Stitches
Slip Stitch: Joining, Seaming and Fabric
The slip stitch is three tools wearing one name: a join (closing a round by slip stitching into the first stitch), a seam (slip stitching two edges together for the strongest, firmest crochet seam), and a fabric (rows of slip stitches through the back loop make a dense, elastic, knit-look rib). One rule governs all three uses: work it looser than feels natural — the slip stitch has no height to absorb tension, so tight slip stitches strangle rounds, pucker seams and make fabric rows nearly impossible to work into.
Most guides file the slip stitch under “basics”, teach the join, and move on — which is how crocheters end up mid-pattern discovering it is also a seam, also a fabric, and also the reason their hat brim finally stretches. It is three distinct tools, and they share exactly one operating rule.
The rule first: loose, always
Every other stitch has a post — a little tower of worked-off loops — that absorbs tension differences. The slip stitch has none: whatever tightness is in your hands goes directly into the loop, and an over-tight loop is a locked door for the next row, a strangled round, a puckered seam. Work it looser than feels right; for slip-stitch fabric, going up two hook sizes is standard practice, not cheating.
Job one: the join
At the end of a round: slip stitch into the first stitch, done. It is the mortar between rounds in everything worked circularly — granny squares, hats, amigurumi with joined rounds. Kept relaxed and singular, it disappears; worked tight or doubled “for security”, it builds the tell-tale knot column up the side of the piece. The coaster pattern’s rotating-start trick exists to scatter exactly these.
Job two: the seam
Two edges held together, slip stitches through both: the firmest seam crochet has. Bags, baskets, structured blanket-strip joins — anywhere strength beats suppleness, this is the answer, and the joining-granny-squares comparison prices it against its alternatives (fast, sturdy, most yarn, visible ridge). For a drapey cardigan seam it is honestly too rigid; that is mattress stitch territory.
Job three: the fabric
Rows of slip stitch through the back loop only produce something that surprises people who have crocheted for years: a springy, deeply ridged rib that stretches and recovers like knitting. It is the standard crochet solution for hat brims and cuffs — worked sideways as a band, then joined. Slow per row, but a brim is three inches, and no other crochet fabric does elastic this convincingly.
The stitch that patterns treat as punctuation turns out to have a full grammar. Learn the loose-tension rule once and all three jobs — plus surface slip stitch, the draw-on-your-fabric bonus in the tips — come along free.
Notes
- The universal rule: whatever the job, slip stitch looser than instinct says. The stitch has no post — no height — so there is nowhere for excess tension to hide. Many crocheters go up one or even two hook sizes whenever a pattern turns to slip stitches; for slip-stitch fabric, two sizes up is the standard advice, not a workaround.
- For the round-closing join: insert into the top of the first stitch (both loops), yarn over, pull through everything in one motion. If your joins climb into a visible seam-line of knots, you are working them tight and doubling them — one relaxed slip stitch per round, and consider the invisible needle-join for final rounds where it shows.
- For seaming: right sides together, through both layers, one slip stitch per stitch pair. It makes the firmest seam in crochet — ideal for bags and structured pieces, deliberately rigid for drapey garments, where mattress stitch is kinder. The seam ridge lands on one side; choose which by which way you hold the pieces.
- For fabric: rows of slip stitch through the back loop only (BLO) produce a springy vertical rib remarkably close to knitted 1×1 rib — the standard crochet answer for hat brims and cuffs that must stretch and recover. It is slow per row but shallow per row; a brim band is only ever a few inches.
- Surface slip stitch is the bonus fourth job: with the yarn held behind the fabric, slip stitch through it along any path and you draw a chain-look line on the surface — free-hand lettering, plaid lines over a plain blanket, outlines on colourwork. Same stitch, used as a pen.
Common questions
What is a slip stitch in crochet?
The shortest stitch there is: insert the hook, yarn over, and pull through both the fabric and the loop on the hook in one motion — no height-building pull-throughs at all. Because it adds almost no height, it works as a connector and a mover: closing rounds, seaming, travelling across stitches without adding fabric, and, worked in rows, making a dense elastic fabric of its own.
How do you slip stitch two pieces of crochet together?
Hold the pieces right sides together (for a hidden seam), insert the hook through the matching stitches of both layers, yarn over, and pull through everything — one slip stitch per stitch pair, worked loose. The result is the strongest, most rigid crochet seam: perfect for bags, baskets and blanket strips, less ideal for garments that need the seam to flex. If the seam scallops or puckers, it was worked too tight.
Why is my slip stitch so tight I can't work into it?
Because the stitch offers no post to absorb tension, every bit of tightness lands in the loop itself — and then the next row cannot get in. Fixes, in order: consciously pull each loop up before moving on; go up one to two hook sizes for slip-stitch sections; and for BLO fabric, keep the fabric relaxed on the hook rather than stretched. Tight slip stitching is a habit that one deliberate loose swatch usually breaks.
What is slip stitch fabric good for?
Ribbing, above all: slip stitch through the back loop makes a vertical rib with genuine stretch and recovery, the closest crochet gets to knit rib — hat brims, cuffs, waistbands, and whole beanies for the patient. The fabric is also dense and windproof, which suits mittens and winter accessories. Its cost is speed: rows are shallow, so the same inches take more rows than any other stitch.
What is the difference between a slip stitch and a single crochet?
One pull-through. A single crochet pulls up a loop and then works it off in a second step, building a small post; a slip stitch pulls through everything at once and builds essentially none. That missing height is the point: sc makes fabric wherever it goes, while sl st connects, travels and edges without adding bulk — and each is wrong in the other's job.