Great writeup and photos. Photos are always so great for describing exactly how to do something. Thanks!
I may need to reseal a 55 in the near future and this article will be a great help for me.
I have a few tips for using Silicone sealants.
First, as much trouble as we all go to, keeping our aquariums safe for our fish, I can't imagine using anything but a Silicone sealant that is proven safe for fish, or is made and sold for this purpose.
Amazon sells several brands of aquarium-safe Silicone sealants, as do other on-line retailers. So why not just use the stuff that's made for the job?
And, from years of using various types of Silicone sealants, I have a couple of tips:
First. Don't ever use Silicone that's expired. There should be an expiration date on the package. Believe me, if the stuff goes bad, it's a real mess to clean it off so you can then re-do the job. So don't risk it. Use fresh Silicone. As much work as this all is, why risk having it fail because you had old Silicone? Take it from me, it can and does go bad, and when it does, it fails to cure properly.
If in doubt, test some by squeezing out a good-thickness blob onto something disposable and then allowing it to cure for 24 hours. If it doesn't set up to the correct tough, rubbery consistency, then toss the tube and get some new stuff. Good, fresh Silicones cure quickly and thoroughly. Bad old Silicones take longer to cure or don't fully cure at all. Not good!!!!
Silicone sealants and adhesives cure by absorbing and reacting to atmospheric moisture. We used to force-cure Silicones by exposing them to high temperature and high humidity. They cure fast when humidity is high, and by that same token, dry conditions make them take a lot longer to cure. We were able to force-cure GE Silicone II in an hour by exposing it to 100% humidity at about 140 degrees F. I don't recommend doing this, but just keep in mind that warm humid conditions will really help it cure.
Note that I'm saying "cure" and not "dry". Silicones don't "dry". They cure. It's a chemical reaction with moisture that causes them to harden. Silicone sealants used to always be called "RTV". That stands for "room temperature vulcanizing". The idea is that the stuff goes from a semi-liquid to a hard rubber-like material. Typically, natural rubber is "vulcanized" by exposure to high temperatures. (Thus the name "Vulcan"). RTV (Silicones) are not natural rubber, of course. They just came up with that phrase to describe the way the stuff behaves to people who were familiar with vulcanization.
As time went on, I suspect GE's sales people realized that they could sell RTV to consumers, not just industrial clients. And they figured out that most consumers have no idea what vulcanization is. So they eventually dropped the RTV name and just started calling it "Silicone".
Anyhow, RTVs are great stuff.