As a retailer of organic cotton t-shirts (www.bgoecoshop.com), we are constantly seeking the perfect printing method that makes eco as well as dollar sense.
Well, in actual fact, it appears that there really is no perfect printing system. So says printing expert Eric Wilmanns of Brown and Wilmanns Environmental LLC who were formerly Patagonia environmental staff. Asked by Econscious organic apparel to survey the existing ink technologies on the market, here’s what they say:
As much as we strive to reduce the impacts of our printing, the fact is that there is no environmentally perfect printing system. But for any given printing scenario there are better and best choices. In general these choices strive for fewer toxic ink and process related compounds. Fewer solvents, and less processing in general. There are tradeoffs – get rid of one bad chemical and you may need more water for cleanup – or energy for curing. Remove PVC form the plastisol formulation and ink cost might go up. It is all an environmental balancing act. To make matters even more complicated design, application, durability and price all end up in the balancing act!
(See the whole report here.)
In apparel printing, screen printing method is the most commonly used and economical method to choose. And there are basically three types of screen printing options: Solvent-based plastisol ink, water-based ink and discharge printing.
Typically, organic cotton apparels are printed using water-based ink. It has no or lower VOCs (volatile organic compounds), no PVC (polyvinyl chloride) and fewer chemicals/solvents involved in cleanup. However, one of the downside is that water-based ink can consume more energy to heat and evaporate water. It can also still have toxic ingredients and additives.
One solution to this would be using eco inks like Permaset Aqua 100% solvent free inks and Matsui 301 Eco Series Water-based Inks. Also, textile manufacturers should also seek Oeko-Tex Standard 100 certification, which limits the use of certain chemicals in textile dyes.
In comparison, solvent-based plastisol printing inks based on PVC polymer are widely used in apparel screen printing process, due to its quick curing time. However the process involves Dioxins (one of the most toxic chemicals known, many of which are carcinogenic), phthalates and heavy metals that can be toxic to wildlife if released irresponsibly.
The better solution to this would be choosing plastisol inks that are free of Pthalate, heavy metals and PVC.
Water-based discharge printing (for use on dark-coloured garments) involves a bleaching process that uses a reactive chemical called Zinc formaldehyde sulfoxylate (ZFS) which can cause health problems. Formaldehyde and sulfur dioxide gases developed in the process can also be detrimental of health.
Printing aside, regarding garment dyeing, you can refer to our previous blog on natural dyes such as plant extracts.