I took this picture when I was half way through (before I started decreasing). I don't seem to have a picture of the final square scrubby but I think you get the idea from the photo.
Intermediate (advanced beginner)
Yarn: Red Heart scrubby 100% polyester, knitting needle US 8/5mm, weight 4
(the yarn i used is called almond. Unless you want your scrubby to look like a dog—and add some details like eyes and a nose, I recommend picking a different color. I wish I had at any rate).
Needles: 4 mm. (note this is smaller than the suggested size—for even tighter knitting)
Stitches you need to know:
k = knit
kfb = knit into front and back of same stitch
kb = knit from back
k2tog = knit 2 together
K1B = knit into stitch below (and current stitch together).
K1BBL: same as K1B, but knit from the back (into back loop)
K1B: This is what makes this dense. You will be knitting into the stitch from the row below and the stitch you would normally knit at the same time. Actually, the way I did it was knitting from behind. I’m sure it would work to knit (from the front)—which I did the first stitch of each row. And of course, knit from the back for the last stitch of each row.
For the LEFTY
1. going from below, put left needle into the purl stitch of the row below the stitch you will be knitting next.
2. place that purl onto your right needle.
3. knit that purl and the next stitch on your needle together. (I knit from the back).
That’s it. Now repeat into next stitch. If you do this correctly, you will have the exact same number of stitches on your needle as you started.
For the RIGHTY
1. going from below, put right needle into the purl stitch of the row below the stitch you will be knitting next.
2. place that purl onto your left needle.
3. knit that purl and the next stitch on your needle together. (I knit from the back).
If you’ve never done this stitch before, I recommend practicing with regular yarn. Scrubby yarn has all sorts of extra yarn pieces sticking out from it. This makes it more challenging.
Cast on 2 stitches.
Increasing rows
1: kfb kfb (now you have 4 stitches)
2: K1B, *K1BBL*
3. kfb *k* to last stitch kfb
repeat row 3 for all odd numbered rows until desired size (this one is about 8 inches on the diagonal)
4. K1B *K1BBL*
repeat row 4 for all even numbered rows until desired size.
once you reach the size you want:
odd row: knit across (no increase or decrease)
even row: same as row 4.
Decreasing rows
1: k2tog *k* to last two stitches k2tog (from the back)
2: all even rows same as row 4 above
all odd numbered rows same as decreasing row 1.
When you have two stitches left, bind off.
Finishing:
option 1: weave in ends. Done.
option 2: after you bind off, make an i-cord with three stitches for 2 inches and attach to your scrubby to create a loop for hanging it to dry. Then weave in ends.