I had tin gutters — actually terne, a zinc/tin alloy — on my turn-of-the-20th-century former house. The experts recommended Tin-O-Lin, which I bought at a Philadelphia roofing supplier, a slow-drying linseed oil-based primer and finish coat recommended for spot priming exposed and rusted areas.
It was not recommended for anything but roof applications. When I checked recently to see if the recommendations had changed, they had not.
I would assume that the same instructions for painting aluminum would apply to tin, and I am referring to the procedures established by the Dow Paint Quality Institute in Spring House.
Treat any mildew with a 3-to-1 mixture of water to household bleach, leaving it on for 20 minutes and adding more as it dries; wear eye and skin protection. Rinse thoroughly.
If there is any white oxide on bare metal, remove as much as possible by rubbing with nonmetallic scouring pad. (If steel wool is used, residual particles, if not completely removed, can eat pin holes through the aluminum.)
Remove dirt, chalk, treated mildew, etc., by scrubbing with detergent and water, and rinse thoroughly; or, power wash with plain water. Chalking on weathered aluminum siding tends to be deep in the factory finish, and a second treatment may be necessary.
Priming the old factory finish generally is not necessary if chalk can be removed as part of surface preparation.
For areas where chalk is stubborn and cannot all be removed, apply a solvent-based exterior primer recommended for this substrate.
For areas where metal is exposed, remove any white powdery oxide with a nonmetallic scouring pad, and apply a latex or oil-based exterior metal primer that is recommended for bare aluminum. Do not leave a primer unpainted.
Use top-of-the-line, exterior 100 percent acrylic latex house paint in flat or satin finish, depending on appearance desired. A flat finish will be much less revealing of dents and irregularities in the siding than will a glossier finish.
For best results, apply by spray.
I don’t know the extent to which your house has been insulated, since it was built in 1950, but if you choose to replace the tin with vinyl, you might want to tighten it up.
As regulars know, I try to make this column as participatory as possible, presenting others’ opinions to foster dialogue.
I knew running a few bits of microbiologist Myron Wentz’s new book a few weeks ago would generate comment, and reader Sam Goldwasser offered some.
“Some of [Wentz’s] recommendations are either based on a flawed understanding of technology, or are simply unrealistic,” Goldwasser wrote.
Here’s one: “Modern compact fluorescent lamps have a very minuscule amount of mercury and it doesn’t leak out while they are being used, only if broken. And to suggest switching back to incandescent lamps is nutty. Incandescents are not only energy hogs (about four times the energy of a compact fluorescent lamp with similar light output), but the greater energy consumption means using more coal-fired power plants, and these end up producing mercury emissions.”
And one more: “Electromagnetic fields from high-voltage power lines are much greater than from most appliances, despite the appliances being much closer,” he said, explaining there is very little chance of anything dangerous leaking out of your toaster or washing machine.
“The suggestion to unplug is simply unrealistic for many modern appliances. Especially if electronics like audiovisual equipment are considered, as they may lose all their programming. And my electric stove doesn’t even have a plug!”
Questions? E-mail Alan J. Heavens at firstname.lastname@example.org or write him at The Inquirer, Box 8263, Philadelphia 19101. Volume prohibits individual replies.