Organic materials such as plastics, inks and coatings are usually damaged by exposure to light and weathering. This is the primary reason why accelerated weathering and light stability testers are widely used for material certification, quality control and also for research and development. The results produced by these testers are usually reproducible and fast. The xenon arc test chamber and the fluorescent UV (QUV) accelerated weathering tester are some of the most commonly used accelerated weathering testers. But despite being the most frequently used testers they are based on approaches which are different.
The xenon test chamber is designed in a way that it reproduces the entire spectrum of sunlight including Infrared (IR), ultraviolet (UV) and visible light. The xenon arc is basically an attempt to reproduce sunlight from 295 nm- 800nm. When it comes to QUV it just reproduces the damaging effects of sunlight which occurs from 300 nm -400 nm. This particular tester is based on the concept that the durable materials which are exposed outdoors experience the most weathering damage from the short-wave UV.
QUV Weathering Tester
The design of this tester is in a way that it reproduces the damaging effects which are usually caused by sunlight on durable materials through utilizing fluorescent UV lamps. The coating on the glass tubes is designed carefully in a way that the tubes mainly produce UV rather than IF or visible light. There are various types of lamps
that have different spectra for various exposure applications. UVA -340 lamps are the ones that provide the best available simulation of sunlight in the important short-wave UV region. The UV-B lamps are also regularly used in this tester where they cause faster degradation than the UV-A lamps.
The main benefit of using QUV is that it allows the most realistic simulation of outdoor moisture attack for it uses a condensation mechanism that is unique to reproduce the outdoor moisture. This is the most widely used weathering tester in the universe for it stimulates the damaging effects of dew, rain and sunlight.
Xenon Test Chamber
The fact that the xenon arc testers produce energy in the visible, infrared and UV regions makes them be regarded as the best simulation of full-spectrum sunlight. It is necessary to filter the xenon arc spectrum so that natural sunlight can be simulated. These filters play the role of reducing unwanted radiation or/and heat. There are different types of different glass filters that have the ability to achieve different spectra. The main factors that determine the filters that are used include the material tested and the end use application. The different types of filters allow varying amounts of short-wave UV and this can affect the type and speed of degradation significantly.
Majority of the xenon arc testers usually simulate the effects of moisture through humidity control and/or water spray systems. The xenon chambers spray water onto the test specimens so as to simulate the effects of outdoor moisture. This particular method is especially ideal for simulating the effects of mechanical erosion or thermal shock. These testers usually have systems that control relative humidity, temperature and light intensity (irradiance).
Which is better?
Making a decision on the most suitable method you use should depend on the material you are testing, your budgetary restrictions and the end-use application. This is mainly because both these approaches can be effective depending on your application.