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Separations by hand
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Imaging screen printing screens with Print Lamps
CMYK samples
Shin Kohanga art samples
Using Ink Blocking
  
       
   
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Colour separation software
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Colour Separating Designs with a Computer

Colour separating a design is taking an original piece of artwork and breaking it down into a number of separate designs, from which screens/masters are made. The separations are printed over each other, in layers, to create the original design.
 
There are a number of ways to achieve colour separations:
Using artwork pens to trace the design and draw on an overlay sheet [details of this process - click here . .]
Taking a number of photocopies and blocking the unwanted portions [details of this process - click here . .]
Computer scanned imaging & graphic colour separation

By Computer: Scanning & colour separating

The original design we started withComputers are the best method of colour separating as they enable you to move, re-size and manipulate your design quickly and accurately.

Here’s a simple example and guide to using a computer for colour separation [also known as layers]. On the right is the original design we want to work with [it’s actual size is 140mm x 90mm], however we wish to separate the colours, change the message and make other changes to personalise the image.

Important: Not all computer design programs allow layering/ colour separations. Check the program you have first - most design programs have tutorials and instructions on separating colours/ creating layers [in PhotoShop press F1 and see Using Layers]. If this function is not listed in the help/ contents list then the function is not available with the program you have.

In this example Adobe PhotoShop 5.0 is used with a PC computer, Scanner and Laser Printer.

 

Step 1 - Scanning the design
You need to get a copy of your design into the computer to work from. Place your original design into the scanner and scan at 1200dpi [actual size] in true colour. If your computer can’t handle 1200dpi lower the setting or use 256 colours.
Step 2 - Size your design
After scanning you may have an excess border, or unwanted background, around the design area - trim this by re-sizing your canvas or using the Marquee Tool to copy and paste your design to a new file - save the new file & work with this one - delete the old file].
A note for later: When you have finished all your separations you may wish to re-size the dpi from 600dpi to 300dpi to save on disk space.
Hint: Turn off the layers you are not working on so you don’t get confused as to what you are removing [or you have to start again]
Hint: Name each layer according to printing order or colour to be printed - this helps when removing colours from layers or stacking the viewing order
 
Step 3 - Creating your layers/ colour separations
There are two methods you can use to create your layers from the one design:
 
Method 1 - Make multiple copies of the entire design and remove the unwanted areas - Just like the blocking method when separating by hand.
How It's Done: Use the Marquee Tool [M] to highlight your entire design - Copy [Ctrl+C] and Paste [Ctrl+V] into the same layer. You will notice that this does not override your design but creates a new layer [can’t see it - then view the Layers window] and is labeled Layer 1. Repeat this process for each layer/ separation you need to create, then select a layer and using the Pencil Tool [set colour to White] remove the area around the part of the design you wish to keep - effectively rubbing out the parts you do not want.

Hint: Using the 2nd method you can easily check if all parts of the design have been assigned to a new layers and separated, by creating an extra layer and using this as a ‘Cut & Paste original’. Instead of Copying [Ctrl+C] use the Cut [Ctrl+X] command when tracing colours and placing them into a new layer. After all areas have been placed on new layers - this layer should be blank.

Method 2 - Highlight areas on your original and then paste them back into the same file - making a new layer. This is similar to the tracing method when separating by hand, however the computer can ‘trace’ many areas at once.

How It's Done: Use the Magic Wand Tool [W] to select areas of your design for each layer. Once you have selected the design area/s Copy [Ctrl+C] and Paste [Ctrl+V] back into the design. This creates a new layer for each selection. Repeat this process for each layer/ colour separation you need to create.

Both methods require some patience and a steady hand - the number of final colours/ layers often determine which method is best.

 
Step 4 - Registering your layers/ separations
This is the step where it all comes together, as if you don’t register the design correctly here, your prints will not match up!

How It's Done: Make sure your original background design [all colours] is on the bottom, with the layer you wish to register viewable. Highlight the layer you wish to register and use the Move Tool [V] to reposition your layer over the corresponding area on the original design below. Once a layer is registered, turn the layer visibility off so it can’t be seen. Select another layer and repeat the registration process for layers. [For fine detail areas Zoom in - 500% or 600%].

Step 5 - Compiling your design & printing
When separating colours for screen printing it’s difficult to combine layers and print two colours at once [two colours on the one squeegee], however when printing with PRINT GOCCO, you should combine as many layers and colours as possible - provided they can be separated by Ink Blocking on the Print Master and will print in order!

How It's Done: With design separated and each layer registered over the original design - turn off all the layers. Start from the top and select a layer [so only it is visible] then print the picture. Only the viewable layer will print - label it immediately - now repeat the process for each layer [making it the only viewable layer].

For registration use the Crop Marks/ Registration Marks option in your printer settings . If this is not available or you didn’t put registration marks on the original, you must register each print by hand - at least you know each screen will be accurate due to your hard work!

Summary

Our original design was separated into 9 different colours/ layers, plus the original background layer. After mixing & matching, the layers were combined to form a series of 3 final layers/ separations from our original design - the 3 designs as shown below.
Note: 1 layer was left out of the final prints

Print #1  Print 1 - A combination of 3 layers [Body Colour, Moon & House Lights]

Print #2  Print 2 - Just one layer in the end as this takes up most of the design area. [Night Sky]

Print #3  Print 3 - 4 layers combined to create the final print [Houses, Silver Stars, Gold Message & Angel Outline]

Our final printed design

Click to enlarge

Click to view large version

 

How may layers/ separations do you need?
PRINT GOCCO - different colours can be combined on single layers [using ink blocking] reducing the overall number.
Screen Printing - a separate screen for each colour is required as colours can not be combined on the same separation/ layer.
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