Fabrics
Knits
Determining the amount of stretch in knit Fabrics - Fold the fabric so it is in layers. Hold about 10 inches of fabric along the cross grain. stretch the fabric. Take the length of this stretched fabric and subtract 10. divide that number by 10. Multiply by 100 to convert the decimal point to a percentage. That is the percentage stretch of the fabric.
When Sewing with knits its best to use a pattern designed for knit or stretch fabrics with a minimum of seems
It is best to use long needles because they are sometimes hard to find in the fabric.
Hints when working with knits: Use a nap (one-way) layout, placing the tops of all pattern pieces so they face the same direction. Use all purpose polyester or cotton covered polyester thread When sewing them a stretch needle like a size 75 is recommended (these needles have rounded points to prevent skipping a stitch). Use a strait stitch slight longer than conventional stitching (approximately 9 stitches per inch, or a setting of 3.0 on many sewing machines), slightly stretching the seam as you go. For very stretchy knits, use a narrow zigzag stitch. If the pattern includes a 5/8 seam allowance trim the edges to 3/8 inch after stitching, then sew the trimmed edges together with a zig-zag stitch. When adding zippers, buttons and buttonholes its best to stabilize both seam allowances with a fusible interface strip of a cloth that is lighter weight than the knit, then add the zipper, button or buttonhole.
Jersey Knits - These are sometimes called "single knits." Jerseys are known to stretch to the "right" side when stretched along the cross grain. They are made from 100% cotton, rayon or wool; cotton/polyester blend, or other fiber blends. The stretch range is 25%-50%. Usually are soft and drapable
Interlock Knits - These knits look the same on both sides and are technically a type of double knit. They are made from 100% cotton, 100% wool or a wool/cotton blend. Interlocks stretch approximately 50%. It is necessary to pretreat these knits to avoid shrinking after the garment is finished
Double Knits - These are stable knits with lengthwise ribs on both sides. This makes both sides look the same. They are made from 100% cotton, wool, polyester, acrylic or blend. They usually stretch under 25%. They retain their body and shape well.
Stretch Velvet - This is a pile fabric with a plushable nap on the face and vertical ribs on the back. Stretch Velvet is usually 100% polyester or other blend. It stretches about 25%. Caution needs to be taken because it is a pile fabric and you must make sure that both top and bottom layer feed evenly.
Warp Knits -These knits are less stretchy, they are stable lengthwise but have just a little crosswise stretch. This makes them best used with patterns designed for woven fabrics. Warp knits are known for their great texture. Note: It is best to pretreat these, washing them if they are washable in cool water and drying in a cool drier. then steam press to eliminate uneven edges. If not washable steam press fabric to treat it
Weaves
Weaves are the staples of most sewing and are usually the easiest fabrics to work with. These cloths generally have less than 20% stretch. While its impossible to list everyone one of the wide variety of woven cloth I will mention a few of the main types.
Courdoroy - This cloth is woven by using differing thread sizes and dropping one out at a regular basis. These cloths are general made of cotton, polyester or a blend. These clothes range from the bulky cords every knows to the new micro cords common in high fashion today.
Broad Cloth - This is the basic woven cloth found in sheets, many shirts, dresses and so forth. It is a simple and strait forward weave and can be made of just about any fiber.
Muslin - This is technically a type of broad cloth, but because of its especially loose weave it has its own properties. Muslin is inexpensive loose broadcloth of cotton, which is lightweight considering the rather large fibers it uses. When sewing muslin make sure to keep a tight stitch that is not too small, usually a stitch length of 2 and 3/4 to almost 3.
Denim - This is the cloth we know from "blue jeans". Denim is a usually heavy cloth woven with a faint directional grain, usually from cotton or a cotton/polyester blend. Recently it is finding more uses as mills experiment with lighter weight denim with tighter weaves and finer fibers. Denim made of silk has even made it into use in the area of high fashion.
Oxford - Is a type of broad cloth with alternating thread color and sizes. This gives it a distinct feel and is most often found in shirts.
Flannel - Is a woven cloth of alternating horizontal vertical and diagonal fibers. The use of fine cotton threads and the multi directions of the weave makes this cloth very soft, and it softens more over time.
Interfacing
Fusible Interfaces - These interfaces really iron on and fuse to the fabric, making it a simple to apply support and interior finish.
Traditional interfaces are bound on with a glue type stabilizer and are good for large pieces, but with all the fusible interfaces are rarely used now.