Not all Polyester Threads are Equal

Sailmaker's primarily use polyester fiber threads. They are extremely strong and durable in outdoor applications and are dimensionally quite stable, i.e., they will not shrink or stretch enough to create problems. But it is not enough to simply specify a polyester thread.

As is often the case with synthetic fibers, the manufacturing process permits a widely variable thread type. The fibers can be produced with a "spun" or fuzzy surface or with a very smooth surface. The spun fiber is used in the construction of thread for dressmaking because it sews better—the fuzzy surface tends to pull through tension devices in a more consistent way than a hard, smooth, and rather brittle polyester does. But this spun thread is not nearly as strong as the smooth type. As a result, its use is rightly limited to dresses, kites, and the like.

There are two main categories of "smooth" polyester fiber thread: soft finished and bonded finished. The bonded version is especially treated to protect it from heat buildup and to improve its sewability—a coating is added that makes the thread slide more easily over metal parts. This bonding makes stitch tension more controllable.

Cheaper polyester thread, even the bonded variety, does not have the same sewability as that which is more expensive especially in home sewing machines. We have tried many thread companies in the past 26 years. One brand stands out above the others—Heminway and Bartlett manufactured by the Barbour Co (Now Coats Thread). Their bonded Dabond (polyester) thread has set an industry standard because of its high strength and controlled stretch, its stability in sunlight (UVR) and its resistance to needle heat, abrasion, saltwater and mildew. It will very seldom fray at the needle eye, and its bonded finish is so consistent that machine tension does not have to be continually adjusted.

As a rule, you will use about 10 yards of thread for each yard of sailcloth in zigzag mode. This provides some extra for sewing errors.

GORE-TEX ® \ Tenara™ Thread--guaranteed for life

We do not know why but the W. L. Gore company has changed the name of their expanded PTFE synthetic fiber sewing thread from GORE-TEX to "Tenara". It is the same high strength thread that for over ten years has proven to be unaffected by exposure to UV radiation, cleaning agents, pollution, saltwater, air, rain and snow. It is expensive but worth it in warm climates where canvas projects are left on year round and thread tends to rot. Tenara has the following lifetime warranty: "...Tenara sewing thread...will not be damaged by exposure to sunlight, weather or water during the life of the fabric with which it is used. This warranty covers all marine applications except sails...."

Tenara M1000 is similar in weight to V-92. Its breaking strength is 8 to 10 lbs. vs. 14 lbs. for V-92 but M1000 does not lose strength over the years.

Use a #18 needle with M1000. We have found that this thread sews very well. But there are some tricks. The most important trick is to change the orientation of the needle (only possible with industrial machines). In the case of our Ultrafeed machines, insert the needle so the eye of the needle is slanted from 10:30 to 4:30 (pretend the needle is at the center of a clock when viewed from the front of the machine and directly above the needle). This thread also does not usually require as much upper tension as our normal Dacron thread.

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