Invert colors in Illustrator

[Sbrem]

I have an image of a wooden board, various shades of a spot color black, vectors. Normally, this image is printed on light gray shirts with black ink, and looks fine. We've also done it on black shirts back in 2014, but that was a Photoshop file with 2 spot whites, one for the heavy text, and the other for the halftones. We vectored it after that. When I open the vector file, the various shades are of Spot Color, Halftone Black we named it. The colors won't invert (Edit/Edit Colors/Invert Colors) getting a message that Global Colors, Gradients, and Patterns won't invert. But, I choose Convert to Grayscale, then invert it, it works. BUT, if I try to assign it to a Spot White (so I can print a sep for it) all of the shades turn to 100% Spot White. I'm trying to avoid manually inverting each shade in Illy (50+ shades), and I can do it in Photoshop, but I'd really like to know if there is a way to do it in Illustrator. Thanks in advance everyone...

Steve

[Dottonedan]

Taking a random gradient, and trying to convert all of it at one time is the hard part. Each white end, be it negative or positive would need to be changed individually.

The only way I can do it, is to work with the blends (as all one unit).

Fist select all and make a copy to be saved as your original and lock that down. Move that layer to the bottom so that you always have your original. Hide it (turn eyeball off).

Now with the first copy,
1, Select all, Duplicating the entire image again, moving that to a top layer, lock that.
2, Then select, all of the bottom, unite, as a solid spot color white (change it to pink or something so you can see what’s happening in Separation Preview). keep that at the bottom.
3, Take the top grouped item and convert to grayscale, Then invert. It will give you that message, but piss on it. Do it anyways, and then for that item, go to Transparency and change to Multiply.

Duplicate that again, and again, (invert colors) that black the other way. This to me, is essentially making how a multi channel spot color greyscale seps (from photoshop) is placed and linked like The DCS2 eps does. You can assign spot colors.  The fact that they are multiplied, gets rid of the process white...and becomes transparent. Set one over the other and it works. I also assigned each to overprint and told the base to overprint at bottom. You can though, tell that black to just knock out.

The tricky part is getting a good overlapping sep of one color to another. (if blending a black over a white) intending to get some grey in there), I don’t know if at the beginning, you can simply take off of the duplicates and adjust the blend to extend over the other a little). I mentioned last week some time pertaining to knocking out dots and interlocking. The beginner "straight up duplicating blends and reversing the blend and letting each knock out of each other" (is not a good separation). It leaves that neg white gap in the middle to show. In those cases, you would have to apply more gain on one or the other.

[Dottonedan]

Example image.

[Sbrem]

Here's the image, there are no gradients, just individual vector shapes. I'm wanting to invert it to use as a white base (instead of a solid white). It's all vector. In Photoshop, it's a piece of cake, and I will probably go that route to save time, but I was thinking that Illustrator should be able to invert it, but simply won't, easily anyway.

[Dottonedan]

Ends up all raster but done in Illy.  I did also beef up the base a little so it should be able to run up underneath the black a little to create good grey without showing much shirt so thru.

[Dottonedan]

How did that work out for you?  I know it’s basically the same thing as going into Photoshop and doing that.  I don’t see a way of keeping it vector (all of those segments of shades) and converting that all at once without going that route of converting to raster. There might be, but it might be too tedious in the end.

[Sbrem]

I finished this morning. I lifted the gray shapes and put them on a separate page, saved it, and opened in in Photoshop. Then, I inverted it and saved it as a spot channel in a RGB .tif, imported into the Illustrator file. I placed in behind the gray wood, marked the wood to "overprint", sent the seps to a laser printer, and Voila! Two hours of on and off thinking, then ten minutes to pull it off. I also beefed up the base to avoid any gaps. I still think that Illy should have been able to invert it, but it is what it is.

Steve