Spot color gradients not showing correct in vector PDF - fine if rasterized

[David Hieber]

New to Affinity, long-time Illustrator user.  Working in spot colors and trying to get accurate output of a vector gradient fill but cannot unless the art is rasterized on output, screenshots attached.  The fill is 100% tint across more than half the item, then tapers down to 30%. Everytime I export as "Nothing will be rasterized" it makes a simple 100% to 30% gradient that is not true to the original AD file.  But if I choose on output to "Rasterize all" it respects the different gradient I am expecting.  

Since my workflow is spot-color, this rasterized file will not work.  I have searched but cannot find an answer.  Does anyone have a suggestion?  Is what I hope to accomplish outside of the abilities of Affinity Designer?

Thank you in advance!

[Dazmondo77]

I find there's a limitation to spot gradients, they do work, but only if the mid-points are in the centre between your chosen spot colours - the work around is to add additional gradient points, which you can move and retain spot separation, of your chosen spot colours, making sure you don't move your mid-points - I found out the hard way while working on an urgent screen print job - what a pain?!?!?!

[Dazmondo77]

So for a star similar to yours, don't touch your mid-points and all should be fine

[thomaso]

It seems to be related to this logged & tagged ('afb-4018') bug of spot colour tints:

Also this thread, tagged as 'afb-3682' & 'afb-3691', in particular this @Dazmondo77's post as workaround, might be helpful:

[David Hieber]

Okay, thank you for the info all!  @Dazmondo77 in your examples, the "midspot" I should not move is between each instance of a sent tint of a spot-color from what I can tell.  Trying this now, anxious to see results and report back, thank you!

[David Hieber]

Well I'm getting mixed results here.  I have successfully output the art as intended at the expense of changing my preferred "Tint" to "Opacity", which will work for this project, but I am reluctant to think of my work-around on a project that I do not want the background "showing through".  Also, I do not think the apparent density of "opacity" is as dark as "tint", but maybe I'm wrong since I seldom use opacity.

@Dazmondo77, it seems that using "opacity" I am able to adjust the "midpoint" to other than 50% for what it's worth.  If you were using "tint" to achieve the gradient, I would be interested in why I cannot seem to make that work over here.

[lacerto]

11 hours ago, David Hieber said:

it seems that using "opacity" I am able to adjust the "midpoint" to other than 50% for what it's worth.  If you were using "tint" to achieve the gradient, I would be interested in why I cannot seem to make that work over here.

I was going to suggest the opacity based workaround, too, and it does not seem to have any restrictions (so I can have any number of stop points at arbitrary positions with diverse opacity values), but also cannot produce a tint-based version. Also, I have no problems producing vector based gradients of any number of different spot colors at arbitrary stop positions, with or with an opacity value, but tints just do not work, unless rasterized.

So this works normally fine:

But when positioned over another object "overprints" (disregarding whether Overprint attribute is used in the spot color; the setting it irrelevant in gradients, even in spots where the opacity value is 100%), and behaves accordingly like in this PDF:

spotgradient_v1_6.pdf

As you do not want to overprint, one possible workaround would be using a hard copy of the spot color object to knock out, and then use the opacity-based version to apply the ink.

spotgradient_v1_6_knockout.pdf

I am just wondering the real-life application of such use of spot inks? Would not a tint of a spot ink always overprint, anyway?

Note that these files used PDF version 1.6, which I think is necessary whenever using opacity values of spot colors (as they require unflattened transparencies; if not allowed, spot colors are converted to CMYK).

[Dazmondo77]

Just noticed on my earlier post that the tint in the star works but simplifies?! - but I can still apply tints to spot images?!? see vid grab -

This really needs sorting 

[Dazmondo77]

Heres a vid grab of the opacity workaround - your service provider will need to support PDF/X-4 to output

[lacerto]

41 minutes ago, Dazmondo77 said:

works but simplifies?

Yes, it seems so. I can also reproduce tint based vector gradient with spots but without stops. I think that knocking out with hard copy and then applying tint with opacity stops alllow a work around that works with any intermediate stop values and positions.

[lacerto]

15 minutes ago, Dazmondo77 said:

will need to support PDF/X-4 to output

Or just PDF v1.6 or later, the production does not need to be created with PDF/X-4 standard, as long as it does not flatten transparencies.

[David Hieber]

Fortunately, we are our own service provider and plate jobs directly with our own equipment.  Using PDF/X-4 has recently become another standard we use, but most of our previous output settings were based on "flattening", although I think we could adapt all jobs to PDF/X-4 (a custom setting to keep raster resolution, etc.) but as I am self-trained and have not dealt with very many jobs using transparency overprinting.  I also do not know definitively if there are any pitfalls I should be watching for using this setting across all of our output.

It seems that using opacity and the occasional "double-object" placing a white one under the colored is indeed a suitable work-around.  It is nice to have such good software available without having to deal with Adobe's subscription or Quark's annual upgrades, however it is easier to break the Illustrator dependency than Quark's.  I did purchase Designer & Publisher last year, along with using the GIMP & Inkscape (for outlining raster mostly) I have a workflow that is exciting to move forward with, and the occasional hiccup is fine with good gentleman as yourselves to help us beginners move along.  Thanks you and May the Force be with you!