A little about threads
Gold threads are expensive and can generally be bought only from specialist needlework shops and online-dealerships such as Dinsdale Embroideries. DMC/Anchor metal embroidery flosses are much cheaper and can be used instead of fine metal threads for large areas. Unfortunately there is no substitute for the larger purl or rococo threads or for gold braid. Goldwork is not, even now, an inexpensive art. ?

Originally the couching threads were silk, but normal embroidery floss works just as well and has the advantage of being available in many different colours. Whichever thread is used, it must be covered in a layer of beeswax both to strengthen the couching thread and to prevent any moisture within it from tarnishing the metal.

Very fine metal thread is usually used double rather than single and, if strong and fine enough, can also be used as a sewing thread passing through the material. This is a later technique, devised only when the technology for making very fine metal wires had been perfected.