Colour is both an art and science when it comes to digital product decoration. The art comes into play when you’re designing what to put on your product. The science comes in during the print and press process. Andrea Evans, Sawgrass’ international marketing manager, reports.
Understanding how colour works in a digital print environment is essential to success in sublimation. Though colour science can be complex, here are some basic concepts that will help you achieve great colour output and repeat business.
What is colour management?
The colours you see on your screen will never match the colours in your prints exactly. This is because the colours on screens are generated by combinations of three colours: red, green and blue (RGB). Conversely, digital printers use anywhere from four to eight ink colours to reproduce the image from your screen. CMYK (cyan, magenta, yellow and black) is the standard for four-colour digital printing.
Computer monitors emit colour as RGB light. Although all colours of the visible spectrum can be produced by merging red, green and blue light, monitors can display only a limited gamut (range of colour) of the visible spectrum.
Printed products absorb or reflect specific wavelengths of light, unlike a screen that emits light. Cyan, magenta and yellow pigments or dyes serve as filters, subtracting varying degrees of red, green and blue from white light to produce a selective gamut of spectral colours.
Challenges specific to sublimation
With dye sublimation, there is another element of the colour control process that must be addressed. When a dye sublimation transfer sheet is heated and pressed onto a substrate, the ink turns into a gas that bonds with the polymers of the substrate. During this ‘gassing’ process certain colours will shift, so the finished product will not look like the original image on the screen.
You may also notice that colours of the ink printed on your transfer paper are very different from the final image that is created when heat and pressure are applied. This is because of the chemical characteristics of the dye sublimation process, and another reason why colour correction is needed.
With sublimation, these issues need to be addressed for each individual printer and ink combination. In extreme circumstances, colour correction may be needed for every combination of printer/ ink/ substrate and transfer paper. However, extensive testing has shown that in most cases, good-quality transfer paper does not affect the final colour. This is why we recommend that you only use high-quality paper.
Colour management basics
Now that you know why colour management is necessary for sublimation printing, let’s look at a few ways this is accomplished.
- ICC profiles: An ICC (International Colour Consortium) profile is a set of data that ensures that when a specific colour is selected on the computer screen, the designated colour is consistently and correctly delivered on the substrate. Think of it as a colour-matching programme, since the screen colour rarely produces the same colour output. A profile creates a link between specific screen colours and specific output colours. It doesn’t change the colour, rather it ensures the correct output for a given input.
- Custom print drivers: Custom print drivers are programmes that have colour correction built into the printer control system. The advantage of these programs is that colour correction is performed at the print driver stage, and they are generally easier and less technical to use than an ICC profile. Look for sublimation printers whose manufacturers produce a specific custom print driver.
Easy tricks of the trade
As a digital product decorator, there are a few things that you want to make sure you do to ensure your colours will sublimate as you expect:
- Apply the correct colour management tools: Each of the options discussed above have specific ways to apply the software to your prints. Get trained on how to apply them correctly and make sure you do so with every print.
- Always design in RGB: Most design software has a set colour mode for the design space of the file you create. They are usually RGB and CMYK. When working with sublimation, you need to activate a specific RGB profile to produce accurate colours.
- Print and press colour charts: Whether you are using an ICC profile or a custom print driver, we suggest you create a colour chart by printing out and sublimating an entire palette of colours to a pure white substrate.
- Consistency is key: Any change in any of the variables in the create, print and press process will impact your final output. These include substrates, sublimation paper selection, pressing time, temperature and pressure, as well as colour management techniques.
There is much more to be said about colour management, but these basic concepts should help you gain a better understanding of what’s going on when you create, print and press – and how to get the colours you want.