Date Published: 2008-10-01
|
Underbasing for digital printsDane Clement explains how to create a digital underbase for a direct-to-garment printer… |
Why create your own underbase?
First things first: do you need an underbase channel for the digital images you are printing? That will depend on your printer and the colour of the shirts you are printing.Not every shirt colour needs an underbase. Whites and lights do not need an underbase. Examples of light colours are typically pastels such as yellow, khaki, light blue or light grey. If it's a lighter colour, you can use the highlight white to finish it off, (see 'Highlight white channel'). Medium to dark colours typically need an underbase.
Similarly, only direct-to-garment printers with the capability to print white ink, (those printers that are marketed 'for printing onto darks'), will require images to have an underbase channel. Not all printers have this capability – for example, the Brother GT-541 is currently a 'light garments only' digital printer. If the printer does print white ink, it has to have RIP software so that it knows what to do with those extra channels. As mentioned above, some RIPs do a better job of underbasing than others. Most will auto-generate underbases, but in my opinion the underbases produced in this manner do not produce very good printed results. If you are looking to purchase a new direct-to-garment printer, bear in mind that the printer is likely to be supplied with bundled RIP software. When comparing printer specs, be sure to ask whether the printer allows you to create your own underbase channels or whether you are locked into those that the RIP generates automatically. Most RIPs will let you bypass the automatically generated channels and create your own. But you should check to make sure. The rationale behind auto-underbasing is that many printers do not want to be bothered with creating an underbase channel for themselves – it's just another thing to worry about. However, I believe that investing the extra effort and short amount of additional time required to create your own underbases will pay big dividends, allowing you to produce a higher quality job in only a minute or two. Personally, I want to bypass the RIP or use the RIP only after I have created my channels. I don't want it creating my channels for me.
Red alert!
Having decided to take control over the underbases for your digital prints you will soon learn from experience where to boost the underbase and how to handle certain colours. For example, let's say you want to print a 'fire engine red' on a dark shirt: for this, you would need to put down a large volume of white under the red on your base channel - somewhere around 80% - 100%. However, if you are printing a darker shade of red, your underbase may need to be only 40% - 50%. I create my underbases in exactly the same way 90 percent of the time; however, with certain colours, such as reds, I'll invariably go in and make some essential adjustments. One of the most important things to do when producing an underbase for digital printing is to have your art on a transparent layer in your image manipulation program, (Photoshop in my case). Once your art is on a transparent layer you can switch the background layer from black to white. You must have your art on a black and white background for this technique to work properly. This is the case whether you use the RIP software to create the underbase, or you do it manually.
Figure 1
Figure 2. Drag the curves so that they resemble those shown here. This will give an excellent underbase for 90 percent of your digital prints. Essential Info
Look at the artwork to determine whether there are any areas that may need a denser white underneath: the underbase should be darker under the lighter colours of the image. For example, as stated previously, if you're printing a bright red on a dark shirt, you'll need a lot of white under the red areas to produce a bright final print.You can learn a lot about separations and colour from the Info palette in Photoshop. If you're not familiar with this palette make it a point to start using it. (Get used to having the Info palette open at all times – Window>Info, or press F8.) By turning on and off the preview 'eye' icon of your channels you can see how much white you have in certain areas. Select the underbase channel and move your cursor around the image, watching the Info palette to see how the density of white changes between different areas of the image. Try mousing over any red areas of the image: the Info palette may show a 40% - 50% coverage. If so, you might want to increase the coverage in those areas up to 80% - 100%. That is a hard-and-fast rule: you should boost the density of the underbase under any red areas that you want to look nice and bright on the final print. If you don't, your 'bright red' will look like a brick or maroon red when printed on a dark shirt.
Figure 3. One for all
It is most efficient to create an underbase channel that can be used on any colour of dark shirt. Some printers that are concerned with minimising the amount of ink might say, "Well if I'm going to print a red shirt, I want the red of the shirt to be in the red areas of the design." That's an option, but it means creating a specific underbase for that colour. The inefficiency of this approach becomes apparent when you want to print that same job on five different colour shirts: you'll risk driving yourself nuts creating individual underbases for each one! One of the most common mistakes when creating underbases is inadequate coverage. This makes the images look dull and lifeless. You can fix this, but you have to test print. All direct-to-garment digital printers that are capable of printing white inks require dark shirts to undergo some sort of pre-treatment before printing. This pre-treatment is usually in the form of a spray, which might be applied by hand, or automatically by the machine, depending on the make and model of printer. The pre-treatment lays down the fibres to produce a smooth surface to print onto. The pre-treatment also helps the ink to adhere to the garment. The result is vibrant looking prints and minimal fibrillation.Highlight white channel
Figure 4. with the artwork layer selected go to Select>Color Range. In the Color Range dialog box, click on an area of the image that is bright white. Adjust the 'fuzzy' slider – I usually stop at around 30 on the slider – then click OK. While the white area is selected, create a new channel in your channels palette. Fill the selected area with Black. This data will print as white on the printer. When you have created your underbase, print it on a shirt. Then, go back in and tweak the colours a little bit if necessary. Welcome to the learning curve! Once you get a feel for it, it's not that tough and you'll find you really can create an effective underbase channel for any image in just a minute or two.
|
Dane Clement is renowned for his expertise in
computer graphics and colour separations. He
works as an application specialist and is the
founder of Great Dane Graphics – a supplier
of high quality vector artwork for garment
decoration.
Web: www.greatdanegraphics.com |
|
IMAGES is published by: CN Publishing, 9a, Kings Road, Flitwick, Bedfordshire, MK45 1ED, England. Tel: 01525 718890/717655 IMAGES website designed and hosted by Cyberscreen Internet Services |
Dane Clement is renowned for his expertise in
computer graphics and colour separations. He
works as an application specialist and is the
founder of Great Dane Graphics – a supplier
of high quality vector artwork for garment
decoration.
Web: 
