So I found a used thread injector at a garage sale for $10 that looks like some kid's "my first sewing machine" which is perfect for me to learn on. I have some $1.50 ripstop from Walmart, and some camo ripstop on the way (thanks to sclittlefield and the group buy). I've got some really cool ideas for a top quilt and an Under quilt. I have 900 down on the way from another group buy. I've read just about everything I can get my hands on and I'm super excited to get started.
My plan was to make a stuff sack first out of the Walmart ripstop to get the machine settings right. Then maybe a gear hammock to practice with longer seams.
I have almost everything ready to go, but I don't have any thread. I went to the local sewing store looking for guterman 100% polyester, since that is what was recommended in my readings. When talking to the lady in the store, after hearing what I was using it for, she had recommended some heavy duty upholstery thread made of nylon. She knows a lot more about this than I do, so it made me pause. I paused so much that I didn't buy either one and came home to read some more. I couldn't find much more than "use guterman, it works for me".
I know that there are some issues with rot and cotton thread is out of the question, but why not nylon thread? The fabric is nylon and would have some stretch presumably, so wouldn't it make sense to use nylon thread on nylon fabric? Anyway, I couldn't explain to the lady or myself why I needed 100% polyester guterman thread, so I recognized that I needed more information. Please help me clear this knowledge deficiency.