Never, ever work with expired silicone caulk. That is what I learned.

Even though it was unopened, the expired tube had started to congeal and refused to be compressed when loaded into the caulking gun. I even went so far as to grab a set of vice grips, which I used in an attempt to get enough pressure on the trigger to do something. Unfortunately, all I managed to do was bend the trigger mechanism completely out of shape. The only way I was able to get any silicone out of the tube was by scraping it out with a pair of sticks, then applying it with a popsicle stick. One thing that I noticed with my extraction method is that it was aerating the silicone and there were tiny bubbles in the sealant as it was coming out, and my gut told me that it was going to give me problems later. (and made a note to order myself a fresh tube when I was finished)

As the tube indicated a 24 hour set time, I figured I’d have had an update to post by Tuesday (Wednesday at the latest) regarding the irrigaton lines and window box repairs, but the silicone wouldn’t dry. It remained wet/tacky for 6 days under the direct airflow of both my ceiling fan and a floor fan that I set up nearby in an attempt to move air across both sides of the silicone simultaneously. (I’m glad I had the foresight to order a fresh tube Sunday afternoon, when I was finished applying what I had)

Even though they were still tacky on Thursday, I thought I’d test the seal on my repair job and fill the two troughs with water, and leave them in my bathtub for 24 hours and see if they were able to hold water.

While the neither of the 2 boxes/troughs leaked the silicone had a somewhat crumbly texture and I didn’t trust it. I think that is courtesy of the aeration, more than the age of the sealant.
I noticed similar crumbly texture out of the seal/plug I made for the irrigation lines and pump. In this case though, it actually started falling apart when I tried inserting the lines into the pump.

I’m glad I ordered the fresh tube of caulk. its due to arrive by Wed.
In hindsight, I realize that I could have saved myself a headache when fabricating, and just cut the tube in half and scooped the silicone out that way