What is the shelf life of common adhesives?

[Tim R]

On Friday, January 26, 2018 at 12:39:19 PM UTC-5, et...@whidbey.com wrote:

I don't know about the shelf life but I do know about bonding metals
with epoxies. Aluminum can be especially hard to get a good bond on
because of the oxide coat. But this problem is fairly easily overcome.
Apply the epoxy to a clean oil and grease free surface. Then use a
small stainless wire brush to scrub the epoxy covered surface. Using
this method keeps oxygen away from the aluminum during the scrubbing
and the scrubbing action removes the super thin oxide coat. The
particles of aluminum oxide just get mixed into the epoxy. The epoxy
will wet the now oxide free aluminum surface. This process also works
when trying to solder aluminum. I have had to prove to a couple people
while they watched that this method works.
Eric

About ten years ago I repaired a broken solder joint on a small bracket, between two pieces of brass. This part is used every day and gets a fair amount of mechanical force applied. I used JBWeld but I was scrupulous about removing all the solder and getting down to bright clean metal on both pieces. So far it is holding. I also wired it in place until completely set.

 

On Saturday, January 27, 2018 at 5:47:27 PM UTC-5, pf...@aol.com wrote:

Let's cut to the chase:

a) Shelf-Life is not uniform. Factors such as heat, humidity, temperature cycling, even altitude and more must be included in the process.
b) The nature of the adhesives are factor.
c) That some components will separate into separate ingredients depending on temperature is a factor.
d) That some cures are catalytic is a factor - and that once started, will continue until complete.
e) That some cures require exterior stimulus is a factor.
f) And some low-end epoxies will crystallize, one part especially, even when fresh with a single exposure to low temperatures.

During the summer, my hobby room will undergo pretty wild temperature swings.

That sounds almost like the direct opposite of a wine cellar, which is kept at a certain temperature year-round for years. Even decades.