A thread about threads

I'm getting into hat making and I want to use to use the best possible materials and tools available. I have an old Singer 112-4 sewing machine. Would you recommend polyester or cotton thread for sewing in sweat bands, hat bands etc? I've read that it isn't wise to use polyester thread on natural fabrics because over time it can wear down the fabric and rip since it is so strong. But don't know if that applies to rabbit/beaver/nutria felt or not. I'm wondering if anybody has any recommendations or if it even matters. Just trying to cover all my bases. Thanks!

I have used different threads for each. A stronger/heavier thread like Coats and Clark upholstery for sweat bands and often I use Gutermann polyester or S-lon Superlon beading thread for ribbon hatbands. I've found that the S-lon works well in both applications as S-lon is thinner in thickness and is quite strong. I've had no degradation of the felt or grosgrain ribbon using these materials. I've looked back at hats I did over 15 years ago and can't see any issues having developed.

In all cases, I try to stay away from cotton threads altogether as they have lower tensile strength and the thread has a tendency to fray, or weaken, with age as it sits on the spool between uses. I do use small quantities as I'm only doing a few hats each month. The thread can end up sitting a spool for long periods of time before I go through an entire spool (literally years). Also, I do all my stitching by hand, not machine and that is a big reason for me wanting a stronger thread to begin with. I've had too many instances where a cotton thread has broken in the middle of a job and I've had to pull stitches and start over. I'm sure you can imagine how frustrating and time consuming that might be.