Blending with Pantone or spot colors

05 Oct 2010

Today I received an Illustrator related question from a reader that really stumped me. I didn't have an answer straight away, so I had to try certain things out to be able to offer some help. Here is the thing: If you're using the blend tool to create a blend between 2 spot colors, it seems that Illustrator turns the values in between these colors into CMYK values. Are there ways to circumvent this?

Is there a way so the blend consists of various hues of the Pantone colors, rather than CMYK values?

I guess, if it's possible to change the blend into a simple gradient going from spot color 1 to spot color 2 it solves the issue in a simple way, but what if that isn't possible? What if you blend from 2 different shapes? Because that is one of the things I would use the blend tool for. Otherwise I'll apply a gradient instead. Here is what I tried out:

Create style effect on both ends

Create a style effect on both ends of the blend, using 2 fills on top of each other via the Appearance palette. For one end of the blend you use spot color 1 as a first fill with an opacity of 0%. On top of that you create a second fill using spot color 2 with 100% opacity. Then for the other end of the blend you use spot color 1 for the first fill with 100% opacity, and on top of that you have a second fill of spot color 2 with 0% opacity. Then you blend both ends. You might need to enter specific steps for the blend…

Creating 2 fills on top of each other

When I thought of this idea, I was thinking "Aha! This is probably it!", but when I tried it out, I ended up with this moiré effect. You get to see the in between steps of the blend. Adjusting the blend, using a higher amount of steps didn't seem to help either. It even took a few seconds until the result was rendered. Something that usually doesn't happen when I use the blend tool. It didn't feel and look right.

Blending with Pantone spot colors

And so I tried something else…

2 blends on top of each other

I was thinking of trying 2 blends on top of each other, each using the same spot color in the blend but going from 100% opacity to 0% and vice versa. So here is what you need to do:

Create a blend using spot color 1 going from 100% opacity to 0% opacity. Duplicate this blend on a new layer on top of this one, and make the blend with spot color 2 going from 0% opacity to 100% opacity. This way you always make the blend with the same spot color, only you lay both on top of each other.

Blending with Pantone spot colors, create 2 separate blends on top of each other

I haven't tried this out in real life (meaning taking what I created to the printer), but I presume this will render things the way it should using only spot color values and not CMYK values instead. If anyone has a better, smarter way of doing this, please don't hesitate to share.

Comments

  1. 1 Ballookey 05 Oct 2010

    If I’m not mistaken, the only reason one would worry about the intermediate steps being CMYK is for the purpose of making separations for printing. My only experience in this regard is in screen-printing for t-shirts, but whenever a designer gave me a file like this I would create the separation for each color on a separate layer in Illustrator to make our films.

    So, in your example above, I’d have the composite art on the bottom layer, copy and paste in place to a new layer for the “magenta” separation and delete or make white everything that isn’t magenta. I’d have the magenta blending to white instead of orange. Then I’d paste the composite in place on a new layer to make the separation for the orange, this time having the blend go from white to orange.

    Then I would print the separations from the layers I created, one at a time, rather than having the computer or RIP make the seps from the composite.

    The reason for this is two-fold: first, the intermediate blend steps become tints of the Pantone instead of CMYK, and secondly, in the case of screen-printing, I like to make more overlap in the intermediate steps. By default the blend from one color to another in a Blend or Gradient is usually too perfect for screen-printing (at least at the shop I worked at!) Rather than have 50% pink at the halfway mark, I’d rather have it an extra 20% closer to the orange end, and similarly with the orange pushing closer to the pink end. This means there’s more overlap and ink density in the middle. For screen printing, it’s a little harder to get the screens to line up perfectly and having more overlap in the gradient makes sure that the shirt color doesn’t show through.

  2. 2 michael Short 05 Oct 2010

    thanks for your help Veerle this article was really helpful :)

  3. 3 Andrew 06 Oct 2010

    I just want you to know that I love your site, I usually check it every once in a while just to see what it looks like. Keep it up!

  4. 4 Veerle Pieters 06 Oct 2010

    @Ballookey Thanks for screen printing insights ;) Good advice about the overlap in the middle. Not sure if you completely read my article, but what you are describing is what I am suggesting too, as a solution: create 2 blends, each using the same Pantone color, each in a separate layer, right on top of each other.

  5. 5 Jean-Claude Tremblay 06 Oct 2010

    Hi Veerle…

    Blending two spot colors is a real pain. Hope this get addressed in future release.

    In your example using multiple fill appearance, the moiré effect you see is only on screen and cause by anti-aliasing. If you turn “Anti-Aliased Artwork” off in the preference the moiré disappears. But you also need to change something else to make the blend appears between the colors. What you need to do is select the entire blend and disable the “Knock Out Group” options.

    Their is two others methods you can use to blend using multiple fill appearance.

    1. Used Multiply on the top color and use Tint value instead of Opacity at 0%

    or

    2. Use Overprint Attributes to the top color and use Tint value instead of Opacity at 0% (Overprint Preview need to be on to see the blend)

    Using two separate Blend is also a good alternative, but sometime you can’t use this because of the complexity of the artworks.

  6. 6 ballookey 06 Oct 2010

    I did read, and you are correct - your final method is along the lines of what needs to be done. But in the final solution in your example, you’ll notice that the color is a bit thin in the middle. If you create a solid pink to orange blend, and compare it, you’ll see that the color in the middle of the layered version is thin, where the color in the solid-to-solid version is rich. This could be adjusted for somewhat by selecting the 0 opacity circles on each layer of your solution and sending them behind the 100% colored circle, but even though this results in improvement, it’s still not as dense. (this isn’t just the on-screen appearance, it comes out that way in the separations and has to do with how the edges of the transparent circles overlap the circle below)

    This represents a challenging issue for spot color separations, especially if the design utilizes something more complex than circles on a straight path. And in light of the fact that some inks are more transparent than others, I often found that these sorts of blends required a lot of hand-tweaking to get them to print as expected.

    It would be so much easier if Illustrator just simply used tints or varying opacities of the spot colors for the intermediate steps on it’s own though this might not solve all the issues a screen printer would have with the blend.

    And these days, now that I’m the one designing files to give to the printer, I avoid using blends in this way because of these difficulties. ;)

  7. 7 Richard 06 Oct 2010

    Your idea may work on screen, but may not RIP correctly.
    Here’s how I’ve been doing it since Illustrator 6.
    Gradient 1 = 100 to 1%
    Gradient 2 = 1 to 100%
    (you’ll notice I said 1% not 0)
    Set top gradient to overprint.
    Only issue is that it is blind - no preview unless you RIP the file. Now a days I FAKE it using multiply in transparency to show the customer.

  8. 8 Jean-Claude Tremblay 06 Oct 2010

    @Richard
    Richard, just turn On Overprint Preview and you will see the results of your method.

  9. 9 Veerle Pieters 06 Oct 2010

    @Jean-Claude Tremblay and @Richard thank you both for this very useful information you provide here. I truly appreciate this :) Didn’t know about the moiré issue was solvable etc. Still I think I’ll go with 2 blends on top of each other to be safe.  I’ll definitely take all of this info into account whenever I need this. Very smart thinking :)

  10. 10 Doug Downing 11 Oct 2010

    Veerle,

    I’m using Illustrator CS2. When I attempt your “spot-to-transparency” method, instead of getting a smooth color blend from object to object, only a single intermediate step appears—this is despite the Smooth Color option being selected. However, the “spot-to-tint” method works just fine, rendering a perfectly smooth color blend from object to object. (Oddly, the “dual fill” method fails whether using opacity or tint; it renders two intermediate steps.)

    I’m mystified by this. Is there a setting adjustment that I’m missing here, or could this be an issue with Illustrator CS2?

    Interestingly, the “spot-to-tint” method actually renders a smoother result than the original “spot-to-spot” version, where, on closer inspection, the steps are somewhat visible (in addition to being converted to process colors).

    FYI, there’s a technical note from Adobe discussing the “spot color blending” issue (http://kb2.adobe.com/cps/310/310443.html). It includes the following bit of advice concerning moiré patterns that may appear in printing:

    “To prevent a moire pattern when printing separations, specify a different screen angle for each spot color (for example, 45 degree Red, 0 degree Blue).”

    In creating my own example to follow along with your tutorial, I found that the top layer of my “spot-to-tint” blend was displaying a significant moiré pattern during printing, which no amount of screen angle adjustment seemed to fix. However, once I realized that I had set the top layer to Multiply, I reset it to Overprint, and that cleared up the problem completely.

  11. 11 Veerle Pieters 12 Oct 2010

    @Doug Downing I’m trying to understand what you mean with ‘spot-to-tint’ method. What exactly do you mean by that? I’m not sure really how you got this result I’m afraid.

    Maybe try Richard’s method: have 2 blends on top of each other, using overprint on both of them. You blend spot color 1 from 100% to 1% and on top of that spot color 2 from 1% to 100%. Or is that the ‘spot-to-tint’ method you are trying out? In CS4 I do see it properly previewed, but not sure for CS2.

  12. 12 Veerle Pieters 12 Oct 2010

    @ballookey

    If you create a solid pink to orange blend, and compare it, you’ll see that the color in the middle of the layered version is thin, where the color in the solid-to-solid version is rich.

    I just found an easy way to solve this issue, but involves a plug-in application called Phantasm CS. I’ve been using this great plug-in for a while, but it’s so extensive that I didn’t realize this up until now. I just wrote an article about it today. It makes this kind of blending much easier and flexible. Thought I just mention.

  13. 13 Doug Downing 12 Oct 2010

    Sorry for the confusion over my terminology. I was just trying to categorize the various blend approaches discussed in your post and in the comments.

    spot-to-spot:  Blending a spot color to another spot color. (Results in a CMYK process blend.)
    spot-to-transparency:  Blending a spot color from 100% to 0% (or 1%) opacity.
    spot-to-tint:  Blending a spot color from 100% to 0% (or 1%) tint.

    The “spot-to-tint” method, mentioned by several commenters, worked beautifully when combined with Overprint. The “spot-to-transparency” method, however, didn’t work for me in CS2, nor did the “dual-fill” (or style effect) alternative. In both cases, the Smooth Color blend option fails, and instead produces just 1-2 intermediate steps between the two objects.

    http://home.roadrunner.com/~downing/temp/veerle-follow-up.gif

  14. 14 Veerle Pieters 19 Oct 2010

    @Doug Downing

    The “spot-to-tint” method, mentioned by several commenters, worked beautifully when combined with Overprint. The “spot-to-transparency” method, however, didn’t work for me in CS2, nor did the “dual-fill” (or style effect) alternative. In both cases, the Smooth Color blend option fails, and instead produces just 1-2 intermediate steps between the two objects.

    As for the “spot-to-transparency” method, I don’t remember CS2 vividly enough, but do you still have access to the blend options via the Object menu? Object > Blend > Blend Options? Then you could adjust this to ‘Specific Steps’ and enter a value of e.g. 150. Maybe this helps? The other method, the ‘dual fill’ via style effect will probably be a features issue, something that isn’t available in CS2 yet, but I’m not 100% sure as I don’t remember anymore what is and what isn’t possible in CS2 I’m afraid.