I recently had the cork fall off a flute and decided to thread it. I had watched Jem’s tutorial and others with recommendations for wax and cork grease. I also watched a tutorial on dry threading recorder tenons by Patrick Von Huene. Having no time and feeling somewhat experimental I used two strands of separated DCM 100% cotton floss and used his, for lack of a better word, x style wrapping of dry thread. I am likely going to likely redo it Jem’s way when I have time and thought not adding any grease or wax could make things easier to unwind. My question is does the grease form some sort of moisture control protection, keeping the thread itself from getting saturated somehow? I have never noticed grease on the few threaded flutes that have passed through my hands. Is it just so well absorbed as to never be noticed? Or were these threaded dry originally?
Yes, treating thread wrappings with beeswax does reduce the amount of moisture they can absorb. And moisture absorption is a big problem for some thread materials, specifically cotton, and some flute woods, like boxwood or fruit woods.
The problem with dry wrapping using cotton thread is that it absorbs the moisture that comes from the bore when you play, and it expands when it gets wet. This can cause tenons to stick, and worse, it can accelerate problems of tenon compression. The effects of this have been studied in detail, and were first documented in the following paper by Claire Soubeyran (if you want to get into the details):
Terry McGee has also done some detailed studies on these effects.
Some people go so far as to suggest that you shouldn’t thread wrap tenons at all, and instead you should use cork. Personally, I read the results of these studies a bit differently.
If you look into the detailed results of the Soubeyran study, for example, you see that dry cotton thread has the worst results, in terms of tenon compression. Waxed cotton is only slightly better, silk is better still. Waxed silk wrapping has the exact same level of compression as cork wrapping, and even they are not perfect.
So, my take is that you really shouldn’t use cotton thread (because it absorbs a lot of moisture and swells up a lot). And even when using a less absorbent material you really should soak it in wax to reduce the amount of moisture it can absorb further.
Personally, I still thread wrap my tenons, because I prefer it to corking, for various reasons. I use silk thread which I soak thoroughly in beeswax. I also make most of my flutes from stabilized wood which doesn’t absorb moisture and hence doesn’t have the expansion and contraction cycle that leads to tenon compression.
By the way, this issue is discussed in more detail in this older thread.
Why not synthetic thread? There are some comparisons in a table here:: Moisture Regain and Moisture Content of Different Textile Fibers If I read it right the synthetic threads (except rayon which is a thing on its own) take up less moisture.
I asked the same question in the older thread on this topic. I do know that nylon has potential problems due to the fact that moisture causes it to increase in length (and lose its strength). Anyone who has camped in the rain in a nylon tent has probably experienced how much the flysheet sags as it gets wet, requiring the guy lines to be tightened. And how much it shrinks again as it dries.
With a nylon thread wrapped tenon the thread would have the potential to loosen when wet. If you wrapped it wet it would tighten a lot when drying. I haven’t actually experimented with this though. But this is the reason I asked about polyester in the earlier thread about his. Unlike nylon, polyester is very hydrophobic.
By the way, in the moisture regain article linked above, I think they are talking about moisture absorption from air while wearing clothing in different humidity settings, not about immersion.
During immersion, cotton holds up to 27 times its dry weight, whereas silk only absorbs 10%or so of its dry weight. Cotton is a highly absorbent cellulose fiber that swells. It is hydrophilic. Silk is a protein fiber that is also hydrophilic, but much less so than cotton.
Thanks for the details. What I did was temporary, and on a flute that was previously corked. So I may just go back to that instead. I do like the ease of thread so I may research silk.