Perhaps the biggest secret to success when it comes to sewing with silks and rayons is to make sure you are using the proper needles and thread. The exact weights and settings will vary depending on the fabric, but here are some general guidelines to keep in mind. Remember, taking 10 minutes to test before you start sewing can save hours of frustration later!
Needles: Not to be underestimated, selecting the right needle can have a huge impact on your results. Silks and rayons will usually require a universal needle, ranging from sizes 60 to 70, or a microtex needle if the fabric is densely woven. Use a new needle whenever possible to ensure it is as sharp as possible. The rule of thumb is that the lighter the fabric weight, the smaller the needle should be.
If you see any puckering to the left of the fabric as you sew, it can be an indication that the needle size is too large or too blunt. The same is true if fabric is getting pulled or pushed into the throat plate—this means that the needle is “pushing” the fabric rather than piercing it. Test different needles with your fabric until you find one that can sew a seam with no puckers or skipped stitches. Keep in mind that lighter weight fabrics also call for a shorter stitch length.
Thread: The most important aspect of selecting the right thread is its weight. Because lightweight fabrics will require smaller needles, the weight of the thread needs to be suitable for the size of the needle eye. Thread that breaks in smaller needles can be an indication that the thread is not fine enough.
Contrary to popular belief, you do not need silk thread to sew with silk. As long as the thread weight is suitable, you will be fine sewing with cotton or polyester thread too. Here are some pros and cons of different thread types:
Pins: Use extra fine or ultra fine pins, which are less likely to cause holes or snag delicate fabric. Test pins before sewing to make sure they will not leave permanent marks. If they do, try pinning parallel to the edge of the fabric within the seam allowance so holes will not show on the finished garment.
At this point, you’ve hopefully tested thoroughly and have your needle, thread, and machine settings all dialed in. This will greatly ease your sewing experience, but there are a few other helpful tips to keep in mind when sewing with silks and rayons:
Sewing: Special feet are not necessary to sew silk, but a walking foot (which adds a second pair of feed dogs above the top layer of fabric) can be very helpful for pulling fabric through the machine evenly. It’s often recommended for knit fabrics but for similar reasons can be great for slippery fabrics. One reason we love our studio Pfaffs is the IDT system, which provides all the benefits of a walking foot without requiring a separate attachment.
If you’re not using a walking foot and you’re having trouble with the fabric feeding evenly, you can try stabilizing the seam with a piece of tissue paper placed on the fabric, and sew as usual. The paper will help feed the fabric through your machine and tear away after. Likewise, increasing the presser foot pressure can make it easier for your sewing machine to “grip” lightweight fabrics.
While it’s usually best practice to backstitch all of your seams, it can be challenging with delicate fabrics. If this is the case, skip the backstitch and instead tie off seams with a small knot (like you would for the end of a dart). You can also decrease the stitch length right at intersecting seam lines to add stability to the stitch line.
Pressing: Like everything else, it’s important to test heat and steam settings on your fabric before taking the iron to your final garment. Make sure to press carefully and use a press cloth. Pure silk can generally take higher temperatures, but rayon can be very sensitive to heat. If you have chosen not to prewash your silk, skip the steam as it can stain the fabric.
Finishing: Lightweight wovens are especially prone to fraying, which means you should skip the pinking shears in favor of a more sturdy finish. If the pattern is unlined, consider using french seams, overlocking, or another finish where the raw edges will be hidden or tucked away instead.
Finally, go slowly! Don’t expect to be able to sew a silk dress as quickly as you’d sew a cotton one. Try to take pleasure in the process—the results will be well worth the extra effort!