Make sure to weave your thread ends in well so they don't work loose when washed. One way to start is to weave the needle into the part you are starting with then do your stitching over the woven thread. Have never heard of anyone pre-washing rickrack before. We are still using dishtowels embroidered 20 years ago and no threads have come loose, altho they are large cotton dish towels not tea towels.