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compartista
Inspiring
November 20, 2021
Question

HELP Screen Print Gradients, and halftones

  • November 20, 2021
  • 2 replies
  • 5663 views

So, I've had a few jobs in screen printing, one I got fired from because I didn't know what I was doing.  I am now working for another screen printer, and I have a few questions. I was even willing to pay someone to help me for a few hours, but she flaked, anyway. 

 

My problem is, I know the concept of screen printing, i just don't understand how to print the film.  We do have RIP software (wasatch) and I am hoping someone can enlighten me with these questions, i know that if i don't figure this out I will get fired again, and I am scared I don't want to loose my job. 

 

Here are the questions.

1) will RIP software print gradients? I've heard on numerous You Tube videos you have to change the gradient to a halftone, so if that's the case is the film that's got the gradient on it, for example a yellow color, will the film print a yellow gradient/ or a yellow halftone if this makes any sense? 

 

2) I made a design (stupid me) that I don't even know how to print and it makes me nervous, I am going to submit that here.  PLease tell me how this will print. Theres a bunch of offset paths, and when i click on it there are millions of lines, and it scares me! LOL. What do I do to make this a better file to use for print? 

When I look at it to print on the screen in the print box, it's all there and it looks good, but my question is 

are those black dots going to print, I didn't even assign a black color to this piece? ugh. like i'm really confused.  I was thinking what's going to print are tiny holes, instead of dots.  The bottom of basketball is a white outline and the shirt is going to print throug, with the gradient on top and with the letters in gradient as well. 

 

Any help is appreciated. 

 

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2 replies

Inspiring
November 20, 2021

Followup.  Question number 2.  That design appears to have been already printed ( see halftone dots in Blues ).  In order to get the White, you need to do either a flash or a flood using White undercolor.  So, the actual inks you use to print the shirt will probably be three: 1. White, 1. Black, 1. Blue.  "Lady Wolves" lettering has a blue gradient inside it.  "Basketball" has another blue gradient.  There are other methods of printing, such as inkjet or thermal transfer which may be easier.

Inspiring
November 21, 2021

Another important consideration is moire pattern in the gradients.  To minimize this, you would assign an angle when creating the 1-bit halftone screen in Photoshop.  There is a way to determine the angle based on the mesh of the silk screen you plan on using for the printing.  It could be 75 degrees, 15 or 0 degrees.  In fact, you may want to do a series of angles, such as 90, 45, 75, 15, 0, etc., print films say around 6" x 6" of each and place them on top of a silk screen and see which combinations produce the least amount of moire.  On top of that, you have the shirt's sewing pattern that affects the screening, too.

compartista
Inspiring
November 21, 2021

ok i will use that information at work tomorrow and see how that works out, thanks for all your advice, very much appreciated. 

Inspiring
November 20, 2021

Let me try to help...

 

"1) will RIP software print gradients? I've heard on numerous You Tube videos you have to change the gradient to a halftone, so if that's the case is the film that's got the gradient on it, for example a yellow color, will the film print a yellow gradient/ or a yellow halftone if this makes any sense?"

 

- Screen printing is really quite complex.  So, yes, the RIP will "generate" a gradient, however, you need a RIP that will print separations as "halftones" and send that to you as film positives ( which are then used to make the actual individual screens for printing on garments}.  There is another way, too.  You could export the artwork as a .tiff file and open it in Photoshop.  More on this in answer number 2;

 

"2) I made a design (stupid me) that I don't even know how to print and it makes me nervous, I am going to submit that here. PLease tell me how this will print. Theres a bunch of offset paths, and when i click on it there are millions of lines, and it scares me! LOL. What do I do to make this a better file to use for print?"

 

- You could export the artwork as a .tiff file and open it in Photoshop.  It gets a little tricky because you should size the artwork before Export out of Illustrator.  Open the .tiff in Photoshop ( if you have it and you should ) > Go to Channels > Split Channels ( you should get 4 CMYK channels: 1. file.cyan; 2. file.magenta; 3. file.yellow; and 4. file.black ) > these should be Grayscale files. In your design, if it prints on dark, you will need a flash White underprint channel, to get this, you will duplicate one of the Channels and Invert it.  Consult with a local source to help you with this because it is pretty complex manipulations and there will be some additional retouching, I'm sure.

 

Getting back to your artwork.  In Photoshop, open the Cyan channel > you should see a grayscale version of the separated cyan colors > go to Image -Mode = Bitmap > Resolution = Input - whatever your original file is, Output - 2540ppi; Method = Halftone > Halftone = Frequency - 35lpi ( for mesh of silk screen ), Angle - 75 degrees ( or whatever is suitable for the mesh of the screen and the channel itself ), Shape - Ellipse.  In these steps, you are bypassing the RIP and doing the halftones yourself, but they still need to be output onto clear film for generationg the silk screen(s).  Since you have chosen a field which you have little to no training, no education that we know of, perhaps you may want to get that before venturing into screen print design and prepress. 

compartista
Inspiring
November 21, 2021

I didn't realize I was in over my head when I started doing screen printing, it is a lot. But, I am determined to get a handle on this. I actually understood everything you said.  Because I've never printed a gradient before, I just don't know what it's going to look like. I didn't even think about photoshop.  It makes sense now. Essentially, as you said it's only 3 colors. 

 

However, If I am printing spot colors, how does CMYK channels help me? What would I do?