Also, if you are not buying spools at a fabric store or walmart, etc. (with those, you get all purpose, or 50 wt).... then when looking at the thread, remember the weights (wt) is backwards in a way.
90 wt is very fine..used in bobbins for embroidery machines.
60 wt is fine...also used in bobbins for embroidery & sewing machines. For longarm quilter's Bottom Line (a Superior thread) is used sometimes for very small stippling, and other intricate designs...to avoid thread buildup).
50 wt is what is usually used for all purpose sewing. Coats n Clarks all purpose thread is a 50 wt, 3 ply thread.
most serger cones are 50 wt, but are a 2 ply thread, so may look thinner, but they are very strong, and work well for piecing quilts and general sewing.
40 wt cotton or poly thread is usually reserved for quilting or embroidery (top thread for the machine..and in embroidery, usually it's rayon or poly).
35 wt is usually used in quilting when you want the stitching to really stand out.
30 wt...same as above.
Now, Tex 27...that's probably equal to 50 wt.
If you go to
http://www.superiorthreads.com you can find a lot of great information on threads. Which needle to use with which thread...tension issues, etc.
Whatever you do, don't use quilting thread on the spools (Coats n clark, etc.) on your machine...as I mentioned earlier, it has a coating on it & will gunk up the machine over time.
Marge