My flute has become loose and I did a temporary quick fix with some tape. Do you have a preferred type of thread and wax? Where do you find it?
I use black silk thread and beeswax. You should be able to get the thread at any sewing store. Not sure about the beeswax, though, as I got it from a friend who does the “bee thing”.
Pat
I use bowstring wax (from archery supply shop). Mine is Fred Bear Bowstring wax, well over 30 years old, and still nicely soft in its tube. I wouldn’t be surprised if it was mostly beeswax. For thread I’ve used both silk embroidery thread and very fine polyester thread. I use a good amount of wax and relatively loose wrapping. I’ve never had a problem, though there are some authorities who insist that thread wrapping damages wooden flutes over time (do a search of the site for further info).
As a temporary fix, “in the field”, I’ve used dental floss. I suggest you keep some in your kit as it is a better choice than using tape.
I use polyester sewing thread (Gütermann, because it is very strong) and my own mixture of beeswax (from a local beekeeper) and jojoba oil (about 50/50).
Jojoba oil is actually a liquid wax, not an oil, and makes the mixture soft and easy to apply. I also add a few drops of essential oil ( lavender , bois de rose or ylang ylang) just to make the wax smell good. Because it only contains natural substances you can also use it as a lip balm. 
See my help-sheet on Thread Lapping.
A rider to one contribution above - “strength” is not what you want as the thread does not need to be under high tension, and it may be injurious to the flute for it to be so. Thread which absorbs the grease well and packs evenly, is not so soft as to wear away too readily but is not overly hard and which is not highly hydrophilic and liable to swell is what you ideally want. I would also avoid beeswax as it tends to become hydrogenated and to build up.
That said, have you established why your flute’s joints have loosened? Does it need hydrating? If it has been subjected to overly dry conditions and that is why the joints are loose, merely increasing the amount of lapping risks cracking of sockets if the wood reswells unexpectedly. Caution!
I haven’t. Perhaps I should place the flute in a box with a damp sponge for a while?
Anyone care to chime in on that? Should I put the flute in a box with a damp sponge for a day or so before futzing with the wrapping? I’m still playing it with the tape on it as of now.
Forgive me if this is all common ground that has already been covered a million times.. 
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It’s certainly worth a try - can’t hurt and may both solve the problem and show you need to consider the environment you’re subjecting the flute to. When I need to do that when visiting my parents in southern Spain I usually wet a folded sheet of kitchen roll and put that on a plastic lid inside a Tupperware type box with the flute sections.
12 hours or so hasn’t changed anything. I’ll let it go over night and check again in the morning.
Ralph Sweet recommended five ply wool yarn for the wrap and any lip balm for the wax. I got my yarn at Wal-Mart and a tube of Chapstick. Fixed the loose joint on my blackwood Sweetheart whistle. Burt’s Bees also makes a beeswax lip balm that’s readily available.
Jude
Any opinions on waxed dental floss?
L
I tried it when I first started out. It’s pretty hard, with no resilience, so it seems at the opposite end of what we want, which is something that won’t prevent the underlying wood from swelling, and has compression, allowing it to fit nicely even if the underlying wood swells or shrinks.
Now, I’ve been pondering the wisdom of humidifying the flute while the tenon is wrapped in thread. I suspect that’s just repeating what got us here in the first place. Moisture, either from playing or artificial humidification swells flute, but tenon thread resists expansion. As flute dries out, tenons compress under thread.
Shouldn’t we take the thread off, humidify the flute, hopefully restoring it towards original dimensions, let it then dry out again, hopefully to “set” the changes, then put the thread back on? A test would be to wind the original thread onto a piece of stick so that it doesn’t get lost or tangled. When subsequently wound back onto the tenon, is the joint now tighter, or just as bad?
Now, it’s very possible that just humidifying the flute won’t restore the original dimensions - I ended up resorting to steam in the experiments reported on my web page. Another option would be to dip the naked tenon(s) into boiling water for 10 minutes or so, then leaving it to cool and air for a few days. You might find this voids the manufacturer’s warranty…
Terry
Over the years I went through most of the above and then one day got cork put on my threaded flutes. Haven’t looked back since.
Clark
Was speaking to a Piper about this and he said they use a form of Hemp Thread, but agree with Clark the cork always seems to be cleanest and best option