Margareta Fuchs and Everson Scheurich of DTG Merch discuss colour accuracy in DTG printing and share some pointers on how to achieve it in your shop
Colour accuracy is one of the most overlooked areas in the direct-to-garment (DTG) printing industry, but it can make the difference between a stunning print and a mediocre one. There are now almost no limitations design-wise with DTG: it’s possible to use hundreds of colours at once, make photorealistic images and use gradients. But all this freedom comes with a cost: it is difficult to predict accurately how the colours of the final print will look.
Everson Scheurich and Margareta Fuchs of DTG Merch
Colour differences between screen and print
Colour spaces are the main culprit why your colours on the screen often do not match the printed ones. Your monitor operates in RGB, while your printer uses CMYK. The CMYK colour range (or gamut, the range of reproducible colours) is smaller than RGB. Typically, when converting from RGB to your printer’s colour profile, the colours shift to fit into the smaller gamut and become less vibrant – muted, even. This conversion is usually handled by RIP (raster image processing) software, which translates the design into a printable file.
The problem is that, unlike printing on paper, there is no standardised colour management system available for DTG printing. It is very hard, therefore, to obtain a good on-screen preview of the final print. An additional problem is the gamut of your specific printer. It may differ from the standard CMYK colour space used within designs, especially when you use a printer with additional colours, such as six-colour systems.
How to set up your design files
Since DTG uses white ink, all the white parts of the design will be printed, including the background. For this reason, as a printer, you need to receive or create a file type that can handle transparencies and which has a transparent background. This will allow the colour of the substrate (shirt) to show through in the background areas. Even though RIP software accepts various file formats, there is no ‘one best’ file type for DTG printing. They all come with advantages and disadvantages.
PNG This is an extremely popular format because it’s easy to handle and it allows for transparencies, but it does not support CMYK. Within a PNG file, all colours available in RGB can be used – technically even neon. As a consequence, large colour shifts can occur once printed. On the other hand, information about the real gamut of the printers aren’t readily available. Designing in RGB avoids unnecessarily leaving out colours that would be printable (remember, the CMYK gamut might not match your printer’s gamut).
PSD and TIFF These file formats can handle transparencies as well as CMYK. They need more skilful handling and it’s of utmost importance that the files are set up and exported correctly, eg any transparencies and colour profiles must be embedded.
JPEG These files are not recommended as they are unable to preserve transparency. You can use them when printing with CMYK on light garments, but not for printing onto dark garments with a white ink printer.
Last but not least, the resolution of your design can affect the colours as well. The RIP software converts your design to your printer’s resolution (usually between 300-1,200dpi). If the resolution of your design is too low, it may cause imperfections. A good rule of thumb is to set up the design with a resolution of 300dpi at your actual printing size.
Some causes of colour inconsistency
It is extremely difficult to predict the colours in a final print since so many factors influence the outcome in DTG printing. These factors affect not only the printed colours, but also the whiteness of the underbase. This means your white point changes, which can drastically alter the colours. Some of the factors that can influence the outcome are:
The garment itself There are colour variations between different types of garments, materials and fabric dyes. And there may also be variations between T-shirts of the same model, due to the natural differences of the fibres or normal production inconsistencies. A colour printed on one T-shirt might not match the one printed on the next.
Processes Differences in handling can influence the colour outcome. For instance, slight inconsistencies in the pre-treatment application can affect the whiteness of the underbase and therefore influence the final colours of the print.
Environmental conditions Differences in temperature and humidity can change the properties of the ink.
Printer profiles Often, printer profiles are for general use, eg ‘white T-shirt’, and not optimised for a specific type of garment.
Differences between printers and inks The gamuts vary greatly, and it’s almost impossible to compare them.
Designs The used colours are outside of the printable gamut or the colour profiles are not embedded correctly.
How to achieve more accurate colours
First, try to get your processes as stable as possible. Second, test different file formats, colour profiles and garments to get a feeling for how they perform. Afterwards, establish some standards and clearly communicate them to your customers. Instead of trying to proof colours on the screen, you can reverse engineer it. Print patches with different RGB values (you can download them for free on our blog) to see how the colours are reproduced in an actual print. Add the new values to your design. The colours on the screen may look incorrect, but the printed result is going to be closer to your intended outcome.