When you print a map or a layout on a standard office printer or plotter, the colors you see on the page are typically made up of a mixture of cyan, yellow, magenta, and black dots of ink, in varying proportions. These four ink colors collectively are called CMYK or process colors. When you send your work to a print service provider to be output on a larger offset printing press, typically the same four inks, CMYK, are used. The CMYK model provides a wide array of colors, which are typically sufficient for most uses.
In some cases, you may need an additional, custom ink color. This is an additional channel—physically a different ink used in the printer. These colors are called spot colors. This custom ink may have a different appearance (such as metallic, luminescent, or clear coat) from standard ink, or it may be a very specific color that is difficult to achieve by mixing CMYK. When a special ink is defined, all of the elements in the file that reference that special color are collected together in a single channel in the final export file (usually a PDF file). Everything in this channel will be printed with the special ink. Typically, when spot colors are used, the export file contains the four process colors and a single spot color channel. There are cases where more than one spot color is used, or only spot colors are used, but be aware that using custom spot colors can significantly increase printing costs.
Understand spot colors
A common topographic mapping example for using a spot color is to define a specific brown to be used for contour lines, contour labels, and spot height labels. These are typically symbolized with fine lines and small text, so when their brown color is made up of dots of cyan, magenta, and yellow ink, the slightest amount of misregistration can make them appear fuzzy. To mitigate this, a spot color can be defined so that these features print with a single solid ink.
Since the actual appearance of the spot color is determined by the ink colorant used in the printing press, ArcGIS Pro needs a color definition to mimic the appearance of the spot color on screen or in output devices (such as a desktop printer) that don't support spot colors. So, when you define a spot color, you also define an alternative color that is used to display the color in these conditions. The alternative color is typically a CMYK color that is visually close to the actual spot color. In addition to the alternative color, spot colors are defined by their name. The spot color name is important because it is the link that ensures that all colors defined in this way are compiled together into a single channel in the export file. For this reason, do not rename a spot color once it has been defined, because you will lose this connection.
Spot colors are stored in styles. You cannot convert an existing color into a spot color. Do not confuse the name of the color style item with the actual spot color name. When a color is applied to a symbol from a style, the operation is by value, meaning that no reference is maintained back to the style. The entire color definition is copied into the symbol. You can rename the color style item if you must, but preserve consistency in the spot color name.
Tint and transparency in spot colors
In addition to the main properties of a spot color, name and alternative color, spot colors can also have a tint and a transparency.
When a spot color is applied to a symbol, you may want only a percentage of the ink used to get a lighter version of the color than when the ink is laid down in a solid coat on the page. Just like in process color, a screen is used to get an arrangement of small dots of the spot color ink to achieve this tint. Specify the relative amount of ink (the darkness) by setting a tint value percent on the spot color. Tint can be specified when the spot color is defined as a style item, and it can be modified when you apply the spot color to a symbol.
Transparency can also be specified in a spot color as a percentage value. Please note that the handling of transparency in spot colors can vary depending on the printing press implementation. Some press equipment may not work properly if both transparency and overprinting are applied to an item. Talk to your print service provider about whether transparency is supported by their equipment before deciding to use transparency with a spot color. In most cases, it is recommended to not apply transparency to a spot color.
Define a spot color in a style
Spot colors are different from other colors in ArcGIS Pro in that you cannot convert an existing color to a spot color, and you cannot convert a spot color to an existing color. You must define spot colors directly into a style. You can then apply them from the color picker, which shows all available colors from the current project styles.
Follow these steps to define a spot color in a style. You can create spot colors in any editable project style or in your Favorites style.
- Make a catalog view active. If a catalog view is not open in your project, on the View tab, in the Windows group, click Catalog View .
- In the Contents pane, click Styles and click an editable project style .
- Under Manage, on the Styles tab, in the Create group, click the New Item drop-down arrow and click Color .
A new color, named Color, is added to the style with a default RGB black definition.
- Highlight the new color, and at the bottom of the Details panel, click the Description tab. On the Description tab, specify a name for the color style item, and update the Category, Tags, and Key properties if necessary.
If necessary, under the Manage tab, on the Styles tab, in the Options group, click Details Panel to open it.
- At the bottom of the Details panel, click the Properties tab. From the Color Model menu, click Spot.
- Specify a name for Spot name. Note that this is independent from the name of the color style item. Ideally, this name is not changed after the color is created, because it links all items referencing this color together in output.
- Click Change to define the Alternative Color color definition used to display the spot color on screen and on any output device that does not support spot colors. Typically, this is a CMYK color that is visually similar to the intended spot color ink that will be used on the printing press.
- Optionally specify a Tint percentage. Do this if you expect to use the spot color at a specific percentage often, and you want the convenience of having a style item defined that way already. Otherwise, leave Tint at 100% and change the tint iteratively as you apply the spot color.
- It is recommended to leave Transparency at 0% (fully opaque) unless you have specific instructions from your print service provider.
- Click Apply. The color is saved into the style. Spot color chips, shown in the style and in the color picker, are differentiated by a small dot on the lower corner for easy identification.
Use a spot color
Follow these steps to apply a spot color to a symbol, including symbols on text and layout elements, or anywhere else you choose a color.
- From the color picker, choose a spot color. Spot colors are identified in the color picker gallery with small dots in the corner of the color chip.
- Optionally open the color picker again and click Color Properties to open the Spot Color Editor dialog box.
- On the Spot Color Editor dialog box, adjust the Tint property to use a lighter version of the spot color. It is recommended that you do not change Transparency unless you have specific instructions from your print service provider.