I hate sewing crochet panels together. Hate is probably too strong a term - "actively dislike and avoid" is more accurate. It's not that I never assemble by hand sewing (I even like hand sewing), but maintaining consistent tension over the entire length of a seam with hand stitching that has no inherent elasticity is difficult, and I find it's prone to puckering or distorting the crocheted stitches.
Crocheting the panels together makes me happy because the interlocking loops are much more elastic and move and drape well within the total garment - as long as your slip stitches are relaaaaaxed.... The goal of the slip stitch seam is to allow the seam to drape as part of the general fabric of the garment, so the tension of the slip stitches must match that of the edging stitches ( I most often use double crochet for the edging stitches as described in earlier blog post CT#2).
My Spider Lace Maxi Dress uses this feature seam, both to connect the Spider Lace V-panel to the bodice as seen in this photo, and to elongate the visual effect of the split in the skirt. My hooded Tunica Geometrica which was published in the US magazine Crochet! (Autumn 2016, Volume 29, No.3) is essentially motifs and dc edged panels, all joined together with the flat slip stitch seam technique. My patterns One Sleeve Poncho and Post Apocalypse Tee (available on my store Ravelry Peppergoose Designs) also utilise this join, and my Baby Hoodie Pullover (in issue 67 of the UK magazine Simply Crochet) uses both feature and flat slip stitch seam techniques to assemble the bodice and sleeves.
For both Flat and Feature slip stitch seams, in order for it to drape well (after blocking), I want to avoid bulk, and this is achievable by working into one loop only of the matching edging stitches of each panel. So on to the "how to:"
My swatch is edged with dc in Yarn B: Scheepjes Our Tribe Pistachio as described in the earlier crochet tutorial (Crochet Techniques #2). There are three dc at each corner and a stitch marker has been placed in each corner dc. I have purposely omitted one dc on two of the sides so the seams will be out by one dc in order for me to show my "Fudging it" instruction. The top and right hand side each have 27 dc, and the bottom and left hand side each have 28 dc. (If I had completed it correctly, there would be 28 dc counting from corner stitch to corner stitch on each side, as per stitch chart shown in CT#2).)
First, the Feature slip stitch seam (and Fudging it when the front panel edge has more stitches than the rear panel edge).
Second, the Flat slip stitch seam (and Fudging it when the back panel edge has more stitches than the front).
SLIP STITCH TENSION TIPS
It's super important that the slip stitch tension for the seam matches the drape of the fabrics you are joining together. To help your slip stitches "chill out":
Don't seam when you are running out of time.
Chill yourself first - take a few deep slowing breaths before you start the slip stitches.
Complete the entire seam (and the matching seam on the other side of the garment) in the same session, and check that they end up the same length and degree of stretch before continuing with the next step in the pattern.
Try a bigger hook size; the key is to let the hook diameter determine the loop size and concentrate on not tightening the stitch after pull through.
MOST IMPORTANTLY, before you start the seam, ensure that the stitch count of the edged panels to be joined are at least within a few stitches of each other. You can fudge about 1 stitch difference for every 12-15 stitches of seam and get away with it. Spread them out across the seam length to avoid a bump forming to distort the seam line. Don't use a fudging stitch in the first couple or last couple of stitches, as it doesn't get visually well absorbed into the general fabric.
I hope this helps! Next CT blog entry I will go over how I sew my tails in, and how I block the finished garment.