There are so many myths regarding thread. Some are propagated purposely due to a financial motivation, others by misinformed professionals including store sales staff and repair technicians, and most by innocent people just passing on what they have heard.
Myth 1. Polyester will tear my quilt fabric.
Not true. If you have attended one of Bob’s seminars, you have seen hands-on proof that this is a myth. (If you haven't, please watch his thread therapy DVD ) Thread tearing into a fabric has nothing to do with the thread fiber type but with the strength of the fibers (both in the thread and in the fabric). Some cotton thread (such as glazed cotton) can be stronger and more abrasive than polyester.
Myth 2. My machine repair person said that I must use only ____ thread. (Fill in the blank with a brand name or cotton or poly, etc.)
Some have been told to use only cotton thread. Others have been told to use only polyester thread. I’m sure the person who says this means well. He/She probably just finished cleaning a machine full of horrible lint or other problems and intended to advise the owner to use a better thread. The advice may be spoken out of frustration or misinterpreted. Imagine a car company saying you must use only Shell gasoline because other brands will damage your car. It does not make sense. Quality is the key, not the type. Your machine is made to accommodate many types and sizes of threads. With the proper needle and tension adjustments, your machine should run any high quality thread. Don’t be stuck on one channel.
Myth 3. Using prewound bobbins will void my warranty.
Not true. Similar reasons as #2 above. I personally checked with machine companies and using prewound bobbins will not void any warranty. Most machine companies sell prewound bobbins. They are a wonderful convenience. Choose quality bobbin thread.
Myth 4. You must always use a 3-ply thread.
Not true. In most cases a 3-ply thread is stronger than a 2-ply thread. However, if the 3-ply thread is a lower quality product, it is possible than an excellent quality 2-ply thread is stronger and preferred for particular uses. The number of plies is not the critical point. The quality of the raw material and the processing techniques together determine how good a thread is. For example, consider piecing thread. The goal when piecing is to make a smooth seam without bulkiness. A thread with occasional slubs (clumps of excess thread or lint wound into the thread) will not create a smooth seam. A heavier-than-necessary thread will make a bulky seam. If you have a top quality smooth, slub-free, and adequately strong 2-ply cotton, the seams will lie flat, the points will meet, and there will be no bulkiness in the seams. Quality is more important than the number of plies.
Myth 5. Titanium-needles are so strong, that instead of the needle breaking when under force, it will break your machine.
Not true. If using a Titanium-coated needle posed a risk to a sewing machine, the majority of factories around the world which sew any garment, upholstery, quilt, or textile wouldn't use this modern marvel. Titanium needles are not made from Titanium, they are made from high-strength steel and coated with a thin layer of Titanium-nitride. This layer is almost like a ceramic substance and only 3-5 microns thick on a sewing machine needle. It doesn't add any breaking/tensile strength, but does increase the life of the needle several times due to advanced abrasion resistance.