored by an operator and fix when EFI fails to resolve channels properly (job channels are messed up often).

 

[Michael Ditchett]

Hi Lenny. You could try Opaltone - Home for some other thoughts and ideas.

Michael

 

[Michael Ditchett]

try opaltone.com for some other ideas.

Michael

 

[markf]

so how would one use the multichannel generated ICC profile to see if a pantone color can be produced using a one of the ink combinations. i understand that trying to convert the PMS color in photoshop to the multichannel icc profile generated by profile maker will give an on screen visualization to compare the colors on screen, and check how close the lab values are, but how would u use those percentages if other adobe software does not support it...

Photoshop does indeed support multi-channel but it doesn't generate an on screen visualisation that bears any resemblance to the file separated by the multi-channel icc, this goes for version 5 as well, so on screen colour matching may be a problem..

According to Adobe, the calculation required to do an accurate soft proof of these profiles would take so long as to be unusable at this point in time. However, they did want to make available this conversion to multichannel separations, and didn't want to remove the feature just because the soft proofing was not there yet.

 

[localghost]

We have tried EFI XF 4.1.3 for 7/c colourproof, paper proof are OK, but no luck with PDF output. Got an unexpected results everytime with file output to PDF (softproof).

 

[danpulling]

We have a solution called Equinox that will do everything required for extended gamut printing. This includes enhancing images or converting spot colors to an extended gamut ink set.

Feel free to contact me if you want more information.

 

[michaelejahn]

The best way to perform special color separations that I have found is to use this;


Glynn Hartley

Specialcolor
ICISS - CoCo - nColor
25 Redcliffe Road
Nottingham, NG3 5BW UK
Tel. +44 115 962 6060
Specialcolor - Worldwide distributors and implementers of color separation and color correction tools

 

[localghost]

Does Equinox system have the contract proof solution? Something like EFI XF.