White ink is a great way to enhance your print. It brings playful innovation to your designs and also allows you to print on materials you wouldn't usually be able to, like metallic, plastic or dark stocks.
White ink can be used on its own or as an undercoat alongside a four colour process. Here are the basics of designing and setting up a file for white ink printing.
Setting Up a 'White' Channel
Before you can start designing, you'll need to create a white channel to show us which sections of the design should be printed with white ink.
- Select any spot colour and re-name the swatch 'White' (making sure the 'W' is capitalised). Anything that is selected with the 'White' swatch will be printed in white.
Try using something noticeable, such as pink. This will help avoid confusion with other, more common colours in the document. (See fig 1.1)
- Be sure that overprint is NOT selected with objects assigned to the white channel. (See fig 1.2)
- To print white text, assign your text as the 'White' swatch. The same concept applies for strokes, drop shadows, fills etc.
- The areas of 'White' will appear as the spot colour you originally selected. Although this can be confusing, try to visualise that it will eventually be printed as white. (See fig 1.3)
For the white to print as fully opaque, the channel must be set to 100% opacity with no tints, effects or overprints.
Different effects can be created by experimenting with these settings but for solid white, stick to 100% opacity.
Make sure the 'Colour Type' is set to 'Spot'
The 'Attributes' window for 'White' objects
Left: How your file will look on screen
Right: How it would print… (on black paper)
Overprinting onto 'White'
Any colours you want printed on top of white ink must be set to 'Overprint'. (See fig 2.1)
If 'Overprint' is not selected then the overlaying object will, by default, knock out the white ink underneath. (See fig 2.2)
Applying an Overprint:
- InDesign: Window » Attributes » tick 'Overprint Fill/Overprint Stroke' box.
- Illustrator: Window » Attributes » tick 'Overprint Fill/Overprint Stroke' box.
- Quark: Window » Trap Information » Background » Move from Default to Overprint.
It's worth noting the difference between 'Overprint Fill' and 'Overprint Stroke'.
The blue type has been set to 'Overprint Fill'. (See fig 2.2)
The blue type has been set to 'Overprint Fill'.(See fig 2.2)
Make sure 'Overprint Fill' is ticked
'Overprint Stroke' will need to be applied to any object or type with a stroke that you'd like printed over an area of white.
Applying a small allowance around an overprinted object or type will ensure any small alignment issues are compensated for. Usually a 0.1pt stroke will be sufficient. (See fig 2.3)
To check if you've set overprints correctly, you can use the 'Output Preview' feature in Acrobat Pro:
Acrobat Pro: Tools » Print Production » Output Preview.
You can also use the 'Separations Preview' window in Illustrator and InDesign:
- Illustrator: Window » Separations Preview.
- InDesign: Window » Output » Separations Preview.
- Quark: Export your PDF and view in Acrobat Pro. Then follow the 'Acrobat Pro' instructions above.
If you turn off all colours apart from 'White' in 'Output Preview' you will see the areas to be printed white displayed as black – useful for quick viewing.
Once in 'Separations Preview' you can check the ink levels applied to a page by hovering the cursor over the content. (See fig 2.4)
If you're printing CMYK over an area of white, the 'White' channel must display an ink level of 100% (See fig 2.5).
If you turn the opacity to 99% or below, gradually, the colour and/or texture of the paper stock will start to blend in with your design. You can create some interesting and innovative results if you use this technique well.
With 'Overprint Fill' turned on…
With 'Overprint Fill' turned off… (resulting in the four colour knocking out the 'White')
Turning off the CMYK is a quick way to view areas of 'White' in your document.
How the 'White' channel displays on screen with CMYK turned off.
Creating Undercoats of 'White'
You can also use the Overprint technique to print images onto more complicated designs, rather than just lines or text.
To do this, you'll need to duplicate what you intend to print and convert it into one block or silhouette of 'White'. This will sit behind the design as an undercoat.
This is straightforward for square or circular images, but more complicated shapes can be harder to replicate.
There are two easy ways to do this:
- Copy the original object and 'Unite' the elements with the 'Pathfinder' tool (Illustrator & InDesign) to make it a singular object.
- Manually trace around the object with the 'Pen Tool' (Illustrator, InDesign & Quark) to make your silhouette.
There are many other ways to achieve this result, all are acceptable as long as the final silhouette is accurate to the original shape and set up with the 'White' swatch.
You should also consider an allowance of about 0.1pt. The easiest way to do this is to offset -0.1pt from the size of the undercoat. This can be done by the 'Offset Path' option found in Illustrator.
Alternatively, you can expand the object on top by +0.1pt to create a safety margin (see fig 3.3). If you have an object with a lot of detail, we suggest raising the allowance to 0.25 or 0.5pt. (See fig 3.4).
For text, you can simply duplicate the text box, set it with the 'White' swatch and place it behind your original text. Again, subtracting a stroke of 0.1pt (don't forget to tick 'Overprint Stroke'). (See fig 3.5).
Photographs and images
Photographs or images that you want printed over an area of white will need to be set to 'Multiply'. This is a similar setting to overprint and stops the image knocking out the white ink beneath.
How to apply 'Multiply':
- Illustrator: Window » Transparency » Select 'Multiply' from the dropdown menu.
- InDesign: Window » Effects » Select 'Multiply' from the dropdown menu.
Providing that you have 'Overprint Fill' ticked for the picture attributes, you should be able to see the 'White' channel through the image.
This usually results in the two images merging and looking odd, similar to fig 4.1, but this is normal and will print perfectly.
How your file will look on screen…
How it would print… (on black paper)
Stacking and Layer Order
The stacking order is also important when setting up white ink properly. All overprinted elements must be stacked ON TOP of 'White' elements. (See fig 5.1)
How to change the stacking order:
- Illustrator: Object » Arrange » Bring to Front.
- InDesign: Object » Arrange » Bring to Front.
- Quark: Item » Bring to Front.
'Output Preview' doesn't allow you to check for stacking order, so you'll need to go back to your editable Illustrator, InDesign or Quark document and manually check it (see fig 5.1). Layers with 'White' elements will need to be at the bottom (see fig 5.2).
Final White Ink Checklist
Before you go to print, run through the checklist below to make sure that your file is correctly set up for white ink.
If you are viewing your PDF in Acrobat Pro, you can look at fig 6.1 through the 'Output Preview' to see how a finalised piece of artwork should be set up (Tools » Print Production » Output Preview).
- Have you set the white channel as a spot colour and re-named it 'White' (with capital W)?
- Have you set the 'White' channel to 100% opacity with no effects, tints or overprint attributes applied (unless other effects are desired)?
- If you want any objects or text printed on top of white areas, have you set them to 'Overprint Fill' and/or 'Overprint Stroke'?
- Have you set any images/photographs that you intend to print on top of areas of white to 'Multiply'?
- Are all overprinted items on-top of the stacking order?
- Have you checked any areas intended to overprint onto 'White' display, both the CMYK ink values as well as the ink value for the 'White' channel?
Use of White Ink on Metallic Stocks
Deselecting 'Overprint Fill' (See fig 2.2) on an object or block of type will knock out all ink levels underneath and won't give you the large white undercoating you want.
This in turn would knock out the CMYK values and the 'White' channel right down to the paper, leaving the metallic material showing through.
By setting the previously mentioned object or type swatch to (0%/0%/0%/0%) or [Paper] will mean a 100% opaque knock out occurs leaving nothing but the paper showing through (a good alternative to foil blocking)!