Let’s take scenario A): We wash an used fleece jacked that we just wore for a run (mechanical forces) together with a pair of jeans and a shirt in the GUPPYFREIND washing bag. The fabrics inside the bag will lose many ‘bigger’ microfibers. In this scenario, the bag will capture almost all the microfibers. Its efficiency is 100% (or close).

In scenario B), we’ll put a new, cheaper fleece jacket inside the GUPPYFRIEND washing bag. Only a few fibers break, because it is new and washed alone in the bag. Tiny nanoparticles are on the surface of the fabric, for example from the manufacturing process. These will not be held back by the bag. The overall microfiber loss is approx. 1.4 g of residues. The bag does not capture dissolved substances, nanoparticles or dust. Only two-thirds of the released fibers will be held back by the bag in this scenario. The efficiency of the bag is somewhere close to 70%.

We have done uncountable wash tests with various test institutes, universities and industrial partners in Europe and the USA. We will do more testing with the Fraunhofer Institute and the German Textile Research Institute to understand more about the parameters affecting microfiber shedding. Based on these results, we have come up with ideas for reengineering textiles and insights on how to gradually improve the GUPPYFRIEND, come up other filter solutions, and alternatives to existing, harmful textiles and production methods.

We are also working on a film to make the testing process and results transparent and public.

Conclusion: What we can claim is that textiles washed inside the GUPPYFRIEND lose fewer fibers compared to those washed without the bag, and that the washing bag reliably filters out the microfibers that break during washing.