Yes, there is actually Silk thread - YLI ( my favorite) has a great color assortment of silk threads. I also have quite a few from Superior Threads. I love appliqué with silk thread.
It could be you are cutting/ using too long of pieces of thread- the longer your hand stitching thread the more tangles- problems. 18" is about the longest you should use. I don't use Mettler thread for hand work - for me it's been too aggravating- I save it for machine piecing, only have it when someone sends/ gifts it to me.
Try actual silk thread you will find it a huge difference.