In Karen Loomis’s PhD thesis (volume 3, p.379-380) she prints two photographs of a shim from tuning pin hole no.23 on the Queen Mary harp. One shows the shim extracted; it is made from a split section of a feather quill.
On my replica, pins 29 and 30 have needed shimming for some years now. I had originally tried paper, and subsequently sheet brass, but I was inspired by this discovery, to pull the pins and try quill shims.
I am preparing for Wednesday’s concert here in St Andrews. I am going to play a programme of “Ceòl Rígh Innse Gall”, my speculative re-imaginings of medieval West-Highland ceremonial music. This project is still very much a work-in-progress, and I am still thinking hard about how this music should work, and what sources of inspiration and musical material to raid.