what is a zig-zag stitch?does it require two thread sources?what are its advantages over straight stitch?

Answer 1

It's done on a sewing machine. Only difference is a straight stitch goes like this :-----
and a zig-zag goes like this: /\/\/\/\/

It's good when doing applique, or when there is a risk of the garment fraying. The shorter the stitch length, the closer the stitches. You can also adjust for width, so that it can be narrow or wide.

Answer 2

Hand Embroidery - it can be done with one thread - depending on how you handle the needle.

Machines will use two threads to do a zig zag stitch.

It offers some stretch when done as a short, narrow stitch on a machine as a seam on knits or a bias cut fabric.

As an edge finish (along a cut edge of fabric) it can prevent the fabric from fraying (coming unwoven) - if you've ever seen what happens to a torn or cut piece of denim when it is washed - you know what fraying looks like..........

It can be used to stitch a cut out piece of fabric to a larger piece (applique) - done with a wide stitch and very short stitches - it is called "satin stitch" and will prevent fraying, the piece changing shape too drastically, and and secure the two pieces together.

You can apply elastic to a piece of fabric and allow it to stretch without using an enclosed casing if you zig zag it down - check underwear, swimsuits, and waistbands on pants or skirts for various ways to use a stitch that has some stretch to it or the difference between a stretch stitch or a casing.

The casing completely encloses and hides the elastic - and can be sewn any number of ways - the underwear may have exposed elastic secured only at one edge and the swimwear will have elastic zig zagged or serged (special machine using three or more threads) to the edge with one or more lines of straight stitching holding it so that only a folded edge of fabric shows. A zig zag stitch can be used for that stitching as well - depending how stretchy the fabric is and what machine(s) you might have available.

I've also seen a loose zig zag used to temporarily secure fabric pieces together to test size or the placement of a patch pocket or applique on a garment. The larger loose stitches going back and forth were easier to remove than smaller straight stitches.

Answer 3

No, it's a basic stitch with one strand. It's generally stronger than a straight stitch. You can decide how wide you want your zigs and zags to be, and how long the stitch length should be. The narrowest of both will be a buttonhole or satin stitch. For regular seams, I use the 2nd setting for both width and length.
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Answer 4

number one!! straight stitch is 2 interlocking threads with the thread lined up. pne stitch right after another.

number two!! zigzag stitch is just like it sounds. it is 2 interlocking threads but like a Z it goes back and forth. It is very handy for overcasting raw edges of fabric, for sewing on elastics, for putting a cord on a fabric without stitching into the cord.

It just does a different type thing all together.

like having both an oven and a microwave. or a freezer and a refridgerator.