The Double Foundation Chain is a wonderful vintage stitch
that you may not see very often. It is also known as the Double Base Chain
Stitch. However, once you use it, you will undoubtedly agree
that it is very useful. You can also use this stitch to create a nice
rope.
Crochet 2 chain stitches, insert the needle downwards
into the left side of the 1st chain stitch, throw the cotton forward, draw
it out as a loop, wind the cotton again round the needle and draw it
through the two loops on the needle, * draw the cotton as a loop through
the left side of the last stitch (see illustration), wind the cotton round
the needle, and draw it through both loops on the needle. Repeat from *
till the foundation chain is long enough.