Essentially there are 2 ways to create a thermal crochet stitch. I was first introduced to this technique over a decade ago. “Thermal” is worked one way, and today you can find it worked in a completely different manner. This is proves to me even more, that you cannot rely on the fancy names of crochet stitches, make sure and check the special stitches of a pattern.
However, I thought I would share what I have learned about this stitch. Basically a thermal stitch is one that creates a double sided fabric. Stitches are connected by working through the loops of 2 different rows to create the third.
Bottom Up -1 of 2 ways thermal crochet
I learned to connect these stitches from the “bottom up”. Insert the hook through the loop of the row 2 rows below upwardly and then through the front loop of the row typically be worked into. Yarn is wrapped around the hook and then pulled through these 2 loops. There is an additional yarn over, and pull through the last two loops; a single crochet thermal stitch is created. Learn it here.
The bottom up method creates a fabric that has the “front” or “right” side of the fabric facing outward, while the “back” of the stitch is captured in the center of the fabric.
Top Down -1 of 2 ways thermal crochet
The latest way I have seen this stitch explained, uses the same loops of the stitch rows has the base of the stitch, but instead works the hook down through the front loop of the regular working row and then through the unused loop of the row 2 rows below.
To prevent the stitches from twisting, the work is essentially worked “backwards”. Meaning that you are crocheting the fabric in the opposite direction from that which you usually do. This “top down” method creates a fabric that has the “wrong” of “back” side of the fabric facing outward with the “front” encapsulated in the center.
There are some slight visual differences with these methods, and the Bottom up approach tends to lend itself better to working in the round.
This is an interesting stitch, either way you work it. I am continuing to explore its possibilities.