A simple way to achieve this look and it will also stiffing up the thread or sting but still leave it so as you can shape it to what you need. Go to a iron monger's and buy a bar of bees wax at the cost of about £2.50. Get an old pot one your wife uses no longer and melt the bees wax dip the string or thread allow to dry and is cold to the touch about 20 mins and that's all you need to do. The bees wax will last for years.