Interesting idea - I only have 2 concerns 1) won't the metal cover corrode and react with the chemistry. 2) Once those jars are opened for the first time and the button pops up, I'm not sure they're still air tight.
As somebody who re-uses glass jars with metal lids, I can comment from personal experience:
The lids do tend to corrode when used with certain chemicals -- mainly acids, in my experience. Stop bath and fixers tend to cause this; developers don't. The corrosion doesn't eat away the lids immediately, though; they last for many months (probably a year or two). The lids can, of course, be replaced with newer lids before the corrosion becomes a problem.
Opening the jar doesn't prevent the seal from being air-tight once you re-seal the jar. The seal is air-tight because air won't penetrate the jar's plastic or glass material, the metal lid, or the rubber(-like?) material that forms a gasket between the jar's lip and the lid. Merely opening the jar doesn't damage any of these components, although of course you've got to close the lid tightly to have the gasket do it's job, and if the jar or the lid is physically damaged it might not be airtight any longer.
Of course, when you put chemicals into a container and seal the lid, you'll also seal in whatever air lies between the chemicals and the lid. Factory-sealed jars are usually packed in a vacuum or in a chamber with some inert gases. You can extend the life of your own chemicals by using similar principles, although on a smaller scale. Many people squirt inert gases of various types into their jars before sealing them. My own approach is to use a
Pump-n-Seal, which creates a partial vacuum in an already-sealed jar. A similar product I've heard of other photographers using is the
Vacu-Vin. The key difference between these two products is that the Pump-n-Seal uses the original metal lids of jars; you punch a small hole in the lid with a pin and seal that hole with a special tab that enables the pump to suck out the air. The Vacu-Vin is designed for use with wine bottles and uses special caps that you must purchase. This makes the Vacu-Vin suitable for bottles of a certain shape (with narrow necks), whereas the Pump-n-Seal is useful with a wider variety of jars. The Vacu-Vin's caps are also more expensive than the Pump-n-Seal's tabs. I don't know which device creates a better vacuum. (I'm sure neither one is anywhere close to a true vacuum, though.) When I open a jar that's been sealed with a Pump-n-Seal, even if it's been sealed shut for weeks, I hear the same sort of "schlurp" sound I hear when opening a factory-sealed jar, and the dimple in the lid pops up, indicating that the seal was indeed airtight enough to maintain that partial vacuum since I sealed the jar.
