Here is Day 7 from Jane’s TIAS. I have some close up views of the very last bit to show the SLT and how she is using it to get us to change colors back to the original color in this piece of the TIAS.
See how the new thread (white) is on top of the old red one? If you continue tatting a chain the new ds will be white and not red. If you DNRW and make a ring, the ring will be white also!
I have taken some pics of how this looks with some yarn so maybe it is easier to see what is being done (tatting with yard is interesting).
Once you cross your threads you can pull it tight.
Then if you continue to make a chain, your color has now changed! Simple right?!