Here is the second “Tech Talk” from Jude Skeers, our guest in October 2015. As noted in the first Tech Talk article (posted January 15) he has sent these articles to Roisin to be shared with us. 
The article was first published in the Australian magazine yarn which you can see at the store.
If you haven’t tried Double Knitting, Jude includes a pattern for a headband at the end. Only 19 rounds…

Double Knitting
By Jude Skeers
Double Knitting is the knitting of two layers of fabric at the same time on one set of needles. Double Knitting can be tubular (and as such can be used to knit the arm of a jumper); it can be sealed at one end (to knit pockets on a cardigan or coat) or sealed at both ends. Double knitting can be knitted flat, knitting back and forth on straights needles, or it can be knitted circular.
The most concise definition of Double Knitting comes from Rae Compton in The Illustrated Dictionary of Knitting (1988), “Double knitting, or the knitting of separate layers of fabric, both sides of which show stocking stitch, can be worked with a special combination of slipped stitches and yarn held to the front.” Compton recommends doing Double Knitting on either double pointed or circular needles. The use of one, or more than one, coloured yarn would have an influence on the choice of needles to be used.
Mary Thomas in Mary Thomas’s Knitting Book(1938) refers to Double Knitting as “A Tubular Fabric constructed on two knitting pins.” Belle Meyers in Knitting Know-How: An Illustrated Encyclopaedia (1981) refers to the weight of Double Knitting, “You can knit stitches that are of double thickness. Such stitches can be used to make heavy jackets or coats without using bulky yarn.”
In a row of Double Knitting only half the stitches are knitted. Every second stitch is slipped with the yarn passing down the centre of the fabric. The fabric created by Double Knitting is usually stocking stitch. This doesn’t always have to be the case. It is possible to use any combination of knit and purl in a double knitted fabric. In the case of knitting the sleeve of a jumper, it is possible to knit a rib pattern for the cuff.
A variation on plain Double Knitting is sometimes referred to as Two Coloured Reversible Knitting. The first book on Double Knitting that I added to my library was Jane F. Neighbors’ Reversible Two-Color Knitting (1974). It details all aspects of two coloured reversible knitting including two coloured Double Knitting. Not all the patterns in Neighbors’ book created a double thickness fabric, but the chapter that does is titled Reversible Geometrics.  All of her double knitted patterns use two colours. She uses the technique to bring the colour at the back of the fabric to the front and vice versa. You can use this method to knit a red tree on a white background and on the reverse side have a white tree on a red background. She doesn’t have separate colours on each side but brings the colour from one side through to the other. This negates the pocket that usually occurs with Double Knitting.
Compton writes, regarding two-coloured double fabric, “a pair of double-pointed needles or circular needle make it possible to work a double fabric with one colour used for the one side and another used for the other side or lining. Although both sides are quite separate, the ends are joined.”  
A recent publication is M’Lou Baber’s Double Knitting: Reversible Two-Colour Designs (Schoolhouse Press, 2008). She writes, “Double knitting creates a reversible two layer fabric; both sides show only knit stitch. The purl side of the two layers face the inside, and there are air pockets between them…When you work a two colour design in double knitting, the two layers are interchanged at each colour change. Because you use both colors to work each pair of stitches, there are no strands across the back of the fabric.”
Double Knitting is alive and well on Ravelry. A simple search of the words Double Knitting results in 72 pages, which includes the full gambit of patterns. I have found Double Knitting to be excellent for the bands on hats. I first started using this technique in the early nineties and I have been using it since that time. I have been able to use the technique to knit a hat band that will not stretch out of shape and become too loose. I have found very few other uses for double knitting, as I have found it to be too heavy and inflexible. I have included with this Tech Talk my design for a double knitted headband.
Yarn 2 balls of different coloured 12 ply yarn
Needles and notions 6mm (US 10) OR 6.5mm (US 10.5) 40cm circular needle
Abbreviations MC=main colour; CC=contrast colour; wyif=with yarn in front; wyib=with yarn in back; sl=slip
Head Band
Using MC and circular needles cast on 88 stitches. Join to work in the round being careful not to twist sts.
Round 1:  (CC) *wyif, P1, wyib, sl 1, repeat from * to end.
Round 2:  (MC) * sl 1, wyib, K1, wyif, repeat from * to end.
Rounds 3-7:  as rounds 1-2 (finishing round 1)
Rounds 8-9:   (MC) as round 2.
Rounds 10-16:  as rounds 1-2 (finishing round 1)
Rounds 17-18:  (MC) as round 2.         
Round 19:  (MC) *wyif, P1, wyib, sl 1, repeat from * to end.

Cast off loosely