Inland now, but lived on the Atlantic for years - solid brass, bronze, copper (not plated, but entirely that metal). Of these, brass is the least expensive & most traditional, used for centuries on coastal properties & boats. Best without a clear finish coat (usually lacquer) as that will quickly crack & discolor, requiring removal to polish. All will form a surface discoloration - patina - in a thin layer that actually protects the metal from deteriorating. First reaction is usually the pale greenish patina, which continues to darken over time to brown & then black. If you prefer a bright shine rather than patina, you'll need to clean the fixtures in place at least twice a year. Get some inexpensive Barkeeper's Friend and Bon Ami powders. Both come in shaker cardboard cans, can be found in grocery & hardware stores with cleaning supplies & do a good job without a lot of mess or elbow grease. Like to use both dry on a damp rough cloth like terry washcloths sold in multiples for cleaning. Barely dampen the cloth, just enough to allow the powder to stick to it (spritz it with water), and rub over the surface. Turn the cloth to a clean section & apply more powder as you go. Start with the Barkeeper's to clean & follow with the Bon Ami to polish after cleaning. Just shake the powder onto the cloth or shake some into a dish & dip the cloth into it. Bon Ami does a great job on any glass, too, where the Barkeepers may be too rough. For the glass, use Glass Wax after cleaning to keep it clean. There are oils & waxes for the metals to delay tarnishing, if you like. Check at marine supply shops for these. A piece of paper, cardboard or masking tape can keep the surface where the fixture fits clean during the process. Loosen the screws that hold the fixture slightly to slip these behind. If you're really thorough, remove the screws one at a time, clean with the powders & an old toothbrush & replace. A toothbrush will help with any grooved parts on the fixture, too. Same process with other exterior brass such as doorknobs. New solid brass can be pricey, but then again won't need to be replaced. Used brass fixtures are very reasonable. (Found a set of 6 large wall lights & a matching post light on Craigslist for $25 total that now grace this house after an initial cleanup.) If you're not comfortable rewiring older ones, lamp shops can do the job. Make sure to specify "exterior" wiring to hold up for damp & wet installations.

Amanda, where are you located? Not all ocean front is the same! We rented an ocean front house in Santa Monica, CA for a month and it is not the same climate as being ocean front in Florida or NJ. The overall humidity is much lower in CA and we get very little rain, so there is a lot less damage to property. I used to live in the northeast, so I'm always amazed at how long things last here in CA. You see few rusted cars. Exterior paint jobs seem to last for ever. I just had my wood stained garage doors touched up after 7 years of eastern sun exposure. They would have needed work after 2 years if I lived anywhere else.

I suppose but you need to get it glued to the wall really good. Problem is that the material probably doesn't measure a full 1/8" nor is the quarter inch stuff a full 0.25". And it will telegraph any waves in the wall more readily than the thicker material. Since you're planning to add the divides, any waviness will be less noticeable, though. May be a little difficult to find, especially the thicker stuff. If you come up empty, try calling around or dropping into sign painters' shops and ask what they use & where they get it. (They may have some on hand & be willing to part w/ it.)

Im sorry, but just because they are little known to you does not mean they are not known well with in the industry! I promise you that. You are on the east coast.. I have NEVER heard of Brass lIght Gallery in my life lol. So this might just be an east to west coast "ive never heard off, or little known," Because on the West coast they are well known.