How Long Will A Mylar Mirror Last?

May 20, 2006 10:38 AM

Under indoor conditions, what is the life expectancy of metalized Mylar?

The Mylar itself looks like it should be good for decades under the right circumstances. When they metalize the Mylar to get that reflective finish they put it through a variety of processes. I am having trouble getting a life expectancy for the mirror finish.

It will be used indoors as a reflectors in four foot flourescent light fixtures. Humidity should range from zero to one hundred percent, depending on the season. It will never receive direct sunlight, mechanical flexing, or serious vibration. Their should be no corrosive gases or abrasive dusts present. Temperatures should always stay in the sixty to ninety degree fahrenheit range. When the fixtures are operating some parts get warm, but not too warm to hold your hand against. I am aware that the finish is mechanically delicate and that people changing bulbs may scratch it.

The current fixtures are about 40 years old, and I would like to install reflectors that have a fair chance of lasting another 40 years or more. Traditional glass mirrors would cause trouble if the glue failed and they fell on the bulbs. Plexiglass mirrors are around nine dollars per square foot, a bit much for the project. I am aware that the finish is conductive and is being installed inside an electrically active unit.

posted by Ken McE to Technology (4 answers total)

I don't have an answer for you, but I wonder if you're talking about Mylar or metalized nylon? From the wikipedia entry on PET film: "Metallized nylon (or 'foil') balloons used for floral arrangements and parties are often mistakenly called 'Mylar'..."

You could try asking the AMPEF (also from the wikipedia article.)

Have you considered glass mirrors with mechanical fasteners? "Chrome" spray paint? What kind of reflectors are you replacing?
posted by hydrophonic at 12:29 PM on May 20, 2006

I used a sheet of aluminized mylar as a window blind for about five years - the only damage to it seemed to be from abrasions that scraped away some of the metal. Under your conditions where it isn't rubbing against anything I think it will be very long. In my experience, minor contact such as that from changing a bulb will not abrade it.

I don't know if it will last 40 years, but it could well.
posted by pombe at 12:57 PM on May 20, 2006

Are you talking about this stuff, which is also known as "superinsulation" and "space blanket"? It is mylar. I have heard that space blankets can degrade in storage, but the ones I made from superinsulation have been fine years later.
posted by Kirth Gerson at 7:13 PM on May 20, 2006

How much do you need? I have a piece of quite heavy duty mirror-ish Mylar-or-whatever. Way heavier gauge than space blanket or ballon, @ 2' x 4'. It was used as a mirror in a retail display and it was too nifty to throw out. It's been rolled up in a tube for probably 25 years, and has not deteriorated.
posted by theora55 at 6:06 AM on May 21, 2006