John K Jordan
The viscosity depends on the use. I keep thin, medium, and gap-filling and use thin the most. I occasionally use the flexible black CA.
I am certainly no expert on CA, all I know is what I've been told and what I've experienced.
As for brands I like Hotstuff and Mercury Adhesives, Stick-Fast seems OK. I had trouble once with E-Z Bond. I've never tried Starbond. I use the thin Parsons Parfix 3408 sometimes for finishes since it has no fumes and a 40 second cure time.
Parsons Adhesives say in general the shelf life of CA is about 1 year, longer if refrigerated or frozen in the unopened bottle. That shelf life includes the time spent in the dealer's warehouse. They also told me there are only 3 makers of CA in the US so some of brands we buy are coming from the same vats.
In my experience the glue will continue to work until it eventually thickens up and won't come out of the bottle. It can harden completely in the bottle. Apparently one enemy of CA is moisture which can actually come into the bottle through the plastic. Mercury Adhesives told me they carefully researched and tested plastics for a formulation that would keep out moisture.
The Mercury Adhesives CA glues may be more expensive but they have some benefits besides the bottle claim: the cap seals well and has a stainless steel pin that keeps the nozzle clean.
Mercury is the only CA maker I know who has a lifetime warranty on their glues. If the glue sets up in the bottle they will replace it for no charge, no questions asked.
My experience with CA: I keep it in the fridge until opened. After opening some recommend not refrigerating since unless brought to room temperature before using moisture in the air can condense inside the bottle. I have not experienced that - for years I kept it cold, used it, and put it back. The bottles deteriorated before the glue did. I currently leave a bottle of Hotstuff thin on the shelf above the lathe, uncapped but with a capillary tip. It's been there for well over a year and the glue still works as expected although the plastic in the bottle is getting stiff. I keep that bottle handy since I use it frequently. The capillary tips are perfect for putting a single tiny drop exactly where needed.
To keep the moisture out of CA glues I keep the rest of my CA glue bottles in a sealed container with desiccant beads to suck up any moisture in the air. I use the blue indicator desiccant which changes to a pink color when it's time to "recharge" it in the oven.
This is my earlier container. I now use a larger one with a lid with a clamp that is easier to open.