Thread Talk

Following is the second part in a series of articles on threads, their differences and their uses. This is used with permission by Bob Purcell of www.superiorthreads.com

A generation ago, there were very few thread choices.  It was almost is if one type of thread was used  for every project, whether that was piecing, quilting, clothing construction, upholstery, and so on.  Times have changed and much better quality products are available today.  Thread has become more specialized to enhance and improve our sewing projects.  
There are differences between quilting, embroidery, bobbin, applique, serger, upholstery, and, construction threads.

Bobbin Thread
Some teach that we should always use the same thread in the top and in the bobbin.  I think the reason they recommend this is to keep things simple and also thinking there will be fewer tension problems.  However, it is perfectly fine to use a different thread in the bobbin and, in most cases, it is actually preferred. Here's why:
Quilting
a.  A fine bobbin thread reduces the bulk in the seam.
b.  You can wind more fine wt. thread on the bobbin than a medium wt. thread.
c.  Tension can be easily adjusted to accommodate different threads.
d.  A finer thread blends well.
e.  A finer thread is usually less expensive.
Embroidering
a.  A fine bobbin thread leaves a softer, more pliable embroidered design.
b.  You can wind more fine thread on the bobbin than a medium wt. thread.
c.  A finer thread is usually less expensive.

Whether quilting or embroidering, it is recommended to match the color of the bobbin thread to the top thread just in case a little bobbin thread occasionally shows. The most common bobbin threads are 50 wt. and 60 wt. threads.
Recommended bobbin threads
MasterPiece  #50 extra-long staple Egyptian-grown cotton.  Very little lint.  Iron safe.  75 colors.  600 yd. spools and 2,500 yd. cones are 3-ply.  MasterPiece prewound bobbins are 2-ply.
So Fine #50  #50 smooth, lint-free polyester. Polyester is stronger and less expensive than cotton.  Recommended to set iron to low or medium heat. 134 colors.
Bottom Line  60 wt. smooth, lint-free polyester.  Recommended to set iron to low or medium heat.  55 colors.
MonoPoly   Invisible polyester monofilament thread available in Clear and Smoke colors.  Commonly used as a bobbin thread for quilting and thread painting when using many different colors on top.  Recommended to set iron to low or medium heat.  If you like monofilament thread, make sure you use polyester monofilament and not nylon because nylon tends to go brittle, discolor, and has a lower heat tolerance.  Some brands of monofilament invisible threads are labeled "polyamide" which is the chemical name for nylon. MonoPoly invisible thread is 100% polyester and the preferred type.