The Ins & Outs of Grafting.
For example, you can use grafting to join two halves of a scarf where each half has been worked from the cast-on to the center, to join two short ends of a knitted rectangle to form a cowl, or to reattach a part of a garment (such as the lower portion of a sleeve or sweater body) that has been removed and altered in some way. And grafting doesn't need to be limited to stockinette stitch or even a single color. It can be used on almost any stitch pattern, from ribbing and seed stitch to cables, lace, and colorwork.
Because grafting is a seaming technique that mimics the structure of the knitted fabric--the way the stitches interlock--it is the most invisible joining method. But it can be somewhat trickier to master than other seaming methods. Not only does it involve working with live stitches, but the grafted row must also be adapted to the particular stitch pattern of the pieces that are being joined, which requires a certain amount of knowledge and skill. This is especially true with more complex stitch patterns.
In order to fully understand how grafting works, it's essential to understand how knitted fabric is created. The more you know about stitch structure and how grafting relates to it, the better you will be able to graft any type of seam you encounter.
Stockinette Stitch Structure
During the knitting process, new loops of yarn are drawn through existing loops (A). Because of the serpentine structure of knitted stitches, there are actually two sets of loops on every knitted row: one that runs along the top of the row (these are the loops that sit on the needle) and another set that runs along the bottom of the row (the loops formed by the running threads between stitches) (B).
Each new row of loops is drawn through the top loops of the previous row, and the top loops of each row interlock with the bottom loops of the row above it. In illustration C, one row in the center has been highlighted. Notice that each loop below the highlighted row is situated between two bottom loops in the row above the highlighted row; the top and bottom loops don't align vertically. If we follow the path the highlighted yam takes through the loops below and above it, beginning at the right-hand side, we can see that the yarn passes through the right half of a top loop of a stitch in the row below, then through the left half of a bottom loop in the row above, then through the right half of the next bottom loop on the same row, then finally through the left half of the same top loop in the row below as before. This sequence of four passes is the same for every stitch. (We'll come back to these four passes later when we talk about top-to-bottom grafting.)
When you graft, you use a tapestry needle and a strand of yarn to follow the same path that one row takes through the loops below and above it while simultaneously joining the live loops on the front needle to the live loops on the back needle. Because each knitted row has two sets of loops, it is possible to join either the top loops of one row to the top loops of another row or the top loops of one row to the bottom loops of another row, depending on the construction of the piece that is being grafted. With a pattern such as stockinette stitch, there is no noticeable difference between the two. The difference will be much more apparent when grafting a pattern such as k1, p1 rib that contains a mixture of knit and purl stitches across a row.
When you graft the toes of socks, you join the first half of the round to the second half of the same round, which means that you are joining the tops of stitches on the front needle to the tops of stitches on the back needle. This type of grafting is called top-to-top grafting. The same type of grafting can be used for shoulder seams, where the last row of the front is grafted to the last row of the back. The other type of grafting, top to bottom, more closely resembles knitted fabric that is worked all in one piece. When you graft live stitches to a provisional cast-on, you are joining the top loops of the stitches on the front needle to the bottom loops of the cast-on row (it is the bottom loops that are placed on the needle when you undo the waste yarn from a provisional cast-on). Thus, the direction of knitting on both the front and back needle is the same (D). This isn't the case with top-to-top grafting, where the stitches on the back needle are actually oriented upside down in relation to the stitches on the front needle. Not only that, but the pattern on the back needle will also shift to the left a half stitch in relation to the pattern on the front needle. This change in knitting direction and pattern shift from piece to piece in top-to-top grafting isn't too noticeable with stitch patterns such as stockinette stitch or garter stitch, which look the same whether they are viewed right-side up or upside down, and where there is no change in the pattern from side to side. But a rib pattern isn't so versatile; not only will it have a different appearance when viewed upside down, but its strong vertical lines will make the half stitch shift at the grafting line very obvious. We'll talk more about this pattern shift a little later. But first, there is another aspect of grafting that is affected by knitting direction: the number of loops that must be on the needle before the stitches are grafted.
Number of Loops On the Needle
As we have seen, there are two sets of loops on every knitted row: one that runs along the top of the row and another that runs along the bottom of the row. Although the two sets of loops may look similar, they are each configured a little differently. For example, if we compare the two sets of loops in illustration E, we can see that there are four top loops but only three bottom loops. Because the bottom loops fall between the top loops, there will always be one fewer loop on the bottom row than on the top row. There is also a half loop at each end of the bottom row. The half loops can be very useful when grafting stitches top to bottom. Not only do they help to anchor the first and last grafted stitch, ensuring that the edges will be nice and smooth, they also make it easier to align the stitch patterns vertically.
On the provisional cast-on row, one of these half loops is formed when the yarn is drawn up to work the following row. The other half loop must be created by threading the cast-on tail onto a tapestry needle and wrapping the tail around the knitting needle, then through an edge stitch to the wrong side of the work. Adding the second half loop will create an extra stitch on the needle, but this is okay. Unlike top-to-top grafting, you don't need to have the same number of stitches on each needle when grafting top to bottom.
Now we'll look at the impact that a change in knitting direction will have on the stitch pattern.
Illustration F shows the relationship between the loops on the back needle and the loops on the front needle during top-to-top grafting. The Xs indicate the loops that sit on the needles. Both needles have the same number of stitches, and all the loops on the back needle are shifted over a half stitch to the left so that the loops on the front needle will be situated between loops on the back needle.
Grafting can actually be thought of as creating two separate pattern rows: one on the front needle and one on the back needle (even though the grafted row is a single row). For example, illustration G shows how knit stitches are created when stitches are grafted on the front needle with the right side facing. For each grafted knit stitch, the yarn goes purlwise, then knitwise through a loop on the needle. The chart under illustration G shows this in two dimensions, with a rectangle representing each loop on the needle. The letters P (for purlwise) and K (for knitwise) represent the path the grafting yarn (shown by the arrows) takes through each loop. Illustration H shows the grafted knit stitches on the back needle, as viewed from the right side. The chart shows the grafting steps as they'd be worked with the right side facing. However, because the stitches on the back needle are created with the wrong side facing, the grafting steps must be reversed (going knitwise, then purlwise into each loop) to create purl stitches on the wrong side (just as when knitting stockinette stitch, you knit on right-side rows and purl on wrong-side rows) (I).
Illustration J shows the grafting for both needles combined into one grafted row. The purple portion shows where the rows overlap.
In top-to-bottom grafting, the structure of the knitted fabric is followed more closely than in top-to-top grafting. As a result, the loops on the front and back needles need to be set up in the same way as the loops above and below the highlighted row in illustration C from our discussion of knitting structure, with a half loop at each end of the back needle stitches (K). As before, the Xs indicate the loops that sit on the needle (notice that there are five Xs on the back needle and only four Xs on the front needle). In the chart, the rectangles that represent the loops on the back needle are drawn with a dotted line to differentiate them from the loops on the front needle. The grafting yarn will follow the same path as the highlighted row in illustration C, with four passes for each stitch (L):
1. Purlwise through the right half of the loop on the front needle.
2. Purlwise through the left half of a loop (or first half loop) on the back needle.
3. Knitwise through the right half of the next loop (or last half loop) on the back needle.
4. Knitwise through the left half of the same loop on the front needle as before.
These four steps are repeated for every stitch from the beginning to the end. The stitches are removed from the needle after Steps 2 and 4 and remain on the needle after Steps 1 and 3.
Grafting- K1, Pi Rib Top to Top
We have seen that when stitches are grafted top to top in stockinette stich, we are actually creating knit stitches on the front needle with the right side facing (by going through each loop purlwise, then knitwise) and creating purl stitches on the back needle with the wrong side facing (by going through each loop knitwise, then purlwise). Grafting k1, p1 rib top to top is simply a matter of creating knit and purl stitches on both needles (M). In the charts, the grafted purl stitches (as viewed from the right side) are shaded to differentiate them from the knit stitches. The charts make it easy to see at a glance how the grafting steps relate to the stitch pattern. The other thing that becomes clear when looking at the charts is the jog in the pattern between the stitches on the front and back needles.
Grafting K1, Pi Rib Top to Bottom
There are two ways in which grafting rib top to bottom differs from grafting rib top to top, and both of these differences involve the back needle. We've already seen that, when stitches are grafted top to bottom, there should be one more stitch on the back needle than on the front needle after both half loops (one at each end) have been added (K). When stitches are grafted top to top, there are no half loops to consider, so the number of stitches on both needles will be the same.
The other difference is where the transitions between knit and purl stitches occur on each needle. Looking again at the chart for grafting stockinette stitch top to top (J), we can see that the grafting steps alternate across each needle. Compare this to the chart for grafting k1, p1 rib top to top (M), which shows that there are two of the same grafting steps at each transition between a knit and purl stitch (or a purl and knit stitch). The chart clearly shows the jog that occurs when grafting k1, p1 rib top to top because the stitches (but, more importantly, the transitions) on each needle are offset by a half stitch.
In top-to-bottom grafting, the transitions between knit and purl stitches on the provisional cast-on row occur in the center of each loop because these loops are the strands between stitches on the needle. In other words, if you draw an imaginary line between a knit and purl stitch on the last row worked down to the cast-on row, the line would go through the center of a bottom loop, making each loop half-knit/half-purl, or vice versa. When these loops are placed on the back needle and configured as shown in illustration K, the transitions will align vertically with those on the front needle, as seen in the chart for grafting k1, p1 rib top to bottom (N).
The charts in illustration O show how the grafting relates to the first pattern row worked on the back needle above the provisional cast-on row and the last pattern row worked on the front needle. The four passes for each grafted stitch stay within the vertical transitions, without any jog. The knit and purl stitches that are created on each needle are independent from one another and can be mixed and matched according to the pattern that is being grafted. If you want to see how this works in practice, we've included a grafting chart with the Connacht Cowl (page 60) in this issue.
Caption: Top-to-top grafting (stockinette stitch)
Caption: Top-to-bottom grafting
Caption: Top-to-bottom grafting (stockinette stitch)
Caption: Top-to-top grafting (k1, p1 rib)
Caption: Top-to-bottom grafting (k1, p1 rib)
Caption: Top-to-bottom grafting (with first and last working rows)