Serger question: 3 or 4 threads?

[Izzybee]

when would you use 3 threads and when would you use 4 when serging?

[puddingpop]

I use 3 threads when I'm serging around the edges of woven pattern pieces -- say for like a blouse -- so that they don't fray while I'm attempting to sew the whole thing together with my sewing machine; this way I can press the seams open to avoid bulk.

I use 4 threads when I'm serging the seam itself and bypassing the sewing machine -- this makes for a sturdier stitch.

Hope this helps.

[Ackray]

I have never used 3. I use 4 to make the serged edge of fitted diapers.

[pageta]

Three when I'm doing a finished or decorative edge on one layer of fabric. Four when I'm sewing two pieces of fabric together.