With some motifs, the last picot to be joined ends up in just the right place and it's easy to complete the round. For right-handed people, that's when the picot is on the left side of your working thread. Just grab the picot and make the join.
However, on some motifs, the last picot is on the right side of the working thread when you're ready to make the join. The first time I came across this, I merely folded my tatting over so that the picot was in the right place and made the join. Oh, I was unhappy when I found what it did! When I flattened the piece, the picot twisted!
Here's how to avoid this mishap.
You will need a small crochet hook to do this. When you're ready to make the join, fold your tatting over so that the picot is in the right place to make the join. Put your crochet hook through the picot from the back, grab the working thread, and pull it through. Finish your join, then turn your tatting flat so you can double-check that the picot doesn't twist.