I do the same as Im but my "tacking" thread is soluble thread so it just washes away when I wash the completed quilt. I just have to remember to keep my bobbin of soluble thread packed away from my other bobbins so I don't accidently use it for other sewing...yikes! It is very sensitive to moisture so I have to keep it packed in a sealed plastic bag.
It doesn't like like damp fingers on it to thread the needle either