How are paint companies e.g. testing their products for a substained amount of time succesfully? Are they really painting a house and then wait 15 years to see the result?
In: 24
They usually paint samples, then test them under wear that approximates 15 years of use. Like super intense uv and weather stuff that may only take weeks, but they can extrapolate to 15 years based on those short weeks of intense exposure.
Many of these environmental processes are simulated with accelerated frequencies.
For example many years of direct sunlight exposure can be simulated with UV lamps over a much shorter timespan like a few weeks.
Combine that with a climate controlled environment that simulates the change between the hottest of summers and the coldest of winters and you have a pretty good estimation of what happens to your product after being exposed for a few years.
Source: Some of my coworkers use those environmental chambers every day to test materials and their durability.
I believe they use salt as a corrosive agent that simulates weathering. Not only is it cheap but salt can cause a lot of wear and tear really quickly.
Sort of similar to how they test firearms by throwing them around, shooting thousands of rounds through them, and subjecting them to “sandstorm” conditions and rapid temperature changes.
Most durability tests in any field can isolate what causes aging and then try to simulate it.
So in the case of paint is probably intense UV light that simulates years of aging in a few days along with heat and cold cycles to test the paint as it stiffens.
There is basically two ways:
1. Yes, paint different materials and leave then to the elements for a specific time period.
2. Pain different materials and ‘force’ exposure and wear and tear in an intense, but shorter, period. Examples include: hard water spray to simulate years of rain, intense light and UV exposure to simulate passing days, increased abrasion to simulate wear and tear, shot but intense temperature variations to simulate seasons.
I used to work in an asphalt binder plant in the lab. We had a process and equipment that would simulate 30 years of exposure in four days. Of course the process was developed over decades and compared to long term testing to ensure the results were comparable. Given enough data-points and long enough history you can develop a short term test that will give you long term estimates.
I also worked in the research department of a polymer plant. One test of how our product performed after seasonal variations was we put them in a semi reefer (refrigerated) trailer. We’d cool them down a week until they froze, then turned off the unit, open the doors and let them acclimate to Deep South summer. Repeat for a few months and you’ve simulated years of seasonal temperature changes.
There is a group of tests know as “accelerated aging tests” – the general idea is you figure out what causes degradation of your product and expose it to those factors as much as you can, as fast as you can in a controlled manner.
If UV is the key risk, then expose it to high amounts of UV light, if salt water is your problem then you can use a concentrated solution. If it’s abrasion, then you can blast it with abrasive substances. For hot and cold or pressure, often the number of cycles is more important than the duration of exposure so you might transition from a simulated “hot summer” to a “cold winter” lots of time in a short period of time or pressure cycle a pressure tank repeatedly until it cracks (e.g. presurised aircraft fuselages are generally rated for a number of take-offs and landings rather than or in addition to the number of flying hours as that pressure cycling is the key factor).
I’m simplifying a fair bit here on the examples for simplicity and because doing these tests isn’t my field of expertise but it should give you the idea.
As others have said, accelerated aging with temperature, humidity and uv exposure is done for a quick(er) feel for how things will hold up.
But I worked for a company that made paint binders, and we had a huge field with racks of painted samples – wooden boards, metal panels, etc, all just sitting exposed to the weather. Some of the samples were 20 years old. When folks retired, they briefed a younger chemist on what they had on exposure.
When i worked in R&D at a paint company they tested using several methods. The most natural test was painting several samples on various materials and leaving them outside facing south with a 45° angle. This was done in many locations in the country and those samples were studied over time.
Some of that, yes. It’s not unheard of in science to store samples for many decades. I’ve worked with samples from as early as the 1950’s.
Those tests are long and difficult, though. They are often supplemented by “accelerated weathering” tests. The exact role of the paint changes what these look like. They probably involve sunlight and water, possibly salt, maybe heat, intentionally scuffing the paint, electronic testing, striking the paint with a calibrated hammer, or any host of other things that may simulate real-world conditions taken to the extreme.
By comparing the results of long-term tests and accelerated tests of the same paint, you can make predictions about new paints based solely on the short-term results.
In almost all cases, no testing is needed because the pigments used now aren’t new, they’ve been around for decades, if not longer. So the amount they fade with time can be seen in real time.
UV-resistant additives or coatings still need testing though, so there’s that. In which case intense UV exposure that simulates years of sun is sufficient to pretty closely approximate real-world conditions.
Latest Answers