Sticking pads can be the bane of the woodwind player's life. Having said that, it's something that affects players in varying degrees. Some hardly notice the occasional sticky pad, others find it compromises the playability of their instrument to such an extent that it's almost impossible to rely on the instrument in any real capacity.

So what's the answer? Well, you'd have thought the solution would be to replace the pad - and where the pad is old and evidently worn this is often the best recourse - but more often than not the pad that sticks is in good shape...new, even.

There are several factors that cause pads to stick. The first, and most obvious, is that they get wet in use. Granted, most of the moisture found in the bore of an instrument is condensation - but it carries with it fats and sugars that have been dissolved in the airstream. There's also a certain amount of saliva that finds its way into the bore too.
Another factor than can cause a pad to stick is excessive natural oil present in the pad skin - a problem mainly confined to new pads of the cheaper variety.
A combination of these two factors over a period of time can lead to a build-up of general crud on the pads ( and the tonehole rims ).
I would consider the above factors to be 'chemical' in nature - there are 'mechanical' factors than can lead to sticky pad problems too.
The most likely reason is insufficient spring strength. This is typically seen on BisBb and G# keys, where the key's spring is rather too lightly tensioned. While most of us would agree that a light action is a 'good thing', it's possible to overdo it and have certain keys 'undersprung'. You might be surprised at how common a fault this is, and where rolled or wide ( i.e. Martin saxes ) toneholes are in use the problem can be particularly acute due to the increased surface area of the tonehole rim. Increasing the tension of such springs by even a tiny amount can make a considerable impact to the problem of sticking pads, and with barely any detriment to the overall feel of the action ( in fact it can often improve it ).
Other mechanical factors include rough or burred tonehole rims.

'Operator' ( that's you, the player! ) factors that contribute towards sticky pads are eating, drinking, smoking...and breathing. Pick three out of that list and try not to do them before playing. A non-existent bore-swabbing routine doesn't help matters - though ironically enough there are times when it can actually worsen the problem! See the Lab Test pages for further details.

There are quite a few products on the market that claim to be able to cure or prevent pads from sticking. The most common and widely available are the powders. Essentially these are little more than talc, the theory being that they absorb the gunk that collects on the pad and provide a means of dry lubrication. The truth of the matter is they make a hell of a mess and eventually exacerbate the problem. All you're really doing is adding yet more gunk to the surface of the pad - and once you start using the stuff you find you have to keep using it to cure the stickiness that the talc contributes towards!

Another popular solution is called pad dope. Typically these are oils - such as neatsfoot. The claim here is that these products are supposed to waterproof the pad, the theory being that if you can stop the water from being absorbed by the pad then it won't stick. The problem is the oil itself can contribute to the stickiness, and the goo present in the condensation can still deposit itself on the pad whether it's waterproof or not.

Such treatments are analogous to spilling a glass of beer on your kitchen floor and cleaning it up by throwing powder or oil on it, and hoping it goes away.

The outlook then is bleak.
But there are one or two tricks that can help.

Cleaning and degreasing the pad is an effective solution. There are no magic ingredients and potions involved - just plain old ordinary lighter fluid - and common or garden cotton buds ( American readers will know these as "Q-Tips" ).
The method itself is simple too - wet the cotton bud with lighter fluid and gently rub it over the pad, concentrating your efforts on and around the impression made by the tone hole.
I should point out that by 'lighter fluid' I mean the stuff used for filling petrol cigarette lighters, like the well-known Zippo ( in some parts of the world lighter fluid is an entirely different spirit ). Common brands include Swan, Ronson and Zippo.
While you're there it's worth giving the tone hole itself a bit of a wipe over, particular the bore of the hole as this often harbours dried goo which dissolves when wet and finds its way onto the pad again.

If you find a cotton bud a bit of a tight fit, use a pipe cleaner - though bend it in half first so as not to risk the wire core puncturing the pad. You may have to make a couple of applications if the pad is particularly gummed up - and if it's that bad then maybe it really IS time to have it replaced!

For flutes and clarinets you can use a piece of cotton cloth, a corner of which you moisten with lighter fluid. Place this corner under the pad and very gently close the key onto the cloth. Slowly and gently drag the cloth out.
It's worth pointing out that this method can shorten the life of a skin pad - so you might well find it enough to merely press the key down onto the moistened cloth and leave it at that.

Sax pads often suffer from an excess of dried saliva deposits, and you might well find that a cottonbud soaked in a little saliva will be the best cleaning method. Follow it up with the lighter fluid though.
If the tonehole rim or its corresponding impression in the pad looks a little green then it's a given that you have verdigris contamination ( verdigris is a form of corrosion that attacks brass and other copper-based metals ). In such cases it might not be enough to clean the pad and tonehole with a solvent, you might need to resort to a mechanical method.
Traditionally this involves slipping a dollar bill over the tone hole, pressing the key cup lightly down and pulling the bill out. In effect the dollar acts as a fine abrader ( apparently there's a particularly quality to the paper - but I suspect most paper currency would work ).

Some people advocate the use of Crocus paper, which is an extremely fine grade of carborundum paper.

These methods work, but are best used sparingly because of the associated risks of damaging the pad. In any event, following up with lighter fluid is a good bet for a 'belt and braces' approach.

I've often seen comments to the effect that lighter fluid will harm the pads, the reason given that it "dries out the leather's natural oils". This is easy enough to test, and in my workshop sits the skin of a used pad which has been subjected to at least a weekly sloosh of lighter fluid for the last couple of years. That's a very great deal more lighter fluid than you'll be likely to apply to a pad in its lifetime - and yet the leather shows no sign of disintegrating.

I feel duty bound to point out that lighter fluid is highly flammable - so please bear that in mind if you decide it would be a neat idea to ungunk your pads before a blazing log fire. Lighter fluid is also a deeply dangerous and unpleasant drink.