Double jacquard knitting allows one to design and knit multiple color patterns without the worry of floats. The color changer (standard machines hold a limit is of 4 colors at any one time) and the ribber is required. The ribber knits the floats into the second layer of fabric on the ribber side, resulting in the term double knit. Often the main bed is set to slip throughout. Slipped (or first-row tuck) stitches become elongated until nonselected stitches knit off. The more the colors in any one row, the more all the stitches on the front face of the fabric must stretch in order to accommodate the number of colors laid behind in the backing fabric. The elongated stitches may allow for the other colors to be seen, and this is often referred to as “grin/bleed-through”. Different ribber settings may help with some of the elongation (depending on separation method) and grin through issues. The same principles used for DBJ separations apply to single bed multiple color slip stitch, and creating the initial swatches single bed can serve as a test for the DBJ pattern separation. In the series below some of the potential issues become obvious
the design repeat
The simplest color separation expands each row of the design to X times its original length based on the number of colors per row; in this case, 3 design rows expand to 6. In addition, in order to knit the fabric, the elongation function (X2) must be used, and each color for each design row will be knit twice, with color changes every 2 rows. This is necessary if the color changer is to be used since it takes 2 passes of the knit carriage to travel away from and back to it in order to pick up the next color. The result is a very elongated design. It is possible to knit the same motif without elongation, but then the yarn needs to be cut and changed on the appropriate side and each row, creating side edges not suitable for garments. One can separate any design with this method, and the motif may even have an odd number of rows. The sequence below is for the expansion of the first 2 motif rows
The graph below shows the motif in repeat, the next column the color separation, with expanded rows, and in the third, the black indicates the knit stitches (black squares on mylar, punched holes in card)
Testing the design single bed slip stitch: the resulting fabric is dense, with lots of floats, and narrow in final width, with little if any stretch. In the knit swatch: elongation is marked, would remain so even if the fabric were knit double bed and settings on ribber to reduce elongation were used
There are 2 other options for separating colors that deal with the problem of elongation, but they do not work on every design. The separation on the left is set up in sequential 2 two row units. In a 3 color pattern, each row of the design expands into 6. The selection row is made toward the color changer. The separation on the right also retains the knit scale. In using either one must often be willing to adapt and edit the original design motif. The total number of rows is the same as the previous method, but the sequence for color one is split as seen in numbers beside the color column in the chart. The selection row is made away from the color changer, knitting a single row in the pattern for color 1. In these separation methods, the motif must have an even number of rows
The respective resulting swatches: the elongation problem is solved, but the repeat is off in the upper third of the design. Some separation programs are able to scan through your design and locate the problem areas, even shuffle the order in which the colors are knit in order to allow the separation to work, but manual solutions may be quite time consuming or at times not possible
A redesign: one method to avoid pattern shift problems and ensure success is to use units in the design that are 2 stitches high, as seen in the motif and its separation below.
In knitting, the selection row is made toward the color changer. In rows where color 3 is not represented, only the first and last needles are selected, and manually pushed back to the B position. Eliminating end needle selection can cause problems at the outer edge of other colors, eliminating blank rows from graph and knitting would require much more attention to where in repeat one is actually working, and lead to possible frequent mistakes in color sequence.
the resulting fabric, knit, and purl views