Tutorial: loose CO on 2 needles

My favorite elastic cast on is to simply cast on holding 2 needles together (or alternatively using a bigger needle): hold the two needle points tight together and cast on normally around them. When all stitches are cast on, remove one of the needle.

This cast on has been used by generations and generations before us.

I´m however perplexing to see more and more posts on social medias, explaining that this cast on is not elastic at all, but makes looser stitches. And proving their point by showing how the yarn used for the knots (that would be the yarn hold on the thumb) is shorter than the yarn used for the loops (the yarn picked or thrown, depending if you are knitting English or continental).

Although it´s true that the knot uses less yarn than the loop, this is a knitted CO and the yarns are interlooping with each other. If you stretch your knitting on the needle, the loops will be the right size and there will be more space between them, hence an true elastic cast on. I hope I made a point!