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I have a can of cortec that just passed it's 2 year shelf life. I am wondering if folks have experience with the end of shelf life or beyond cortec
I'm always skeptical of what expiry dates actually mean.
Cortec has a lab for testing the quality and durability of its products. I found this newsletter that said they tested some Cortec film that was 6 years old (presumably 4 yrs post shelf life ... I "think" all the Cortec products have a 2 year shelf life?) and found that it was perfectly OK and protective.
I realize this is an apples-and-oranges comparison (film vs liquid), but it at least sounds reassuring - for whatever that's worth! Ha! Obviously, it's easy for me to say since my build was completed 6+ years ago, but if the Cortec wasn't much beyond the shelf life, well-sealed, and had it's normal, thick consistency without separation into layers, etc., I'd probably use it!
I bought a partially-completed kit and I suspect the Zenith-supplied Cortec that came with the deal was at least 2 years old. As I understand it, Zenith buys it in industrial quantities and repackages it in quarts to make it practical and affordable for the homebuilder. My quart was clearly labelled "2 Year Shelf Life," but it had no date of manufacture or expiry! That Cortec is now probably 8 years old, at least. Out of curiosity, today I opened the can and it looks to be exactly of the consistency, odor, and color as it was years ago! Would I use it on a new build? No, it's well-beyond its shelf life, but if it were a few months past expiry or maybe a year or two, I probably would unless Zenith told me not to! You might contact them and see what they say, but I suspect they'll say, "Two year shelf life."
Mine is from 2009 and I recently coated a scrap piece of 6061t6, thinned it with distilled water, it cured normally and passed my duct tape pull test after sitting for a few days (don't forget to scuff your aluminum with scotchbrite). I plan to use it to do some touch up work on my project. The can has been stored in my basement in nearly ideal conditions, it's always about 68F. Your results may vary, good luck!