A delrin flute is not subject to cracking due to changes in humidity and temperature and does not need as much care or attention as a wooden flute does.
There is a small pot of grease included with each flute for greasing the threaded tenons and the metal tuning slide.
Vaseline can also be used for the threads – though some brands of vaseline can be a little too thin. The metal slide needs a thicker grease than vaseline. The grease supplied in the pot is made from beeswax and vaseline by simply melting the two together in a microwave oven and adjusting the relative quantities until the required consistency is obtained. A ratio of about 50/50 of vaseline to beeswax is a usually a good mix to start from.
The joint tenons are threaded with waxed thread which is the traditional manner of sealing joints on woodwind instruments and is the easiest for the player to maintain. The thread used is the commonly available thin polyester sewing thread. For those with experience of wooden flutes and recorders, joints on a delrin flute do not swell and contract with changes of humidity and temperature.
However, it is generally better to prefer the polyester thread over a cotton thread as the cotton can swell when wet if the joint is not waxed or greased properly and the joint could then become difficult to separate – but even then there would be no risk of cracking the delrin. The tenons should be greased regularly as this helps to keep them from leaking air as well as allowing them to be joined and taken apart easily. Of course they should be kept free of grit.
If a joint becomes too loose, it may be necessary to add some thread by winding it on to the tenon. Conversely, if a joint becomes too tight even after greasing, it will only be necessary to remove a little of the thread. New thread should always be carefully greased. The end of the thread has been left loose and you only need to run a fingernail across the threads to find it.
Note that the metal tuning slide on my flutes must be kept greased as is usually the case with the slides on 19th century flutes. If the slide is not greased it will leak air and the performance of the flute will suffer. This is different to the slide on the modern silver flute which should never be greased.
You should only need to grease the slide if it starts to become either too stiff or too loose. About once or twice a year should be enough. To grease the slide, simply separate the head from the barrel section and use a clean cloth to clean off the old grease from both metal tubes. Then rub a little grease on the outside of the inner tube and also on the inside of the outer tube. Test the fit. If it is slightly loose, add more grease. If it feels a little tight, take off some of the grease. The slide needs a thicker, stiffer grease than vaseline. Finally, be sure to clean off the grease which has squeezed out of the end of the two slide tubes inside the barrel.
Make sure that grease does not build up inside the bore of the slide and also make sure no grit or dust gets in the tuning slide as it can cause scratches and these will in turn cause air leaks.
The head and barrel should always be kept joined together as this prevents grit from getting into the slide.
If your flute comes with a white delrin stopper in the headjoint, it will have a rubber O-ring in a groove on the outside. If you remove the stopper for some reason, you should wipe a touch of grease on the outside of the O-ring and also a little in the bore where it sits before replacing it. If you put too much grease on, the stopper will slide too easily and you will need to take off some of the grease. There is also a rubber O-ring on the endcap which needs greasing occasionally.
If the delrin stopper needs to be moved, this should be done with a wooden dowel with a large enough diameter so the stopper won’t get marked – 14mm to 18mm will do. Make a mark at 20mm from one end and use that to reposition the stopper correctly in the head.
If the flute has a cork stopper, the outside should also be lightly greased if it is removed.
The stopper should never move too easily as it is essential that it remain in its correct position.
Note that it is extremely important to position the stopper or cork reflector correctly in the bore when replacing it.
The flute will not work properly if this is not done right.
Here are the correct positions for the reflector (the stopper or cork) in the head-joint on my flutes – this can vary for different makers:
- Pratten and Rudall & Rose types – 20mm from the centre of the embouchure hole.
- Boehm bore type – 17mm from the centre of the embouchure hole.
The cork in the headjoint of the aluminium flute with delrin head does not have a hard facing and if it needs to be moved, this should be done with a wooden dowel which has a large enough diameter – around 14mm to 16mm diameter will do. Make a mark at 17mm from one end of the dowel and use this to reposition the cork correctly. The standard metal cleaning rod used for Boehm flutes is too thin and can easily damage the cork facing.
If you ever do use a cleaning stick designed for a Boehm flute on a conical flute, you need to remember not to use the mark at 17mm to set the stopper position.
Occasionally the surface of the delrin body will become a dry, greyish colour. When this happens, just rub a little of the grease or vaseline on the exterior and then wipe off all excess until “dry” and this will restore the original dark appearance. The same can be done with the bore using a cloth on the cleaning stick. It is important to make sure afterwards that there are no accumulations of grease in the embouchure hole or toneholes.
The embouchure hole and toneholes should be inspected regularly and can be cleaned out with cotton buds.
As with any musical instrument, it is not a good idea to leave the flute in a car on a hot day.