Underside couching: setting up an experiment

Today starts the last week of my 10-week Medieval Goldwork Course. It has been an exciting journey for all who participated! And although I will need to tweak some bits of the course, it is my pleasure to announce that the course will run again from 6-9-2021 till 13-11-2021. Sign-up will be Tuesday 1st of June 19:00h CET. This leaves me with enough time to order in materials and send them out to the participants in time. And between now and the 6th of September, I will be re-filming parts of the course with new materials, update the hand-outs and conduct a few experiments in my search for materials that come as close as possible to the medieval originals. First up is underside couching. Very little has been written on the exact materials being used in this Opus anglicanum goldwork technique. Somewhere in late summer, Tanya Bentham's book on Opus anglicanum will be out and I can't wait to see what exact materials she uses for successful underside couching. In the meantime, join me in my own experiments!

When you see people recreate pieces of underside couching, they often work directly on a linen background. However, a lot of Opus anglicanum was worked on a silken twill fabric backed by linen (see for instance the famous Jesse Cope). When you look at the detailed pictures of the Jesse Cope, it becomes clear that the silk twill used is of a heavier variety. But how heavy is heavy? Whilst silk twill is readily available in many colours today, getting your hands on a heavier version isn't so easy. And although the course sample of underside couching worked on a flimsy version of silk twill does work, I would love to see what results can be got by using a heavier silk twill fabric. I will therefore compare four weights of silk twill in my experiment.
Above, you see my slate frame fully dressed with a natural 40ct linen. On the linen, I appliqued the four squares of silk twill. Normally, I would use polyester buttonhole thread to set up my slate frame. But as there was no polyester thread in the Middle Ages, I decided to have a go with linen thread. I used Goldschild Nm 40/3 to attach my embroidery linen to the twill tape. That worked very well and the thread was strong enough. The big advantage of using linen thread over polyester thread is that the linen thread is rougher and thus keeping tension on your stitches is much easier. I also used the same thread to stitch on the twill tape onto the sides. However, the thread broke as it could not withstand the high tension. Switching to a stronger linen thread (Goldschild Nm 11/3) brought the solution.
Now that my frame is all set up, I can start the actual experiment. I will test several materials: silk twill weight, linen couching thread and gold thread. Although underside couching with the Goldschild Nm 40/3 works, I want to try a two-ply linen thread (the Goldschild thread is a three-ply thread). The original Opus Anglicanum embroideries were, however, worked with a two-ply linen thread. But again, getting your hands on a good two-ply linen thread is more difficult. What I have been able to get my hands on is real goldthread. Not gilt, but real gold. Not with a polyester core, but with a real silk core. This goldthread comes much closer to some of the goldthreads used in the medieval period (the others were made with animal gut as a substrate for very thin strips of gilded silver; unfortunately, no one can recreate these today). Next week, I'll update you on how my first experiments went!