How should I store super glue to prevent it from drying out?
It seems like every time I open a tube of super/Krazy/cyanoacrylate glue, I get one use out of it, and the next time I go to use it months later, the nozzle is clogged with dry glue (or worse, the entire tube has hardened. I put it back into its sealed canister, but it doesn't seem to matter.
What's the best way to store super glue to increase its longevity in the tube? Does it matter if I store the tube nozzle down, nozzle up, or nozzle sideways? Should I let it sit with the pin in or not? (I assume not, or at least not all the way in; otherwise if the glue dries up around the pin, the pin won't be long enough to puncture the dried glue around it.) Should I glue something to the tip of the tube to try to seal it?
The component "super glue" is made of is cyanoacrylate which polymerizes in the presence of water. This actually is the opposite of drying out. The humidity of air already brings a sufficient amount of water for cyanoacrylate to polymerize.
Therefore the best place to store it is a dry to very dry place:
This could be a refrigerator or even a freezer. To avoid condensation on taking it out of the fridge or freezer (freezing will delay or even stop polymerization) we need to pack it in an air-tight container, envelope or bag and let it reach room temperature before we open the package.
To further make the stroage environment dry we can add a silicate bag or salt to the storage container (e.g. from the manufacturer's package of an electronic device).
Another possibility to prevent humidity to enter the opened package is storing in a vacuum sealed bag (as it may be used for food packaging).
When using and before closing we may also take care to not let humidity or air come into the tube to prevent polymerization at the outlet (commented by user 2619).
Cyanoacrylate is very harmful when ingested. When storing in a fridge or a freezer keep it away from food, use an extra box, and most importantly make sure your children keep away from the fridge.
If it's so toxic, does that mean it shouldn't be used to seal cuts on the skin? (Edit: Never mind, I see that the wikipedia page has "Skin injuries" and "Toxicity" sections.)
Given that air is humid, it's probably a good #4 bullet to squeeze the excess air out of a tube before closing it.
This is certainly a very complete answer and I give you the +1 but it seems like overkill. I don't want to worry about bagging *and* boxing my glue with silica gel and in the freezer and *then* having to let it thaw before I can use it. I just squeeze out all the air I can - until it's almost coming out the tip - and then put the cap on tight. It's what Gorilla Glue suggests and it's always worked for my purposes.