Hard string padding (goldwork)

Hard string is used as the base over which metal threads are couched to form patterns. These patterns can take the form of chevrons, diamonds, stripes and so on, or can be more complex, in which case they are known as basketweave. When using gold, it is advised to soften the harsh white appearance of the string by dyeing it, generally using tea. Once it is dry, run it gently through some beeswax to help make it a little more malleable. If you are using silver, the string can be left undyed.
See the entry for basketweave (goldwork) for how to couch the metal threads.
Method
Using a single waxed machine thread in a fine needle, couch down the string, starting in the centre of the shape.
When working the couching, place your stitches at a distance of approximately 3mm apart.
Trim the string at the edge of the shape
Finish the ends of the string by putting a stitch lengthways over the end, before adding another couple of couching stitches. This will act as a bridge to prevent the ends flattening.
Continue couching lengths of hard string down securely making sure that the distances between the pieces of string are even. You can use another piece of string as a spacer to ensure an even gap.

Embroidery Techniques
Related Stitches
Identifying Hard string padding (goldwork)
Generally not seen as a stitch in itself, it is used under metal thread as a padding and can be identified as a set of strings held together and onto fabric by a row of threads looped around the string and through the fabric.
References
-
Various Authors, The Royal School of Needlework Book of Embroidery (2018) , p.225
Examples of Hard string padding (goldwork)
Goldwork sampler
Sampler
Fleur de lis with hard string padding