Polymer plate Ai file prep

Dear gorgeous letterpress community-

Hopefully you can help me w/ a relatively easy issue I’m having. I’m brand new to letterpress & what little I do know, I’ve had to teach myself. I just finished my first Illustrator files to send off for my plates. I used various vector graphics from istock. I set the colour as CMYK spot colour 0,100,100,0. Apparently, there were many layers & the people making my plates had to go into Illustrator & fix all my files. She explained to me how she did it, but I am so confused & have no idea. I need to know & understand what she did so I know better the next time. Below is her email:

First of all I check the pdf in Acrobat - Advanced - Print Production - Output Preview. 
Here you can check off the spot plates and see what is left over. I then would open it in illustrator and highlight those particular images and change their elements to be a spot colour matching the rest. In the case of your plates some of the images were quite complicated and had layers of different lines so this took a little more attention to get each element perfect!

Can someone please clarify for me what to do in Illustrator to avoid this problem in the future?


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You said you set your art as “CMYK spot colour 0,100,100,0”.

Forget about the spot part of that, it doesn’t make sense. Set your document colour space to CMYK.

Your art needs to be all in 100% K.

CMYK stands for: Cyan, Magenta, Yellow, Black.

Black is K because it’s an old acronym for Key Plate. Just remember that it means black.

All your art should be black (100% K) because platemaking is a photographic process. The light burns away everything in the plate except your art, because the black blocks the light. If this is confusing, go online and find a video about screen printing — it’s a very similar process, but with more online videos.

Hopefully all your art is vector, including the istock stuff. If it’s not, then redraw it or auto trace it.

I would suggest the following:

1. Get everything onto one layer, using your layers palette. There are a number of ways to do this. Look it up in help or on the Adobe website.

2. Select all objects (Command-A). If the objects have strokes, you might as well expand the objects using Object>expand. You might as well also merge all your art in the Pathfinder palette. Open this palette and select merge. It will make your file size smaller because it removes all the bezier curves that are underneath other parts of the art, and hence non-printing. (The problems with iStock art are: 1. it’s stock art and 2. it’s poorly made.)

Then you convert all your selected objects to the colour you need them to be. Which is 100% K.

3. Go back to your colour palette. There’s a little arrow in the top right corner. Select that arrow to get a drop menu. Now choose “Select all unused colors.” Do it, and throw the selected colors into the trash.

You should only have the colour left that you need. Except there’s a bug in some versions, good luck with that.

If you can’t remove a non-100%-K colour, you may have to click around to find the offending bit. Sometimes it can be a stray dot — to find those, select Command-Y (outline view) and look for stray irrelevant bits and delete them.

4. You should be done, although you can check your outputs in Acrobat to confirm. But that’s too much to talk about here.

Otherwise, you can save a lot of production time by building your files diligently, and in as few colours as possible.

Also, go and get Gerald Lange’s book.