You've all seen those old churches and buildings with copper roofing. With age, it turns green. Well, when bronze ages it first turns to a nice patina and then, dues to the high copper content, green.
I decided to seal all twelve portlights before departing across the ocean this summer. To do this, I have to remove each portlight from the boat; remove all old sealant residue from both the boat and the portlight. After that, the portlight will be re-installed and sealed; making a watertight seal.
As you can see from the photo below, the portlights are corroded and the glass is starting to delaminate. I decided to take advantage of this opportunity to cleanup the portlights. Besides removing the old sealant, I was going to polish the bronze. The plan was not to polish them to a bright mirror-like finish, but to make them shiny and clean... and definitely not green. There is no stopping the bronze from corroding at sea. So, my plan is to allow them to oxidize; that protects the metal. Then they can turn a nice bronze patina. I'll keep them clean enough as to not turn green again.
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| Portlight, removed from the boat |
I checked around Syracuse with several of the glass companies about having custom made glass. You can see in the photo above, the old glass is starting to delaminate around the edges. Solvay Glass was the most helpful. One look, and they knew exactly what kind of glass. That put them ahead of all other companies. The said they could make the new glass fit a little better than the original glass did if I would leave the frame with them. So, of course, I did.
This meant a lot more cleaning because the windows had to be disassembled, the glass removed and the window frames cleaned with all sealant residue removed. As you would expect from a boat, the window seal was completely different from the portlight to boat seal.
I contacted 3M and they were helpful as far selecting the right sealant for the glass. However, their help ended there. Another company Sika was far more helpful. They explained that glass is not a porous material and does not accept sealants well. So, for the boat, they recommended a chemical activator to pre-treat the glass, which was made specifically for my purposes... it's how the windows on cruise ships are sealed. Then I would need a primer for the bronze because that was a very porous material. They explained the exact process and timing of the applications for the bronze primer, glass activator and sealant. They also told me exactly which sealant to use with bronze frames.
At first this all sounded very complicated, but in practice it was simple.
The picture below is the finished work on one of the portlights; polished and new glass installed.
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| Polished Portlight |
