Everything we do leaves some kind of footprint on the ecological landscape. From the school run to growing food, humans are constantly doing things that generate pollution or CO2 (or both) and use up natural resources. But what is important is how responsibly we perform these actions, how the materials and techniques are used to impact the environment over the long term, and how efficient the processes are.

Screen printing happens to be a pretty sustainable way of printing onto fabrics. We have written an in-depth account of the whole process here, so it's definitely worth a read if you want to know a lot more about how images go from your desktop to your t-shirt. In a nutshell, though, each individual colour gets its own screen, which is essentially a stencil that's embedded into a very fine gauze. The gaps in the stencil are where the image appears, which happens when inks are forced through the tiny gaps in the gauze using a rubber blade. What's great is that the same gauze can be used over and over again. 

The stencil is formed chemically, in a process rather like printing a photograph, and once the print run has been completed, the negative image can simply be washed away, leaving a blank gauze for the next run. Alternatively, if the screen is going to be used repeatedly, it can be stored and re-used. Either way, you are limiting the impact of the production of gauzes. 

Screen printing is perfect for making a thick, hard-wearing layer of ink that will last for years and multiple washes. When you factor in the quality of the clothing itself, you can create printed garments that you'll get lots of wear out of. Most other types of printing don't give that kind of longevity and will fade after several washes, leading to more landfill.

There are two main families of screen printing ink in use: water-based and plastic based. By some measures, the water-based inks are, on paper, greener than plastic-based ones. The main eco credentials come from its manufacturer and disposal, as the chemicals used are kinder than plastic and are more biodegradable.

However, that's only part of the story, and it's one we have weighted up over the years. Plastic-based screen printing inks are simply better quality than water-based ones, and they are much easier to work with, giving more predictable results and superior opacity. Water-based inks work well with light-coloured fabrics, as they soak into it more, meaning the base colour will show through. Plastic inks are entirely opaque, so they can be printed on any colour of fabric, including black, and will remain vibrant and detailed. Also, water-based inks require a lot more labour (i.e. energy) to prepare the garments for printing, whereas with plastic inks, it's a case of putting the garment in place and pressing the button on the machine. Finally, because they last longer, the ecological impact of creating new garments is less than that of water-based inks, which can fade over time.

In summary, there is much to be said about water-based inks for screen printing. They have a unique, almost retro look to them when they are printed, and that is exactly what some customers are looking for.

The environmental impacts of manufacture and disposal also have to be taken into account. Plastic-based inks might not have the eco credentials in themselves, but they shift the balance back in terms of how much wear you get out of them and how many garments are wasted in the printing itself because of the more complicated and error-prone process required by water-based inks.

If there were water-based inks that addressed all the benefits of plastic-based ones, it would be a no-brainer. Still, it's hard to see how any material could reproduce the opacity, flexibility and longevity. Rubber-based inks exist, which rival plastic in terms of opacity and flexibility, but they are still relatively rare and come at a premium price - and although the product is more biodegradable, rubber plantations themselves are water-intensive, so it's not so clear cut. 

The most eco-friendly thing you can do is, of course, to not wear clothes at all, or at least to forgo any kind of decoration on the ones you wear. But since people want to wear printed clothing, and businesses want to have branded uniforms, printing is here to stay. Printing adds just a small amount of energy and material to the whole impact of growing cotton and treating, spinning, weaving, tailoring and delivering it. As long as it is done responsibly, it doesn't have to have a huge ecological impact.