I was just recently introduced to signature ,100% cotton Signature cone thread. I also had a problem with finding large spools of different colors & 100% cotton. I have a reg sewing machine that is not set up for cones. I was told to place the cone behind my machine, run it under the handle(for tension) of my machine then thread as usual. There is an adapter you can buy that sits behind your machine & this works great.
Hope this helps.
Peggy