Fabric bags are a great promotional item. A large print area and re-usability are just two great features. When it comes to getting your logo onto the bag, there are several choices. But not everyone is a print expert, so let us explain what they all mean in our Fabric Bag Branding Guide.
There are three main print methods: Spot colour screen print, CMYK screen print and CMYK heat transfer. Each of these methods has different strengths and weaknesses which make them ideal for one job and not necessarily the best choice for the next.
Spot Colour Screen Print
Screen printing is the most common type of printing for fabric bags. Its quick and cheap and has a great finish. We can print up to 7 colours as standard but it is possible to add more if needed. Speciality inks like metallic finishes and neon colours can also be used with this process.
How it works
Screen printing is very simple at its most basic. A fine silk mesh is stretched across a frame to make a screen. Thick ink is placed on top of the screen which is then positioned above the bag. A squeegee blade pushes the screen down onto the bag and slides across the screen. This pushes the ink through and it ends up on the bag.
In order to make images, you need to be able to block the ink from going through certain areas and allow it in others. This is controlled by a special photosensitive film. The artwork is split into separations, one for each colour. Each separation is then printed onto a film which is then treated. This treatment allows ink to pass through the printed parts of the film but not the rest. The film is then applied to the silk screens, one for each colour.
Next you need a machine that can hold the screens in the right place so that they can be swapped around and still line up in exactly the same place above the bag. A separate ink is mixed for each colour and placed onto the right screen. One squeegee per colour later and you have a finished, multi-coloured print!
- Flat colour designs without shading
- Accurate colour matching
- Logos and text
Not so good at:
- Photographic images
- blended colours (graduated tone)
CMYK Screen Print
The screen printing technique can, (with a little persuasion!) produce photographic images. There is a bit more work processing the artwork to get the best print results, but once that is done, it is just as fast as normal screen printing. As always with CMYK printing, it is important to remember that white is not included! Sometimes that can be important, as it may be necessary to add an extra screen, especially on dark coloured bags.
How it works
With CMYK screen prints, only the four primary colours of ink are used. They are cyan, magenta, yellow and black. By mixing these colours in different amounts it is possible to produce almost any colour. In theory, when all the colours are mixed it should make a very dark colour, but it is not quite a true black. By adding black as a separate colour, a greater range of colours can be printed.
You might remember that shading is not so easy with screen printing, so we need a trick to be able to mix different amounts of each ink to make all the colours needed. That’s where half-toning comes in!
Half-toning uses a dot pattern to fool the eye into thinking that you have printed a lighter shade of your ink colour. The image is converted 4 separations (one each for cyan, magenta, yellow and black) and each is converted to a dot pattern. Where the darkest colour is needed, the dots are very large and overlap each other, which lets all the ink through. Where it is lightest, the dots are small and have gaps between them.
Although the dots in each separation are exactly the same colour, the gaps between them allow the background show through, which gives the impression of a lighter shade. When all four colours are overlaid on top of each other, your eye sees it as a single full colour image.
On a material like cotton which has an uneven, rough surface, a coarse dot pattern needs to be used. This means that the halftone pattern is visible when you get close up and it can blur or break up the edges of small details in the artwork.
- Large photographic images
- Gradient Fills
- Drop Shadows and other effects
Not so good at:
- Small text and fine details
- Flat colours
- Critical colour matching
CMYK Heat Transfer
If you need fine detail and photographic images then heat transfers can be a great option. For larger runs, heat transfers can be a more time consuming process. But the great looking results mean it can be well worth investing in.
How it works
Heat transfers split the printing job in two. A large digital inkjet printer (just like the one you have at home!) prints your design to a special heat transfer material. This is made of two layers, a carrier and a heat activated glue.
The transfer is then cut to shape and a large, hot iron presses the paper onto the bag. The glue activates and the carrier paper is removed leaving the image stuck to the bag.
Because the ink is printed on an inkjet printer to paper, much more detail can be produced than when printing direct to the rougher cotton. The glue that keeps the image on the bag makes a stiffer, glossy patch on the surface. This can make the bag less flexible in printed areas and will show up as a shinier surface compared to the cotton fabric.
- Detailed images for close up viewing
- Small text and details that need to stay sharp
- Smaller runs of full colour artwork
Not so good at:
- Fast turnaround jobs
- Large print areas
- Solid colours
For more information on the fabric bags that these print techniques are used on, please see our complete fabric bag range.
Our unbranded Spice Products site is perfect for showing this printing guide to your clients. All the information they need to know, but delivered under plain cover, with no trail back to Kan.