It's amazing how much thread is in one garment. At first, I could only estimate how much thread I needed to purchase to sew Danu and I always underpurchased. The majority of our stitches use more than one piece of thread at a time, making them very durable and giving our garments a long life, but using a lot of thread.
It's rather common for even natural fiber clothing to be sewn with plastic thread. Seeking out organic, natural fiber thread is hard to do these days. But for responsible, circular fashion, it's important to choose garments sewn with natural fibers.
Another upside of organic cotton thread is that it will overdye nicely. Plastic-based thread will remain the color of the plastic instead of accepting natural dye.
We purchase our thread from Julie Moore's company, Fiberactive Organics. We use her Sewpure™ GOTS certified, organic cotton thread in the color wheat. It is the finest organic thread we have ever found. Beyond that, Julie Moore also loves Sally Fox's cotton plant we use to make all Danu clothing so much that she grows it in her garden for her own hand spinning.