Matching Threads to Sewing Projects

In the beginning, before the dawn of synthetics, fabrics were simple, all-natural, and easy to select. And so was thread: you chose cotton unless you were tailoring wool and could afford silk thread. In fact, there weren’t any other choices. Sewers got beautiful stitches and seams without puckers.

This charming picture is obviously an oversimplification, but in many ways, it’s more true than false. With the polyester revolution of the 1960s, the sewing machine was thrown a double whammy: 90 % of the fabrics that sewers selected were suddenly no longer all-natural; worse yet, they weren’t even woven. The bulletproof polyester double knits of those little-mourned days created an epidemic of thread breakage and ugly seams, and drove American thread manufacturers into a speedy (and, in retrospect, hasty) response. Cotton thread wasn’t working, so they retooled their factories to produce polyester thread, and cotton thread for the consumer went the way of the dinosaur.

Many sewers get very satisfactory re suits with today’s “all-purpose” polyester and poly-core threads, and if you’re one of them, there’s no need to tamper with your success.

But many other sewers today are not getting good results, and even those who are often have trouble as soon as they venture into projects very different from those that they’re used to. Typically, they blame their stitching difficulties on their machines or on their sewing technique, when in fact puckered, ugly seams result most frequently from using the wrong thread or the wrong needle-and-thread combination. It’s no exaggeration to say that needle and thread are the two most important variables in your sewing, be cause these are what come into direct contact with your fabric. Happily, they’re also the variables that you can most easily change, although your options are much more confusing with thread than with needles.

The simple truth is that sewing machines were designed to sew with cotton thread, and that’s still what they do best. Sewing machine dealers invariably demonstrate their machines with cotton thread, because it provides the best stitch quality. The best thread for any sewing project is the thinnest and most flexible one that can take the stresses the fabric and the garment will subject it to, and cotton is the most flexible of all the fibers made into thread. You can prove this to yourself by pinching a loop of various threads; cotton thread, like cotton fabric, will hold the crease most easily.

Nonetheless, cotton isn’t always the best choice, because of the wide range of possible fabrics today. Other kinds of threads can work perfectly well in the appropriate situation. Before we explore those situations, let’s take a look at what really happens when thread gets ma chine sewn into fabric, and how the various characteristics of thread can cause it to react.

When thread meets machine

As I described at greater length in my previous article, thread whips around the sewing machine at an amazing speed. As it hurtles through the machine, thread is jerked at breakneck speeds through holes that impede or guide it on its trip towards the needle. When it gets there, every inch of thread is pulled back and forth through the eye of the needle about 50 times before it comes to rest in a stitch. Frankly, it’s a miracle that it doesn’t break more often.

Thickness—The eye of the needle is the smallest opening a thread must pass through, and the thread must not exceed the diameter of the hole. Fine needles are the best choice for use on thin, fine fabrics, but puckers will occur if the thread can’t slide easily through the eye. The eye on any needle smaller than a size 70/10 is too small for typical size 50 American thread; choose a thread designated “Fine” or “Extra Fine”. Conversely, if you use a fine thread in a needle larger than an 80/12, you’ll get a lot of thread breakage.

Every time your machine links top and bobbin threads together to form a stitch, a simple knot is created; that’s why the stitch that sewing machines make is called a lockstitch. A seam is thus a series of knots concealed within the holes the needle creates, and in each project that means thousands of knots. With the right thread, the knots don’t cause a problem, but if the thread’s even slightly too thick or too stiff for the fabric, this accumulation of knots can cause puckering. Ready-to-wear often avoids this problem by using a chain-stitch on seams that won’t receive a lot of sideways stress, be cause in a chainstitch the knots are all on the wrong side of the fabric.

Surface texture—Besides it thickness and flexibility, the surface texture of your thread is critical to the way it will react in your machine, and consequently in your sewing. If your thread has prominent slubs, its passage through the needle will cause first fraying and then breaking thread. If it’s rough due to fuzz or coarse dyes, it will catch on the needle, and the stitches will pucker. If its thickness is irregular, it will react erratically within the tension mechanisms.

Once you start examining the threads you buy and use for smoothness and consistency, you’ll soon develop an eye for their surface characteristics. Unfortunately, the quality of a particular manufacturer’s thread isn't always the same from year to year. so it pays to check, even on the brands you’ve had good results with in the past.

Thread in fabric

Once sewn into a seam, there are two other characteristics that will affect your results with thread: strength and elasticity. Obviously, thread must be strong enough to create lasting seams, hut it must not be stronger than the fibers of the fabric. If the thread is considerably stronger than the fabric, it will cause the seams to pull away and fray. It’s much better to risk a broken thread than a ripped or pulled fabric.

Stretchiness can be good or bad de pending on the project. If a stretchy knit or bias fabric will put a strain on the seams, you’ll need thread with enough elasticity not to break during wear. But because sewing machine tension creates drag on the thread as it’s being pulled through the machine, thin, soft fabrics will pucker when the stretched thread relaxes. Crisp or heavy fabrics will neutralize this puckering because they are firmer than the pull of the thread. Any time you’re sewing on a soft, light, non- stretch fabric, try to avoid using a thread that stretches.

If you’re using a stretchy thread, make sure it doesn’t get stretched when you wind bobbins, as it will simply relax and cause puckering once stitched. You can bypass the tension disks for bobbin winding and fold the thread loosely as it winds. In particular, avoid winding bob bins with the thread still threaded through the eye of the needle, as some machine manuals recommend. Some machines can only wind bobbins in this way, which restricts these machines to only the finest quality thread.

When fiber becomes thread

Don’t assume that you should always match the fiber of your thread to the fiber of your fabric. What’s most important are the qualities of your fabric—how it handles. These days, manufacturers can make almost any fiber into almost any fabric. Polyesters, for instance, can be made thick, thin, soft, stiff, gauzy, opaque, and so on. Choose a high-quality thread made from a fiber that will pro vide the needed characteristics for your fabric. I’ve included my recommendations in the following list of possibilities.

Cotton—At its best, cotton thread is smooth, soft, and very flexible. The best varieties are mercerized, which makes them even smoother and more glossy and preshrinks them. Cotton thread has almost no stretch, so it’s inappropriate for most stretchy fabrics, but it’s my first choice for almost any other garments making application. It’s available in weights for any type of fabric. I use lightweight machine-embroidery cotton thread on all silky fabrics, including silks, microfibers, sueded rayons and silks, and polyesters; and regular-weight cotton for tailoring with woolens. Buttonholes, bar tacks, and other satin- stitched effects all work beautifully when done with cotton thread.

Cotton thread dries out in time and be comes brittle, but moisture can be put back in. Washing cotton clothing keeps thread strong once it’s sewn. If you have old cotton thread that breaks frequently, try putting the spools in an open container in the vegetable drawer of your refrigerator. The thread will pick up the surrounding moisture.

Before polyester thread was widely available, sewers working on knits were advised to stretch the fabric slightly as they stitched so their cotton-thread stitches would have some give once the fabric relaxed. This works quite well, but it requires some judgment and skill and a high-quality fabric. It may still be worth the effort if your knit fabric is quite stable and your project has lots of topstitching that would look better with the smooth softness of a top-quality cot ton thread. Narrow zigzags and stretch stitches in cotton sometimes work well on knits, too.

Polyester—The primary reasons for using polyester rather than cotton thread are its strength and its elasticity. I use it in these situations only: in garments made of stretch fabrics: in seams that will receive a lot of stress, like seat seams in pants: whenever I’m sewing real leather or suede; and in projects that will be exposed to the elements, like swim wear and outdoor furniture. Cotton thread will deteriorate when exposed to the chemicals in leather or when left wet for long periods of time.

There are two types of polyester thread available today, spun and long staple. Spun poly thread is made of short pieces of fiber whipped together in a process similar to making cotton candy. The results are much more likely to be slubby and irregular than long staple polys, which are pulled out in long, continuous strands, similar to filament silk, but without the same glossy smoothness. I always choose long staple poly thread, even though it’s more expensive. Buying cheap thread is almost always false economy.

Medium-weight and sturdy fabrics of’ all fibers can often be sewn perfectly well with polyester. But its great strength is its tendency to stretch out in the machine then relax in the fabric, and its relative stiffness and abrasiveness all make it inappropriate for use on soft or light weight fabric.

Cotton-wrapped polyester—By covering polyester filaments with cotton, thread manufacturers hoped to combine the best of both worlds into a true all-purpose thread. Polyester would provide strength and stretch, and cotton would provide a smooth, heat-resistant surface. Regrettably, what we get is often the worst of both worlds: a stretchy thread with an irregular surface. If it’s well made, it can serve as a good substitute for an all-polyester thread, especially since it comes in an extra-fine version, unlike polyester. But it’s not a substitute for all-cotton.

Silk—Filament silk thread naturally combines a smooth luster with elasticity and great strength, and it has the added ability to keep its shape when pressed, which makes it ideal for tailoring wool. Don’t use filament silk on lightweight silk fabric—it’s too strong and the filaments can actually cut through the fabric. Silk is a good choice for fine knit fabrics, and its slippery surface makes it a joy to hand stitch with; try it the next time you’re gathering by hand, and for basting. Unfortunately, some machines don’t respond well to its slickness, and it’s been all but impossible to buy (see “Options for thread” on the facing page for more on silk thread). It’s also extremely expensive and I am usually just as happy with cotton thread.

Testing thread

One of the difficulties in evaluating thread for a garment is the fact that most of the problems only show up in the completed project. It is the cumulative effect of the wrong thread that shows. As you sew the individual seams they may appear to lie fiat, but when you try the garment on, the seams appear puckered and stiff. The fabric will drape and give, but an inappropriate thread will not give with the garment when it's hanging.

Just as you test interfacing before you fuse it onto your project, learn to sew test seams with the needle and thread that you intend to use. Check a variety of threads sewn into the fabric on a strip at least 12 in. long with at least 2 in. between the seams. See how the different threads affect the fabric, and then press the seam and see how that changes the stitching. Try a variety of needle and thread combinations.

Begin by testing for quality in the thread before it's stitched into the garment. Pull and stretch it. How far does it stretch? Does it return to the original length? Does it change shape after pulling? Pinch the thread and pull it between your fingers, as you look at it closely. Is it fuzzy, flaky, smooth, or slick? Does it have slubs or chunks on the outside? Does it have rough or irregular areas? Bend it into a loop and check the flexibility. Does it stay looped or can it be creased on the end?

Obviously, it’s nice to find a very close color match in thread. but thread color is much less important than good quality and the right characteristics for your projects. If you’re having trouble finding a match, try matching the value rather than the shade. Often a neutral gray of just the right value will blend in perfectly with a variety of dark, pale, or bright colors in the same value.

Options for thread

The first place to look for an alternative to your fabric store’s selection of thread is at sewing machine dealers. They often have high-quality threads that show off the capabilities of their machines.

Mail-order and Internet-order sources—I investigated three types of mail-order thread suppliers:

Large fabric and sewing stores, Amazon.com or All-Brands, catalog sources for tailors and dressmakers, and thread manufacturers or importers. In each category there are more examples than I can possibly list, so the ones mentioned here are representative rather than exhaustive, with the exception of the manufacturers and importers; the two listed below are the only ones I found that sell directly to the public. Check out any tailors’ suppliers or specialized local fabric store or web site, as well as the ones visible in the ads running on the left and right-hand sides of this web page.

Catalog descriptions of thread can be very confusing, but they’re all trying to describe the same thing: the thread’s thickness, plus the number of strands, or plies, that were twisted together to make it, if that’s the way that thread was made. In the most frequently used convention, standard home- sewing thread is size 50, and the most desirable number of plies for garment-making is three, so a standard cotton thread is called “50/3,” or “size 50 3-cord,” or something similar. Smaller sizes are always higher numbers, and the number of plies is given, so a 60/2 is a thinner thread, with only two plies. If the thread is described with some other convention, you simply need to know what the equivalent to a 50/3 is.

Here are the variations I encountered. Size O is approximately the same thing as size 50, only a little bigger, and 00 equals a size 60. Silk and silk-substitute threads are usually named with letters: A and O are for hand or machine, and both are equivalents of size 50, A being a little thinner. Topstitching thread is size D, and buttonhole twists are E, F, FF, and FFF. Popular all- purpose threads packaged for home sewers often aren’t labeled for size, but they are usually thinner than standard cotton. Metrosene, Gutermann, and Molnlycke thread, the most widely sold long- staple poly threads, are all size 60/3; and Coats’ Dual Duty Plus, a cotton-wrapped poly, is slightly thinner than size 50 cotton. Dual Duty Extra Fine is slightly thinner than size 60.

Cotton thread—The best all- cotton threads for garment sewing are three-ply and mercerized. The most widely sold examples for home use are made by Coats, Mettler, and Zwicky, and all are 50/3s. None of these companies makes a thinner three-ply cotton in colors; most thinner cotton threads sold in fabric stores are the less strong two-ply variety, designed for machine embroidery or for sergers and blindstitch machines. Coats does make their three-ply cotton in black and white in sizes 40, 50, and 60, available by mail from them in 125- and 300-yd. spools. The tailors’ suppliers listed below sell 50/3 mercerized cotton, usually on much bigger spools or tubes, or on cones, for which you need a thread holder—about $5—from the same sources. Most have cotton in 60/3 as well, in many colors.

Polyester and cotton-wrapped poly—Among the widely available brands described by size above, only Dual Duty comes In a thread thinner than 60 (Dual Duty Extra Fine), but all come in a topstitching weight. They also come in larger spool sizes than you’re likely to find locally, although the bigger the spool, the fewer the available colors. If you’re tempted by a polyester thread you don’t recognize, make sure it’s long staple before you buy, or you’re probably asking for trouble. No doubt there are cotton-wrapped threads besides Dual Duty, but no one I called carried any alternatives.

Silk—There are a lot of differing opinions about when and if to use silk thread. The manufacturers and importers tend to think you can use it for anything, naturally enough, while most experts and notions buyers are much more cautious. For many years in this country, Belding Corticelli sold a filament machine silk that was so strong and smooth that it could actually cut through lightweight fabrics, so many experts recommended against silk, except in woolens. It’s no longer available, but others are (Kinkame, YLI, and Tire brands are all filament silk), and they are regarded with the same cautions in mind. Maggie Backman imports Tire silk and claims that because it's available in a wider range of thicknesses (the others are all size 50) and is engineered exclusively for machine sewing of garments, Tire can be used where the others can’t. She points out that Tire and other silks are widely used to sew garments in Japan. Tailors here also have always used filament silk thread in many weights, and it’s still used in the best factories on all weights of wool. It’s available from the sources below.

On the other hand, Gütermann has recently introduced a spun-silk thread which they claim answers all the objections to filament silk, because It is softer; Gütermann has been successfully selling spun silks in Europe for nearly a century. It’s available in a size 60 for machine and hand sewing, and in a thicker topstitching weight.

The final objection to silk is, of course, the cost—four or five times that of cotton—but few garments would need more than $10 worth of thread. So if the results are substantially better, it would be foolish to scrimp, especially if your fabric is costly. Are the results better? It’s a good question. I’d love to hear from anyone with experience on either side of the question, for inclusion in a future article.