Hancock's Garment Marking Wax / Tailors Wax also known as London Wax Crayons are suitable for use on wool or worsted materials and are usually removed from the material by a warm iron.
Available in Blue, Red, Yellow & Black.
Photograph for illustration purposes only.
Be sure to test the wax on a spare piece of fabric before using to ensure that you can remove the mark after completing your work.