Silk Screen and Halftone dots

Question

What is the short answer to, "Can Illustrator allow the user to control the size of halftone dots?" Just to be clear, for silk screen, the dots must be course. I have read several posts on the subject and still there is no definitive answer. The PPD file has been loaded. The document is a CMYK. In the print menu the separation menu has only very fine settings available (The lowest is 56 lpi/300dpi) which if selected makes very little to no difference in the dot patterns.
     Just to reduce confusion, often a silk screen printer will try to get two colors for the price of one. The simplest example would be to get Black & Gray with one screen. If I set the Gray to 50% and the Black to 100%, still no change. If I use spot colors like PMS Cool Gray and Black, no change. Moving the files into Photoshop may work but fundamentally speaking PhotoShop in my opinion is for constant tone images or Photos, and it seems counter productive to add in a extra step (and software) to the work flow.
     I like to stick to the old K.I.S.S. motto. Keep It Simple Stupid. In this case less is better. Other software packages make this task a no brainer. I like Illustrator and have invested hundreds of hours learning and promoting it's virtues. When I was asked by a local shop how to do this task, I responded, (Oh I'm sure its just a setting that needs to be set.) Well, not so. So, Can I do this or do I need to tell my associate to keep using CorelDraw! 7...

Answer 1

Wow, you guys have been having quite a conversation while I was sleeping!  I'll address a few comments here and there:
A silver disc with a 25% purple halftone will just look silver with a purple hue.
That's exactly the effect I'm after - I'm hoping it will look cool.
Also keep in mind that any time you have a screen printed halftone you
will be able to see the little dots that make up that halftone.
Yes, I know.  As idea-starters I have been looking at CDs/DVDs that I own that have been silkscreened, and I decided to pursue a semi-transparent halftone because I like how it looked in someone else's design (in that case it was blue rather than purple, and I don't know what percentage coverage, but I'm trusting my imagination to take me the rest of the way).  That halftone was about 42 lpi, and I could even see how small text looked on it, so I would be happy with anything at least that fine or finer.  I also ran across a label whose whole background was a halftone gradient between completely tan and completely black, and all the "foreground" elements like text and logos were the clear silver - the halftone was only 25 lpi, no doubt to try to improve the quality of the dots in the low percentages.  Whoever designed it probably thought it was nice-looking, but I didn't - not only isn't the gradient very smooth, but although transparent text on the black or almost black areas were easily readable, to read the stuff that is in the mostly tan areas I had to tilt the disk to reflect more light.  Frankly, the only halftones I really like in the examples I have seen are ones with only one color - when they try to blend two inks by making the screen angles different, it doesn't look as clean to me.  Plus, I simply like the look of utilizing the silver - it's an effect unique to silkscreen on CD/DVD disks, not found in offset labels or silkscreen on other materials.
You also mentioned a custom white.
Not really a custom white - the replicator's literature about what is included with replication said "silkscreen in three colors (counting white) or offset" - actually at the moment I can't find where it said "counting white", so perhaps I can choose my own three colors, but whatever I read originally seemed to say that one of my three colors had to be white, so I was designing based on that assumption.
I'm using spot colors for everything in my Illustrator file, so it should be very clear to the replicator what objects should be what color.  I really wish the swatches in Illustrator would actually control the color of the instances that use them, like swatches and styles in InDesign work, but unfortunately when I experiment with changing the swatch to a different shade, I have to then select each object one at a time and tell it to use the swatch again - cumbersome.
I also would name a background color "silver of the disc" just so there cannot be any confusion.
Currently my background layer is simply transparent, and for my own visualization the next layer has an image of a shiny CD surface that I found on the internet - I turn that layer on when I want to see a fake idea of how the shiny silver will look with the rest of my design.  A link to a old copy of my Illustrator file is in post #19 of this thread, and here is a JPG of how it looks with the fake shiny background image (the content on my label has progressed since those files was made, but the color ideas are roughly the same).
So, are you telling us the Screen Printer (replicator) is not providing
some sort of Proof to show you what the your art files will look like
when printed?
I don't know - I didn't ask whether the prepress work is being done at their small facility here in town or in Taiwan.  I'm smarter now, so next time I talk to them I'll ask.
It's actually pretty difficult to show what a printed silver disc will look like on white paper.
I agree - that's why I put that image in my Illustrator file so that I could simulate the effect a little.  I know that proofs on paper will look different, and that even my simulation is not real, but I'm doing my best to imagine the end result, and I'm not all that picky as look as it looks nice and the text is readable.  One challenge is that my logo (whose real colors are totally different - see my PR page for both the logo and the jacket design with which I'm trying to coordinate) modified for use on the label has both white and purple in it, so the semi-transparent shade needs to be sufficiently distinguishable from both such that the logo shows up nicely.
Also, the song titles are currently white, but I'm flexible - they could be purple, silver (i.e. completely transparent), or cream - whatever would show up well.  I chose white because I noticed on other examples in my music collection that when text is a solid version of one of the colors involved in a halftone background (which in this case would apply to both purple and transparent silver), the dots touching the edges of the text made it look sloppy and a little hard to read.  For the logo it's unavoidable because I need multiple colors, but the song title text is only one color, so I thought white would be safest.
By the way, I also plan to make the DVD logo and other things I add on the left transparent, not white as you see the DVD logo now.  I'm waiting until the last minute to combine the paths with the purple area to make that happen, because after I do that, moving those items around or changing their size would be difficult or next to impossible.
I have found presenting clients with separations only confuses them.
I wouldn't be surprised.  But in my case I am the client and the artist, so I would fully understand separations.
We also offer samples of what we have printed in the past
and do offer check discs to see what the art will look like printed on
the disc.
My replicator offers a full-service check disk if I want to pay for it, including not just the label but the data as well (the first disk pressed from the glass master), but it costs $60, adds significantly to the turnaround time (it is made in Taiwan, of course), and the guy said that most clients don't opt for it unless they have a really big run (mine is only 1000 copies, so I'm in the very small category).
Thanks to both of you for all the great conversation!