Working with Knitted Fabrics
Knit fabrics have become a staple in sewing, combining comfort and easy care with style. Choosing the right knit and proper handling and sewing techniques are the key to getting beautiful, professional results. Below you will find more about the construction, handling and sewing of knits.
Knit Fabric Construction
Knitted fabrics are woven from a continuous length of yarn that is manipulated into interlocking loops to create a flat fabric. The looped construction provides the fabric with much more give and flexibility than its more rigid woven cousins. There are two types of machine knitting construction: WEFT and WARP
|WEFT KNITTING was developed to copy the look of hand knitting and employs a continuous length of yarn to form crosswise rows of loops that interlace row by row to produce a flat fabric. Weft knit fabrics include:Jerseys or Plain Knits have a flat surface that looks like a series of interlocking V-shapes (knit stitches) on the front, backed with short, horizontal loops (purl stitches)
Double Knits are made on a special interlock machine that uses two yarns and two sets of needles to draw the loops through from both directions. The result is a thicker, firmer, more stable knit the resists runs.
Rib Knits are made with alternating sets of knit and purl stitches in the same row. On the surface of the fabric the knit stitches form a raise vertical ridge while the purl stitches recede. The number of knit and purl stitches in the pattern determines the width of the ridges. Ribs provide a snugger fit than other knit and are often used at cuffs, necklines and hems.
|WARP KNITTING can only be accomplished by machine and utilize multiple yarns that are wound parallel to one another on a warp beam. As the yarns feed into the machine they form loops in the lengthwise direction. Each yarn is controlled by its own needle and progresses in a zig zag pattern, interlocking with the other yarns as it moves along the length of the fabric. Warp knit fabrics include:Tricot Knits have more stretch in the crosswise direction and has a fine crosswise rib on the wrong side of the fabric.
Raschel Knits have a textural appearance and can be made with varying weights of yarn. A fine chain of yarn usually runs the length of the fabric, stabilizing the more openly knit textured yarns. Sweater knits are often this type of construction.
Using the Pick-A-Knit® Rule
Because knit fabrics have give, garments made from knits usually stretch enough that no closures (zippers, buttons, etc.) and fitting darts and seams are needed. Patterns for knit garments generally use what is called the Pick-A-Knit® Rule, which is a guideline for how much stretch is needed in the fabric to obtain the construction and fit intended. The Pick-A-Knit® Rule is found on the back of the envelope, and looks similar to a ruler:
Take your fabric and place it at the beginning of the black area of the guide. Pull the fabric from the end of the black area until the end of white area of the guide. This is the amount of stretch the fabric will need for that pattern. If your fabric doesn’t stretch to the end of the white area, the fabric is not suitable for that particular garment and may not fit as designed. The Pick-A-Knit® Rule may vary from pattern to pattern, so always test the stretch of your fabric before cutting and sewing.
Layout and Cutting Tips
|Use a double thickness cutting thickness layout, except for sweater knits which require a single thickness layout.|
|Use a “with nap” cutting layout. Knits frequently have one-way shading that may not be discernible until the garment is finished. Many knits also have directional motifs or knit-in designs.|
|Always position the pattern pieces so the greatest amount of stretch goes around the body.|
|Use pattern weights rather than pins for sweater knits.|
|Choose a lightweight nonwoven or stretch interfacing. Avoid fusibles, which do not give with the knit fabric. When applying interfacing to knits, apply to facings rather than the body of the garment.|
|Use scissors or a rotary cutter for cutting knits.|
Needle and Machine Settings
|Use a ballpoint or stretch needle in a medium weight size: 75/11 HS to 90/14 HS (Schmetz) or 11 to 14 Yellow Band (Singer). Using a standard needle may result in skipped stitches.|
|Use a narrow zig zag or stretch stitch, which will give with the fabric when wearing.|
|Decrease the pressure of the presser foot for heavier knits; increase the pressure for lightweight and tricot knit.|
|Sergers are a great way to sew knit fabrics – the stitching has inherent give and the seam allowances automatically get trimmed to a neat, narrow finish.|