How can we simulate UV damage on materials for an experiment?

September 14, 2018 12:53 PM

Should we just get large lights?

We want to see if a new type of flooring material will not get the uv damage other types of flooring get when constantly exposed to sun. We could put it under sunlight, but it would have to be outside for months for our purposes. Is there a way to speed up the process so that we know much sooner? If lamps are the answer, what kind of lamps do we need? any help would be appreciated.

posted by fantasticness to Science & Nature (6 answers total)

There are standard ultraviolet (and sometimes moisture) exposure tests for just this reason. Look at ISO 4892 for example, and there’s probably a similar ASTM spec. They will define what kind of lamps to get. Alternately, a test lab may already have a chamber you could rent.

One test duration I see for a specific application is 700 hours, which is about a month. Still a long time, but not like years long.
posted by Huffy Puffy at 1:18 PM on September 14, 2018 [4 favorites]

ASTM has standards on this sort of thing, which may be useful even if you don't intend to formally certify a given level of UV resistance. Look at ASTM G-154 (and maybe G-155, and possibly others I'm not aware of). G-154 uses fluorescent sources, while G-155 uses a xenon arc source so if you want to replicate these at home, G-154 will probably be easier although G-155 is generally considered to be more accurate regarding color fading etc (G-154 is fine for mechanical properties in most cases).

...both of these approaches will tend to fade any object that's exposed to the light (although the actual target will of course be most affected) so if you're trying something at home you'll almost certainly want to build a protective box to enclose them.
posted by aramaic at 1:18 PM on September 14, 2018 [2 favorites]

"Accelerated UV" testing is a thing, and a good google phrase.

A (american) standard to reference is ASTM G154

You'll probably want to look into contracting this work out though, due to the expense of the lamps if you're not going to be doing this all the time.
posted by ArgentCorvid at 1:20 PM on September 14, 2018 [1 favorite]

Any UV lightbulb of the kind meant for sterilizing the environment is giving off the more energetic, and therefore hazardous, UV-B bands of light. They are sold as "germicidal" UV Bulbs, so that's your search term.

A short term exposure to these bulbs is not going to hurt you, but it's not good for you, and it just takes a couple random photos to kick your skin cells into a cancerous rampage, so make sure you can turn off the lamp before entering the test area; use eye protection anyway. The bulb should also be naked, i.e. not behind a sheet of glass which would render them useless.
posted by Sunburnt at 4:13 PM on September 14, 2018 [1 favorite]

I've actually done this testing, using UV lights to simulate sun exposure on epoxy flooring. We were not the kind of lab that had standards or procedures, so I bought a UV light and mounted it up on a stand and then put a big cardboard box over it. We had problems with people lifting the box to "see" the light, because they thought it was cool or they wanted to get tan or some such stupidity.
My findings: 1) Epoxy doesn't do well with UV, 2) there is no simple correlation between amount of time spent under a light and amount of time spent outside, but you can see that some things are relatively better than others and 3) putting a sign that says "Do not open this box, cancer inside" on a box doesn't stop everyone from opening a box.
posted by Vatnesine at 5:14 PM on September 14, 2018 [5 favorites]

Germicidal lights typically produce UV-C (100-280 nm) as well as UV-B (280-315 nm) -- in fact the linked light produces 95% of its light at 254 nm -- and the 184 nm UV-C emission peak of mercury vapor produces ozone, while the 254 nm peak dissociates that ozone into oxygen and the even more reactive than ozone singlet oxygen, so if you use a germicidal light especially in a sealed container, you're subjecting your samples to ozone and atomic oxygen as well as UV.

And not only that, sunlight contains very little UV-C, and the UV-B component of sunlight is only ~5% of the total, with UV-A making up the other 95%.

Which means you might well get a false positive from using germicidal lights -- that your flooring is indeed damaged by UV -- but if your flooring comes through, you could be pretty confident in that result.
posted by jamjam at 9:31 PM on September 14, 2018 [1 favorite]