Ah, ok, makes sense.

As for major sources of Mercury CA, not sure. My LHS gets it, but I know you said you were a good ways away from an LHS. Might try their "Where to buy" page at http://mercuryadhesives.com/dealers.asp

As for your other bottles going off, and the comments about not being able to get the cap on, etc...that's PRECISELY why I switched to Mercury.

Without getting into to much detail (As I said...their science page does a much better job than i could) :

1) Most of what you're seeing with CA bottles hardening is simply the CA going off, or curing. Moisture is what activates CA, and all the other major manufactures have huge drums shipped overseas. This means by the time you get your Tower of GP CA, it's been on a boat, in the sea air, and then in a warehouse, and then bottled, and then shipped to your store, and then to you. It's no wonder the stuff goes off soon after we get it...the wonder is that it hasn't already!

Mercury, on the other hand, is made in the states, as needed, and thus quite fresher and newer when you get it...and it hasn't spent months in the moist air of a sea journey.

2) Their bottles are quite well designed. The cap has a ROUNDED pin to keep the tip clear, but not scratch it up 9which leaves grooves for CA to cure), and the silicone tip resists CA bonding on it.

What i've found is that even the most basic of attention (just wipe the threads with a paper towel when done, for example) will keep a Mercury bottle clean, usable, and easily opened for a YEAR or more.

I've also found that it being fresher means it's more predictable and reliable. Its work time is consistent from bottle to bottle, the bonds strong and reliable, etc.

All in all, given that it's no pricier than any other CA, you really can't beat it, imo.