I was asked to repost this. This is an easy way of tying blocks to yards or mast. I have also used this to tie blocks to the underside of tops.
I start out with thicker thread. A little trial and error with different threads to get the look I want. Notice I have the thread folded three times and use a clip to hold the thread tight.
I use smaller thread to wrap around the thicker thread. I start out with a slip knot tied in the thinner thread, and stick the loop and loose end of the thicker thread through the knot.
The thinner thread has two ends. The end that pulls the slip knot tight and the end the pulls the loop through the knot.
I pull the loop tight against the thicker thread and use a second clip to hold the thinner thread in place.
I start wrapping the thin thread (The end that pulls the knot tight.) around the three layer of thick thread and the loop of the thin thread.
I make 7 to 10 or more wraps. Trail and error to get the look.
While wrapping and after, you have to hold the wraps to keep them from unwinding. Remove the one clip. Take the end of the thread you've been wrapping and pass it through the loop of the thin thread.
Still while holding the wraps to keep them from unwinding, pull on the other end of the thin thread to pull the loop tight around the end of the thin thread. Pull the thin thread tight but not too tight. If is too tight, it will be hard to pull the thicker thread through. Also, as you pull on the end of the thinner thread it will pull the loop and the other end on the thin thread into the wrap.
You now have a loop and a loose end of thicker thread sticking out each end of the thinner thread. Pulling the loose end on one side pulls the loop in on the other side. Put a block in one loop and pull the loop tight.
Slip the other end over a yard or mast. You can also start out with the loop already around something.
Pull that loop tight.
Add a drop or two of CA glue, and when it is dry snip of the loose ends. This picture shows two block tie to a yard.