Computer Graphics with Photoshop

Author

Silk Screen Seps

Stephen

2006-09-12, 10:17 pm

OK I'm the first to admit I know nothing about screen printing prepress.
I've just been given a job, where I'm to convert a .jpg bitmap into
colour separations for silk-screen printing. I'm planning on using
PhotoshopCS for this.

Any suggestions, URLs to read in how to do this? I'm familiar with doing
litho/offset prepress, but don't know the specs or what's required for
screen printing. I guess I basically need a Step X Step guide.

I've Googled, but most of the hits that I got, were for suppliers of silk
screen printing equipment. :(

2006-09-12, 10:17 pm

Stephen wrote:

> Any suggestions, URLs to read in how to do this?

GOOGLE photoshop silk screen for 900,000 hits.
Right at the top

http://www.ehow.com/how_10251_compu...erated-art.html

better.... disregard the Mac orientation because it makes no difference

http://finearts.uvic.ca/sim/help_do...n_printMAC.html

I leave it to the reader to go further

Larsonist84@gmail.com

2006-09-12, 10:17 pm

I do silk screening Stephen, as you know you just need to have 1 image
file for every color used. each color is its own layer.

Those links mentioned in the previous reply should help you, if not
shoot me an email and i'll be glad to offer help.

Stephen wrote:
> OK I'm the first to admit I know nothing about screen printing prepress.
> I've just been given a job, where I'm to convert a .jpg bitmap into
> colour separations for silk-screen printing. I'm planning on using
> PhotoshopCS for this.
>
> Any suggestions, URLs to read in how to do this? I'm familiar with doing
> litho/offset prepress, but don't know the specs or what's required for
> screen printing. I guess I basically need a Step X Step guide.
>
> I've Googled, but most of the hits that I got, were for suppliers of silk
> screen printing equipment. :(

Stephen

2006-09-12, 10:17 pm

On Tue, 12 Sep 2006 11:35:35 -0500, j in
comp.graphics.apps.photoshop wrote:

>Stephen wrote:

[color=darkred]
>GOOGLE photoshop silk screen for 900,000 hits.
>Right at the top

Yeah I got similar prior.

>http://www.ehow.com/how_10251_compu...erated-art.html

>better.... disregard the Mac orientation because it makes no difference

>http://finearts.uvic.ca/sim/help_do...n_printMAC.html

>I leave it to the reader to go further

J:

Thanks, I know how to print/output -- What I need to know is the tech specs
and step x step, on creating the separations from a bitmap for a screen
printer workflow. Sorry, I guess my question wasn't as clear as it could
have been. I'm dealing with a client that don't know themselves -- and
they basically want to outsource the prepress/design, to me. So, at this
point I'm simply consulting with some good will.

FWIU they print to positive where white doesn't print, and black does.
Is this correct ?

If it helps any, here is the URL to what the client wants me to work
with. It's not pretty; <http://sda.awardspace.com/>

Any additional suggestions, welcome.

2006-09-12, 10:17 pm

Stephen wrote:

> Thanks, I know how to print/output -- What I need to know is the tech
> specs and step x step, on creating the separations from a bitmap for
> a screen printer workflow.

I am at home now so I cannot point to the specific menu, but there is the
option to export each color channel as an image with one-click. You might
surf around Help with things like Export, Channel... dunno, Sir.

seversky

2006-09-13, 3:16 pm

If you are doing 4-color process then I would suggest converting your JPEG to CMYK and do as the above post mentions: export each channel as a grayscale image.

If you are using some odd number of colors, the fastest way I know to get the job done is to convert your image to indexed color. You won't get a nice halftone pattern, but if done correctly it will still look professional.

1. First convert the image to the approximate DPI of the silk screen (somewhere between 50 and 90 DPI, depending on the quality of your screen and your camera).

2. Go to Image -> Mode -> Indexed Color..., set the number of colors to use, select Custom for the pallete and choose the colors of the inks you will be using. Choose the type of dithering you want (diffusion always worked the best for our screens). Click OK.

3. Now convert back to RGB so you can create layers

4. Use the Magic Wand tool with "Contiguous" turned off to select one of the colors.

5. Create a new layer, and fill the selected area with black. Create layers for each color in this way.

6. Each layer is now a color separation and you can export them individually or do whatever you need to do with them.

Mohamed Al-Dabbagh

2006-09-24, 6:15 pm

Hi!

First of all, and because you don't have a good idea about silk screen
printing (as you say), refer to this excellent introduction:

http://en.wikipedia.org/wiki/Silk_screen

There are some rules to be followed for feasible and excellent results:

1- Use no more than 3 colors in 100% tints..

2- If you use no more than 3 colors, use vector software such as Adobe
Illustrator. Use spot colors only, such that you can see design in
color final form, and be able to separate without the need of process
colors CMYK.

3- Many people would use the ordinary laser printer. However, you may
expect better results if you hired a service bureau to have
separations. The reason behind that is the dense (Black) you can get on
lithographic film compared to using laser ink. Dense black will lead to
a very satisfactory stenciling.

4- In silkscreen process, it's a great idea to consider trapping the
edges. The overlapping of adjacent colors may cause gaps if you don't
take trapping into consideration.

5- In case of deciding use more than 4 colors (for the necessity of
creating many colors) the color separation using process inks should be
separated such that line frequency should never exceed (53 LPI). The
reason is to create larger dots that can be easily stenciled.

Mohamed Al-Dabbagh
Senior Graphic Designer

Stephen wrote:
> OK I'm the first to admit I know nothing about screen printing prepress.
> I've just been given a job, where I'm to convert a .jpg bitmap into
> colour separations for silk-screen printing. I'm planning on using
> PhotoshopCS for this.
>
> Any suggestions, URLs to read in how to do this? I'm familiar with doing
> litho/offset prepress, but don't know the specs or what's required for
> screen printing. I guess I basically need a Step X Step guide.
>
> I've Googled, but most of the hits that I got, were for suppliers of silk
> screen printing equipment. :(

Stephen

2006-09-24, 6:15 pm

On Tue, 12 Sep 2006 17:11:50 -0500, j in comp.graphics.apps.photoshop wrote:

>Stephen wrote:

[color=darkred]
>I am at home now so I cannot point to the specific menu, but there is the
>option to export each color channel as an image with one-click. You might
>surf around Help with things like Export, Channel... dunno, Sir.

j, thanks for the response.

I guess I'm not explaining myself well, (not at all unusual). I know how to use
Photoshop/Illustrator, heck I've used both since the early days.

I know how to create separations for Offset printing, manually, as I
understand offset litho.

What I don't know, is the technical requirements of doing what I need to
do for screen-printing CEPS/Prepress, and perhaps some advice on using
the 'LiveTrace' function in Illustrator (I realize that this is the
wrong list for the latter, so will save that ?, for the appropriate list).

I really don't want to have to manually trace this image, unless I
absolutely have to. So I guess I"m asking for advice from separators
that have experience in the Screen printing prepress genre.

Stephen

2006-09-24, 6:15 pm

On 13 Sep 2006 05:37:17 -0700, Mohamed Al-Dabbagh in
comp.graphics.apps.photoshop wrote:

>Hi!

>First of all, and because you don't have a good idea about silk screen
>printing (as you say), refer to this excellent introduction:

>http://en.wikipedia.org/wiki/Silk_screen

>There are some rules to be followed for feasible and excellent results:

[...]

Mohamed:

Great Stuff ! Thank-you so much. I can't believe that I didn't even
consider Wikipedia for this, as I tend to use it for other queries.

The technical information <ie> LPI is quite helpful. I can't believe
that my client doesn't even know such basic information themselves.

Again thanks for taking the time to answer my question. May the force be
with you. ;)