Sew Fine! thread from Superior.
What do you do when you find out that something you thought was true, really isn’t? If you are me, you write a blog post for all the world to see :-).
If you have ever been in my class, you know that I use cotton thread with cotton fabric. That’s not going to change because cotton thread has many characteristics that I like. However, one of the main reasons I have not recommended using polyester thread is that I believed that it might degrade faster than cotton over time. This was based on old information that may have true back in the day but is no longer relevant.
I have been doing quite a bit of research on thread and I ran across this academic study that looked at the biodegradability of polyester vs. cotton. You can read the whole paper, or skim it, but here’s the very short story:
The researchers took cotton and polyester jersey fabrics and subjected them to the same treatment. All fabrics were laundered 30 times with various washing products to simulate garments at the end of their useful lives prior to testing. They were then buried and composted for 3 months.
“The polyester fabric showed a slight initial degradation, but the fabric was still intact after testing under both laboratory conditions and the compost environment. In soil and compost testing, which included multiple organisms and enzymes, the cotton fabric with softener had an accelerated degradation rate, while the cotton fabric with resin showed a relatively slow degradation rate.
All cotton samples were more significantly degraded in the compost environment than under the laboratory conditions and confirmed to be ‘compostable’.”
I’ve been wrong about this aspect of polyester thread. I still don’t love it for the kind of sewing that I do. Polyester thread doesn’t tolerate high heat from an iron, it is slippery, and it is shinier than cotton. But there is nothing suspect about the fiber itself. If you have a place where it makes sense to use polyester, go for it. Who knows… it’s possible I might find myself using it in some future project.
Lastly, it is true that polyester is basically a plastic. Many of us, me included, are trying to cut back on the amount of plastic we use. However, until we manage to cut out much bigger sources of plastic in our lives, I think it’s safe not to obsess about the plastic in polyester thread.