Screen print a 3 color image

[Roderick Treece]

First, Thanks for all the great tips batching !!!

I have a fine art color photograph that I want to screen print on glass. My plan was to

separate the three channels RGB RED GREEN BLUE in photoshop.

Take each separation and turn them into half tones (PS)

Make film negs of each

burn screens

Print each color on glass with trasparent inks( 3 layers of glass total)

Put them back together in front of each other to create the image.

I do know how to do the separtions and the halftones. What I don't is...

How do I figuire out what color to make each layer. When you lok at the total RGB image it is in color but when you look at the individual channels they are black and white.
Is there somewhere to see what the PMS print color for each would be?

Hope that makes sense

Thanks
Roderick

[erik winkler]

First of all I do recommend to use cmyk instead of rgb.
And therefore you will need 4 screens instead of only three, but then you are able to use true inks, since rgb is light.
Combine rgb screens and it will be blackish-brown instead of the white you have intended when using rgb together.

This is how i would do it:
1. Open photo in Photoshop.
2. Go to channels and deselect magenta, yellow and black.
3. Look at the result and conlcude that this is indeed the cyan layer.
4. Delete the deselected layers by sliding them to the trash can underneath the chanels pallet.
5. Go to image:mode: grayscale
6. save a tiff file and print this file as your cyan layer/screen.
7. re-open the photo and do it subsequently for the three other color layers/screens.

Erik

[Mark Summers]

I think Erik is right on the cmyk as you can buy inks for cmyk
but I'm not sure how one would accommodate the rgb as you
would have to guess at the colors and what might you get,
as I would guess.
Nice approach Erik has on the color seps.
Tell us how you come out with this project Roderick and post
your picture.

Mark

[Mike Jackson]

Roderick,
Let me throw out a few comments.

You are going to need transparent process inks for this process and you are going to need some very accurate screen registrations. You will need to rotate the dot pattern of each screen to negate the moire pattern. You'd need to save each film positive at a fairly coarse dot pattern for a silk screen. CMYK is probably the better choice over RBG. And remember, most printing is done on white stock, so you may need to back up the entire image with a layer of white to illuminate the underlying transparent colors.

If the sign project is small enough, and if you know someone with an Edge printer, just have them run out all four "colors" in black on clear film positive. Gerber will do all the work for you. You can set the resolution to larger dots if necessary for a screen. Most screen printers will want the positives to be emulsion side up and you need to remember to make the screens in reverse. I'd suggest adding three or four registration targets to the file before printing the positives, too. You can scrape them off afterwards.

Good luck,
Mike Jackson

[Roderick Treece]

Thanks again everyone !

This is going to be a fine art project so for the first test I'm going to do it around 8.5 x 11.

One thing that stumped me was CMYK. I know what it stands for but I didn't know that you just buy those colors ready made. I was thinking I would have to mix them to match.

I am not going to worry right now about exact registration as I will be printing the image right up to the edge of my glass.
Moire pattern is not an issue at this point because I'm interested in seeing what effects are going to happen when the 3 panels are placed in front of one another with a separation of an inch between.
A lite back ground will be nesessary but I am going to wait till the end to see what it will need.

My question now is what dot resolution is good for a halftone screen ?

Thank again

Tahnks again

[Mike Jackson]

Roderick,
I don't have the specific answer in front of me but it has to do with the screen mesh and the distance you need it to look good. There are probably charts on the Internet to help you, but others here could probably help. David Butler used to screen on T-Shirts and would probably know the two variables he used.

Good luck,
M. Jackson

[Travis Stanley]

There is a website advancedartist.com that has a software plugin for corel draw that does color seperations and halftones, It will even provide registation for your prints. Also Steve Yates Graphics offers a very resonable plugin and has a free trial offer. With tutorials.

[Anthony Bennett]

Roderick, there is a guy in the states called Scott Fresener, he runs the US Screen printing Insitute
www.screenprinters.net
Anyway, he wrote a book called How to print t-shirts for fun and for profit, i don't know where to buy it or if it is still for sale but it explains everything you are talking about.
Ok the books about cotton not glass but the theory is the same.
Maybe it might be worth looking over his site or getting a copy of the book.

The registration should not be a problem, heck they screen print photo quality stuff on t-shirts.

Also, I thought coreldraw had a built in ability to print seperate screens in its print set up page so I cant see what the plug in would do, I would like to know though.

Anyway, don't know if this will help but thought I would add my 2cents worth

[Travis Stanley]

I think the concept behind the plug-in is to save time with the separations i.e. halftones, colorseps, and registrations. He has some Nice tutorials on his website @ www.steveyatesgraphics.com
And I think there's a free 90 day trial. Something worth checking out

[Anthony Bennett]

Thanks for that Travis, an interesting site

[Patrick Mackle]

I took a color file to Ford Graphics in Glendale, Calif.
I had them inkjet print my color file onto a self adhesive acetate material that can then be applied to glass with a mild soapy water solution.
The acetate already has a nice transparent white layer that backs up the colors printed on it. The glass and acetate prints were all backlit.
Due to the glue layer, these images will probably outlast printed screen paint adhesion by a long time.
Pat