Most new sewing machines will have an automatic polyester setting, which usually works just fine to accommodate any type of polyester. If your machine doesn't have automatic tension settings, the upper tension will usually sit around a 4.
To test if the tension is correct, insert a bobbin in the bobbin case. Then hold it up by just the thread, the bobbin case shouldn't move. Give a little jerk on the thread and if the bobbin case slides down slightly, then the tension if perfect. If it drops freely, then it's too loose.
Across the 3 major brands I checked, the standard tension you need is 4, and the standard stitch length is 2.5mm. This is a good starting point for medium weight cottons like poplin and shirting. Choose a shorter stitch length between 1.8 – 2.5mm for lightweight cotton (eg. voile).
Generally, lightweight polyester fabrics require a size 11/75 or 12/80 universal needle, while medium to heavyweight polyester fabrics are best sewn with a size 14/90 or 16/100 sharp needle. You'll need to use a size 18/110 or 20/120 needle for extra heavyweight polyester.
Polyester makes a strong durable thread suitable for all types of sewing. Polyester thread doesn't shrink or fade when washed. And polyester thread doesn't produce a lot of lint, which helps keep you machine clean. Most of the “all purpose” thread at fabric and craft stores is 100% polyester.
Most new sewing machines will have an automatic polyester setting, which usually works just fine to accommodate any type of polyester. If your machine doesn't have automatic tension settings, the upper tension will usually sit around a 4.
Gütermann 100% polyester thread is an all-purpose thread that comes in a vast choice of colours and is widely available. You can use it for machine sewing as well as hand stitching, and it will work with most fabrics.
100% Polyester. Thread thickness # 40. Recommended for use with needle size 90-110.
Polyester is far stronger than cotton, and as a result, you can find this thread in significantly smaller sizes than cotton will be available in because the thread will still retain its strength, even at a super fine size like 100wt.
For example, Size 92 polyester has a 14.5 pound tensile strength; Kevlar in that size has a 30 pound tensile strength. Also, Kevlar only stretches 5% before it breaks.
Poly strings lose tension extremely fast, both statically (after stringing but before playing) and dynamically (while playing). They need to be replaced frequently, or you will lose power and control.
Thicker thread should require more tension to avoid puckering lightweight fabrics, but this is often just what you need to avoid issues. A heavier thread in the top and bottom will increase both tensions, and you'll probably need to set a lighter tension to accommodate heavyweight fabrics.
If you notice your thread looping, knotting, or fabric is puckering, you may need to adjust the sewing machine tension. Also, uneven, unbalanced stitches that don't lie straight on the fabric are a good indication that you need to make a tension adjustment.
Needle thread tension is too loose
The needle thread needs to be tightened if the stitching thread shows loops on the underside. On the other hand if the needle thread is too tight, it will pull up the bobbin thread and also show it on the topside.
The cons of polyester are mostly environmental, such as high energy and water consumption, pollution, and inability to biodegrade. But there are material cons as well, such as a higher likelihood of pilling, running, and pulling.
Polyester. Polyester is known for its strength, durability, and low shrinkage and stretch. It's the most common thread for outdoor applications. Compared to nylon thread, polyester thread has superior resistance to UV rays and moisture, but much of its strength is lost after prolonged exposure to sunlight.
This makes polyester thread a better use for stretch knit fabrics. The thread also is more resistant to abrasion, mildew, and sunlight than cotton. The downside however, is that polyester thread is generally thicker, kinks more easily, and will melt at high temperatures.
Gutermann Sew-All thread is the go-to thread for every serious sewist. It's ideal for both hand and machine sewing on all fabrics and seams regardless of stitch type. Gutermann Sew-All is strong, durable and reliable without fibre lint and seam crimping which can be apparent with inferior threads.
Gutermann 50wt Sew All Polyester Thread – Red Rock Threads.
Medium-weight polyester threads are the preferred choice for many sewers as a general-use sewing thread for garment sewing, bag sewing, and much more. In lighter weights, polyester threads can be used in a bobbin or as a blind stitch thread—they're even strong and smooth enough to use in a serger!
While mixing cotton fabric with polyester thread won't make that much of a difference, you may experience different amounts of shrinkage between the cotton and polyester. Cotton will shrink at a higher rate than polyester.
It is not a problem to mix fiber types, cotton thread on top and polyester thread in the bobbin, or thickness, 40 wt. thread on top and a 50 wt. thread in the bobbin.
Nylon thread has the best sewability. It is also a bit stronger than polyester and resists abrasion better than any other fiber. As a result, nylon thread is great for use on products that are subject to abrasion including shoes, bags, boots, furniture, footballs, saddles, etc.