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Piecing and Sewing

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  • Cotton Thread
  • Tips and Tricks

What to look for in a high-quality piecing thread

An excellently pieced seam requires skill in addition to the collective use of good components. One of the major components of a good seam is the thread that is used to create the seam. Most quilters prefer cotton thread when it comes to piecing (the term piecing is used more than sewing because the sewist is piecing together their quilt blocks) because cotton fibers have a high heat tolerance and is therefore iron-safe on high heat. Generally speaking, cotton fibers are also softer and more pliable than most other fibers.

When looking for a quality piecing thread, you should find a thread with the following traits:

Thread twist. The twist of the thread should be consistently smooth and tight. If you hold the thread up to the light to inspect it and If you see bumps in the thread or inconsistent twisting throughout the length of the thread, it is not considered to be high quality. These bumps, or slubs, will get caught in the tension discs, contact points, and in the needle which will result in lint buildup and a weakened thread as it is snagged. These slubs will also add unwanted bulk to the pieced portions, resulting in not-so-flat seams.

Fuzz factor. If you hold a cotton thread up to the light and see no fuzz at all, don't use it in your machine. Either the thread is mislabeled or it is a glazed cotton thread. Glazed threads are for hand quilting, not machine piecing or quilting because the glaze rubs off in the tension discs and other areas of the machine and can gum up the machine. If you see a lot of fuzz and uneven amounts of fuzz along the strand, it is not a quality thread. If you see a very small amount of fuzz and the thread is consistently smooth, it's a good cotton thread.


MasterPiece cotton piecing thread
MasterPiece is the best cotton piecing thread
MasterPiece thread in a needle
Cotton threads will naturally have a little bit of fuzz

Thread thickness. Cotton threads are almost always either a 2-ply or 3-ply thread. A high quality 2-ply thread can be stronger than a lower quality 3-ply thread due to the fibers and the processing, while a 3-ply thread can have a tighter twist resulting in a smoother, thinner thread than a 2-ply thread. A thin, smooth thread will make the best seam because it lies flat in the fabric. Therefore, assuming the quality is the same, a 50 wt. cotton thread will make a better seam than a heavier 40 wt. cotton thread. When pressed, the finer thread will make a better seam and the points will match up better.

Strength. A non-glazed, fine cotton thread will not win any strength contests by itself. However, because the average stitch length for piecing is 12 stitches per inch, the strength is in the quantity of stitches. You don't need a thread with a record-setting tensile strength. A high-quality 50 wt. cotton is the perfect piecing thread for the job. If you find that your top thread is breaking, check the needle size (we recommend using a size #80/12) and reduce the top tension to 4.0.

Piecing with matching colors. I recently saw a beautiful quilt that had what looked like pencil marks next to all the seams. I wondered why the quilter didn't erase them. Upon closer examination, what I was seeing was a gray thread showing through a yellow fabric. Had the quilter pieced with a matching yellow thread in the top and bobbin, this distraction would have not been noticeable. Although many think that white, cream, and gray threads are the only necessary colors for piecing, matching the piecing thread color to the fabric really does make a big difference. This is why MasterPiece cotton thread is available in so many different colors.

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