I have a quick video tutorial on how to do a Russian join when you are attaching a new ball of yarn to your project. I have been using this technique recently on both my current project, Owls, and my last sweater, Agnes. It is a slick technique and then you don't have to weave in ends later.
One thing to note is that you could dampen the joined section with warm water and roll it in your hands to felt the fiber together a bit. I didn't do that but it would secure the ends a little more. I did felt the ends like this on the Agnes sweater which I made with Quince & Co.'s Puffin. It is a single ply yarn and felted very easily.
Either way it works great and I hope you enjoy!
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