How long a piece of elastic for prefitteds?

[ustasmom]

Excuse me if I sound silly, but:

How do you determine how long the elastic should be?

And how do you sew with elastic or Lastin? I have a machine that does a 3step zigzag but I have no idea what to do.

[2devils_1angel]

depends on who you are making them for.
for ds2 I use his premiums with organic cotton elastic (3/8") (i dont like lastin)
6.5"
I encase it (i prefer casings)
with the dipes for the new baby i have been experimenting with her preemie prefolds (have not go to her infant ones yet)
umm I think I used 4.5" of 3/8 elastic.
some i enacsed top to bottom and some i have only put the elastic about 3" from each edge.

You might want to measure your childs legs or mark where the front and wings wrap when the prefold is on your child.
I used a combination of ds2's measurements aand seeing where his prefolds overlap.

[babyblueeyes]

I sew mine with a 3-step or regular zigzag in the seam allowance before I turn, but I don't measure the elastic first. I tack it down at one end and zigzag it on pulling it tight as I go, tack it down at the other end and cut. I would guesstimate 6" or less needed. Oh, and I use 3/8" polybraid. I don't care much for lastin for dipes.