As usual in these threads, it would be really helpful if you told us what you were doing. For example, if you’re putting two things together and you want them to fall apart or let loose on their own, that’s one thing. If you want want to be able to separate them at some later date, those Command Strips work pretty well. If you might need to reattach them again, Velcro works well too. There’s also Velcro with Command Strips on it so you Velcro as you’re used to it, but if you never need it again, you can get it off.
On the other hand, if the timing is specific, the materials you’re mounting to each other (and other environmental elements) and for how long are going to be important.
For stickers, labels, and things like that, you can loosen the glue by heating it up with a hairdryer. Caulk can be loosened with a heat gun. There are probably lots of adhesive materials like that where it keeps its strength but you can weaken it yourself at a later time.
I’ve often thought that there should be a glue based on sticky organic stuff, like oatmeal, for situations like you describe. If I leave my oatmeal spoon in the bowl, I can sometimes lift the bowl by the spoon when it dries. It seems strongest at first but doesn’t last. And it’s easily dissolved with water.
A penetrating oil or WD-40 is designed to do just that, although typically for rusted on bolts. I know you can use WD-40 to remove sticker residue. It could be that a simple adhesive could be used on the threads and then WD-40 could loosen it.
Loctite is specifically intended to stop threaded fasteners from working loose, but it doesn’t degrade over time, it’s just possible to unscrew it by applying enough force. It’s unclear to me why you’re gluing the lid on. Are you trying to stop vibration-induced loosening? Or do you want to prevent someone from deliberately unscrewing the lid? Also, are contents intended to be edible after opening? If so, that will limit the type of chemicals you’d want to apply to the lid.
Plain 'ol Elmers white glue is water soluble and will release if placed in a wet or humid environmental. Same with mucilage.
Resorbable sutures and other surgical fasteners are molded from polylactic acid and degrade over time from exposure to the body’s moisture. I imagine that an adhesive could be developed with similar chemistry.
I’m not aware of any adhesive that will spontaneously break down without external environmental influences.
Right, a little more description might help. I mean, my thought was maybe just a Mason jar with a screw-on (and screw-off) two-part lid would work. Not going to come off until you want it to, but won’t freeze in place either; and you’ve got an air-tight seal in the meantime.
As mentioned above, Loctite do a version of their thread locker designed to allow removal of a bolt. But it stays the same strength. It is simply designed to fail at a useful point. Being a cyanoacrylate it can be made brittle and this serves the purpose well. Most glues are formulated to avoid such brittleness. The usual reworkable glues are still hide glues, which need heat to loosen. Still very much the mainstay of musical instruments. I could imagine some polymers that could be convinced to depolymerise with the application of heat or maybe could include a compound that might initiate depolymerisation with some trigger. But a glue that fails after a specific interval of time is going to be difficult at best.
There are glues that will dry out over time and lose their grip but it’s not the kind of thing where you can rely on a particular time period, and certainly not just a few days. I suppose it’s possible to create such a thing using micro-encapsulated release solvent. In that case the glue itself would have to slowly dissolve the capsules, so for practical purposes the glue itself would have to be a binary compound so that process starts only when the glue is mixed for the first time. Would be easier to use a macro-mechanism that releases solvent when the designated period has expired.
Recalling an episode of the Odd Couple, I believe it was barnacle glue that Felix and Oscar tried to sell, only to find that the glue lost it’s hold when it dried. So possibly you could have a glue which loses all adhesion when one of it’s components evaporates.
My first thought here was that adhesives losing their adhesiveness over time is more of a bug than a feature. So to intentionally making an adhesive lose strong over time would be more of just not trying to make the adhesive last longer.
Masking tape has this property. A painter applies it and it will hold quite well so one could paint whatever, then the next day it’s dried out enough where it will pull right off.
I’m wondering if just applying a little bit of superglue to the outside of the container, to hold the lid to the glass is a good idea. When I want to open it again I can just dissolve it with acetone.
Also glue that doesn’t have a permanent hold is not a terrible idea. sticky notepads were an idea that came about because the glue sucked so someone figured they would be good for attaching small notes that could be easily removed.
I can think of cases in which such an adhesive would be useful – for example, if you’re doing engraving or sculpting on an object that needs to be held immobile, but has such an odd shape that it can’t be clamped down – but I don’t know of any glue that fits the bill (other than the aforementioned Spider-Man’s web or Felix & Oscar’s barnacle glue).