A sturdy double-faced, double-thick type of crochet that's an old favorite with those in the know.
Sometimes it's simply called "potholder stitch", but so are other kinds of stitches. It's more of a method than a stitch, so I call it the Stitchmerge Method.
Two rows are crocheted together as you go. My version is more dense, thick, and fine-grained in texture than what is currently called the “Waffle Stitch” technique.
Pictured is a striped potholder crocheted with scraps of plain cotton yarns. Behind it is a messenger tote I crocheted in the same stitch, but with very thick (Chunky or Bulky Weight) wool yarn. It's a perfect stitch for these and many other projects such as rugs, hooded scarves, and slippers. The rainbow colored one is a soft neckwarmer.
This project will get you started on a simple square of the simplest version of the double-faced stitch. Once you know how to do it, you might be able to see for yourself why it is more than a stitch, it's a whole method.
Make a slip knot leaving a 4"/10cm yarn end and place on crochet hook. Chain 19, or desired width.
Row 1: Sc (single crochet, or UK: double crochet) in both top loops of the second chain from your hook and in both top loops of each chain across, chain 1, turn: 18 sc.
Row 2: Sc (i.e. dc) in the back loop only of each sc of row: 18 sc.
Notice the ridge of front loops that you didn't crochet into? These will matter in Row 3. Chain 1, turn.
Now notice that the ridge of front loops are at the back of your work. These are the "unworked loops" of Row 1 stitches.
Row 3: Insert your crochet hook in the back loop only of the first stitch AND in the unworked loop of the first stitch of Row 1, yarn over hook and pull through these two stitches, then yarn over and pull through the two loops on your hook to complete a sc (dc). *Sc (dc) together the back loop of next the next st and the free loop of the next st in the row below, repeat from * in each st of row, chain 1, turn: 18 sc.
The upper blue strip in the photo is crocheted correctly. Notice that you only see the backs of the sc (dc) stitches in every row. In the bottom half of the photo, notice that the stitches look different. This is because you're seeing the *fronts* of the stitches in every row. This results in a much thinner, bumpier, and limp fabric. To me it's reminiscent of a "waffle weave" cloth.
Final Bind-Off Row: Chain 1, turn, slip stitch together the back loop of the first st and the unworked loop of the first st of the row below, repeat for each st across.
For a potholder, chain 8 or so and slip stitch in the last slip stitch made to form a chain loop for hanging.
Fasten off and weave in ends.
Pictured is a screenshot of my crochet newsletter issue #6 on this wonderful stitch. Read the issue here: http://eepurl.com/bzO8z .