Prepping image for screen printing?

[baresoulsurfer]

I've been struggling with an issue for a few weeks now, and I would appreciate any help I can get. I prepared a logo for a group at a local university (as a favor for a friend) using a a few layers with a quickmask technique. I'm running Photoshop 7.0 in Windows XP, and right now the file is sitting at 10"x10" at 300dpi. Here is a .jpg copy of the image: http://img.photobucket.com/albums/v317/baresoulsurfer/SemperFiLayerscopy.jpg

The problem I'm come up against is this: they want to get the logo printed on t-shirts, and my attempts to get this file to the printer aren't working. I'm not sure what to do to prep this image for screen printing, but the tips I'm getting from the printer aren't working. I don't think that the printer is very experienced, and I'm not sure that he really knows what he's talking about with the explanations. I realize that the problem with this particular graphic is the gradients in the image, but I'm not sure how to change them into halftone dots, which is what I've gathered I need to do. Feel free to correct me if I'm wrong!

I've tried creating duotones, I've tried creating spot colors in the channels palette, I've tried pretty much everything I can find in online tutorials and help forums, but this isn't working.

If anyone can explain to me what to do in photoshop to make this work for the screen printer, I would really appreciate it. Thank you very much!

 

[MindBender]

The thing with screen printing is that it requires, basically, a custom halftone style pattern. You could probably get this printing separations on a postscript enabled printer (think laser printers not inkjet). It could be possible to do this by "faking" it, eg, creating the halftone patterns within the image itself so that you aren't sending gradients, but instead halftones.

What methods has the service bureau suggested to you so far? My usual first stop is to talk to the person doing the printing since they will know what equipment they're using... although it's possible to get someone inexperienced and run into problems. Are they doing these by hand or using an automated screen builder?

Good luck.

Welcome to PSG.

 

[baresoulsurfer]

That's exactly the problem.. the printer is inexperienced, and I'm running into problems. The only advice that he's given me is that there are no true gradients in screen printing. He said that he needed duotones and spot colors, so I created duotones and new spot channels and sent them, but he didn't know what the channels palette was, so I'm not sure he was asking for what he really wanted. He said that everything must be solid shapes and objects, and I understand this, but from what I've found, the conversion from gradients to halftone dots happens with the post script printer. He hasn't answered any of my inquiries as to his equipment. I guess I need a way to "fake" the halftone dots, so I can convert the gradients before I ever send it to him, but I don't know how to do this effectively.

 

[ronmatt]

To begin, your art isn't prepared correctly. A) use cmyk colorspace, not rgb. B) The black should consist of black only, no under-color. Color trapping for screen printing can be a nightmare. C) you have a black square field with the logo centered in it. If you want just the logo to print, remove the square field.
Once the above is done, your 'screen printer' should be able to make his own separations for print. If, for some reason, he can't, maybe he should consider chucking his business and getting a taco stand. Simply save your image as a PDF. Your printer should have print settings for separations in Acrobat which he'll use to print to film, (negative or positive,depending on how he's set up ) He must have a Postscript printer and/or 'In-Rip' separation capability. All the info he needs is in the print set-up dialog within Acrobat Pro ( not Reader ). In there he determines the PPI and LPI and film/plate requirements. I believe screen printing frequency ranges between 45 - 65 LPI and the resolution should be a minimum of 300PPI. If you are to provide film, you'll need positives, RREU. Your service bureau should know this.

 

[MindBender]

To begin... etc. etc.

He's not talking about "screen printing"... he's talking about "silk screening". Which is a far more black art than offset press. How the art is prepped really depends on the printer themselves... most of whom are pretty non-technology oriented.

As for prepping the images... again... depends on the printer unfortunately. My original advice pretty much stands from my experience. Basically you have to dumb down your artwork into solid globs of paint... there are no tones in screening.

 

[baresoulsurfer]

To begin, your art isn't prepared correctly. A) use cmyk colorspace, not rgb. B) The black should consist of black only, no under-color. Color trapping for screen printing can be a nightmare. C) you have a black square field with the logo centered in it. If you want just the logo to print, remove the square field.
Once the above is done, your 'screen printer' should be able to make his own separations for print. If, for some reason, he can't, maybe he should consider chucking his business and getting a taco stand. Simply save your image as a PDF. Your printer should have print settings for separations in Acrobat which he'll use to print to film, (negative or positive,depending on how he's set up ) He must have a Postscript printer and/or 'In-Rip' separation capability. All the info he needs is in the print set-up dialog within Acrobat Pro ( not Reader ). In there he determines the PPI and LPI and film/plate requirements. I believe screen printing frequency ranges between 45 - 65 LPI and the resolution should be a minimum of 300PPI. If you are to provide film, you'll need positives, RREU. Your service bureau should know this.

That part I know.. it was only in RGB so I could save it as a jpeg to post on photobucket as an example. The black was just a layer that I put under the image to show it in jpeg, but it wasn't sent with the file to the printer. I sent it 10"x10" 300 ppi CMYK with one layer of white and one layer of PANTONE 1797C as a PSD. If the choice to change printers was mine, it would be done. Thank you for explaining this process further, I'll try it as PDF and see if this gets me anywhere.

 

[graphikill]

i would change that to a vector style logo for screen printing..

all you need to do is supply each colour as a black image so use the select colour tool to pic each colour out then put that on a new canvas and save it

 

[MindBender]

i would change that to a vector style logo for screen printing..

In this case, working in vector as an output source would probably be counter-productive. Since the printer is most likely inexperienced and this is an often non-technological printing method, simply prepping the image as a raster with the halftoning already built into the image will usually give you the most bulletproof workflow.