The Shetland wool would take a simple spit-splice beautifully, but I am concerned about how that kind of join would hold up when it comes to blocking the shawl. I know for a fact that spit-splicing works just fine, but I don't want to test that theory to the max. The prospect that severe blocking will pop the joins and spill my hard-earned stitches all over the floor makes me weak in the knees. So for better or worse, I'm using a belt-and suspenders combination of Russian Join and Spit-Splice.
First, the end of the first ball is looped around the start of the new ball. A needle is threaded with one of the ends.
Next, the first end is woven back on itself, catching the yarn with itty bitty stitches. (If the join were not going to be felted together with the spit splice, I would make the weaving a bit longer.)
The same technique is applied to the other end. Both ends are now interlinked, with the ends woven back on themselves.
The free ends are then carefully trimmed at a steep angle (not shown). With embroidery scissors, I fray them back so they can feather back into the strand.
Now for the fun "spit splice" part. I stick the woven section in my mouth and get it wet. (EWWW, you say? The shawl gets washed later!) Then I rub the section briskly between my palms for a minute or two until the join is nice and even. You can see the result here. The join is in the yarn right above the scissors, between the bird's tail and the beak. I bet a skein of sock yarn that you'll never find one of these joins in the finished shawl!
Back to knitting...