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Desoldering technique

What is the technique for using these needles then? You heat the joint with an iron and then push the needle over it quickly?
 
That's it. Very useful for clearing a solder-plugged via or one with a bit of a pin stuck in it.

An unrelated application is that I've found these to be useful for straightening bent pins on those fine-pitch USB3 motherboard connectors. You can usually find a needle that exactly matches the pin size.
 
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All the above are very good to excellent suggestions. Good quality wick is a blessing and I've settled on Superwick vs. any other brand. There might be others or even better brands, but the eBay cheap stuff is nearly useless for most jobs.

One idea I didn't see above is to preheat a multi-layer board to help with removing solder from pins passing through heavy ground planes. An iron just can't apply enough heat to melt solder if there's a large heat sink. I have a preheater hot plate plus I have just used my hot air station to warm up boards. Just don't melt anything plastic or cause SMD components to fall off boards with too much heat
 
One idea I didn't see above is to preheat a multi-layer board to help with removing solder from pins passing through heavy ground planes.
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You just beat me to it - I don't have a hot plate for uniformly warming the PCB with but if you have a hot-air wand of the sort that you would typically use for SMD rework, toasting the underside of a double sided PCB in a good radius around the work area makes it a lot easier for your desoldering tool to do its work, otherwise much of the heat being produced by the desoldering iron tip gets drained away into the surrounding cold area, forcing you to keep the tip applied to the pin and pad for longer and potentially burn the pad off the PCB. I warm the underside up so it is too hot to touch, but not hot enough (by itself) to melt the solder on the pins and certainly not hot enough to brown or burn the PCB itself.

As has been said above, liberally top up any joints to be desoldered with lead / tin solder first and if your first attempt does not free the pin completely don't persist in trying to desolder the 10% which is left - top the joint back up 100% with fresh solder and have another go to clear it completely in one go.

Never, ever, try to lever an almost desoldered DIP IC vertically upwards off a double sided PCB by inserting the end of a screwdriver underneath - the chip will come off all right, but there is a high chance some of the top side pads and tracks will come off with it. Apart from anything else, hoking a screwdriver around underneath the end of an IC also runs a high risk of gouging through copper tracks which run underneath the IC on the top side of the PCB.

Instead, push the IC firmly from side to side, back and forth, bending its pins from side to side a little, ideally with something like the flat end of the wooden handle of a wire brush, so that if it skids off and rakes across the PCB, it won't do any damage to the PCB top side. Do that until the remaining solder cracks - you will then be able to just lift the IC out with your fingers.
 
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