The XTC is a better match with sunlight in the long-wave UV and visible spectrum

Long-wave UV and even visible light can cause fade and color change in pigments and dyes. Where color change is the issue, the XTC is usually recommended. The XTC, using Window Glass filters, is also generally better than the XTC for testing indoor products.

The UV-3 is better at simulating the effects of outdoor moisture

The UV-3’s condensation system (100% RH) is more aggressive and realistic than the XTC’s water spray and humidity control systems. Deeply penetrating moisture may cause damage such as blistering in paints.

The XTC is better for controlling humidity

The XTC can control relative humidity. This can be an important feature for humidity sensitive materials like many textiles and inks. High humidity can cause color shift and uneven dye concentrations.

A Two Tier Approach

Because many researchers are concerned with polymer degradation, moisture degradation and color change, a two-tier testing program is often the best approach. Many manufacturers get cost-effective results by using the UV-3 Accelerated Weathering Tester for polymer degradation and a XTC Xenon Test Chamber for color change.