With the weather changes between winter and summer my pipes joints need tightening. What is best to use - unwaxed hemp, waxed hemp,
dental floss? Should all the old windings be removed first? What is the
best way to wrap the thread so it doesn’t bunch to the top of the joint the
first time I piece it together?
Whenever I need to add binding (not very often, thankfully) I use waxed hemp. I’ve heard that for connections that need to move (drone slides, chanter tops, etc.) it’s better to used waxed thread of some sort.
Actually, I understand that it is better to use a non waxed thread/hemp. You want those joints to slide, and the wax can impede this function. Waxed thread is better to use with non moving joints as it’s adhesive quality tends to keep these joints secure.
I think JES is right. This yellow waxed hemp seems to be sticky - no good for moving parts. The wax from candles however seems to help gliding. Here´s my best bet (that´s what I always did): I wrapped those slides with any kind of normal plain hemp, used some glue, waited till the other day to dry and then rubbed some wax from candles on top to provide sliding.
Cheers,
Hans
Newby alert
I use waxed cotton thread.
Avoid Beeswax as it is a a very hard wax and will act as an adhesive causing problems.
A softer oilier wax is that used on small round cheeses. It is red in colour and does not set hard thus sticking the chanter to gether.
Cotton darning thread will adsorb the oil and make for a smooth sliding joint.
I have removed all of the old thread and used waxed cotton, build up the waxed cotton until the two parts are a light push fit then add a few more windings at the bottom end to provide a very small amount of taper to the joint.
works for me.
What I have done in the past is to bind with plain hemp until the joint was very slightly tight (but not too much so), then I rubbed a little (not too much mind you!) lip balm (chapstick) on the threading. That was two years ago and I haven’t had to redo it. The joints still work very nicely.
And no chapped joints as well !! Great.
Living in Florida might have some impact on which wax to use.
… there is that. 
Well that’s weird. When it changes from winter to summer things expand, and I have to remove hemp, not add it. Must be the Rhode Island microclimate.
If the ‘thing’ that expands is the windcap then the joint will loosen, I would guess it depends on the windcap material, wood, brass etc. and the coefficient of expansion of the different materials.
I recommend the red cheese wax/cotton it is excellent.
The solution is identifying the source of the problem. As stated above, if it is shrinkage/expansion of the part of the pipes, you adjust the hemp.
I think in most cases it the absorption of ambient moisture by the hemp (spring - summer) or drying the hemp (fall -winter) that is tightening or loosening the connections. Hemp is very vulnerable to dramatic changes depending on the amount of moisture. So, stabilizing the hemp would be a solution.
How could that possibly be done? Well, adding wax in one really good solution. The wax isn’t there for stickiness or slidation, but to make the hemp less susceptible to changes in the ambient moisture.
Best, John
There are a variety of waxes to use depending the needs. I often use my board wax, not the paraffin wax that is used as a base coat, but the good wax that helps your feet stick. I use a cold water wax called Viagra. As the label state “it helps you stay up longer.” This is a good soft wax.
Take Care Dudes.
I will definitely reiterate the point of not using waxed material - A well known Aussie piper managed to snap the top of his chanter while forcefully trying to twist off the windcap that was stuck to his beautiful Woofe chanter. When I met him and he looked at my chanter, he got straight onto cutting off the waxed thread and replaced it with thin cotton thread. Since then, I’ve used plain cotton thread to fill the chanter top out and put a tiny dot of superglue where the thread ends to keep it from unravelling. The thin cotton allows you to slightly fill out uneven areas for a perfect and tight fit without any sticky grab on the windcap.
This reminds me of a similiar thing I´d like to post here: For restauration purposes I had bought this lovely old boxwood ivory trimmed flute (Goulding). It had not been played for decades and it had stuck joints. You could twist the parts but could by no means get them apart. The waxed hemp had gone bulky. What to do? A friend of mine asked on a flute forum and someone had a solution: Alcohol. I only used Methylene (for starting charcoal grills - it is called “Brennspiritus” over here - I did not have the heart to pour alcohol into flute joints instead of into the mouth) but it also worked. After several trials (carefully, step by step) I managed to get it undamagedly apart.
Cheeringly,
Hans
I have had this swelling on my Highland pipes. Where I could twist joints but note take them apart. But the hemp was not waxed.
Being able to spin the joint without being able to remove it is due to not having attached the thread to the wood on the tenon. If the joint is not moved for a long period of time, the thread may become stuck to the sliding (outside) part of the joint. This is what black wax is for. It is applied to the thread for most of the first lap and the adhesive quality of the wax binds the wrap to the tenon. Then if the joint becomes stuck, at least it will not spin. If I have a number of layers to wrap, I apply bee’s wax to all but the last two wraps. The yellow stuff sold for GHB use is called hemp, but is linen thread, dyed yellow. Sometime ine the 1930’s, hemp became illegal, so flax was substituted. As flax may rot in a wet blown pipe or flute joint, real hemp (cannabis) can be used as it will not rot. I find the GHB “hemp” to be too thick for the smaller UP or NSP joint wraps. It is the same as #8 or #10 shoe thread (linen or flax). I use #16 linen or hemp thread. I prefer hemp as it has longer fibers and is stonger than flax for the same diameters. Don’t you prefer hemp for your joints? 
I make a joint “grease” for metal slider joints buy melting wax with some olive oil. Bee’s wax will harden over time. Cheese wax, board wax and microcrystaline wax can be used as well.
Well Ted, you are close to the source for the cannabis. I know the growers are not known to be too friendly though.