A simple 1 lb cut of white shellac will act as a great thread preserver and will seal your wood inserts too. What is shellac and what is a 1 lb cut? I'm glad you asked. Shellac is material collected off trees in India and Asia, it is goop from bugs. Woodworkers and instrument makers have used it for centuries. You purchase the shellac flakes and add it to methanol or ethanol or similar alcohol spirits. There is lots of information on the internet about mixing shellac The flakes have a useable life of 2-3 years and when mixed with spirits, a shelf life of about 6 months. The one lb. cut refers to the percentage of flakes vs. spirits, see below for a small quantity of 1 lb. cut.
This works well for me, 14.5 grams of white shellac flakes mixed with 1/2 cup of ethanol.
Thanks to Jim Payne and Hal Bacon for the recipe and give it a try, you can thank me later.