Water-filtered, infrared A (wIRA) is full-spectrum light filtered by a hermetically sealed water filter which filters out all the harmful ultraviolet (UV) light waves.

Only visible and the first band of infrared light, known as infrared A, is allowed to pass through the water filter.

The process is similar to the filtering of sun light by upper atmospheric moisture.

Moisture in the atmosphere filters out harmful UV and far-infrared light waves

The water filter in the hydrosun 750 emulates the effects of amospheric moisture.

Images above showing treatment of shoulder, lower back and sinusitis.

Graph above shows the light spectrum of the hydrosun 500 showing the light spectrum difference between water filtered only (blue line) and additional orange lens (orange line). The orange lens filters UV and some visible light.

Graph above shows sunlight radiation levels during a European mid-summer sunny day (blue line). The orange line is the spectrum of water filtered infrared A (wIRA). The red line is the spectrum of a 3000 K halogen lamp with an infrared lens but without a water filter from a typical LED infrared lamp. The green line shows the spectrum of a 1750 K low wattage lamp.

The graph above is the extended view of the previous graph showing infrared C light sprectrum (far-infrared). The water filter has filtered out the infra B and C spectrum.

wIRA penetrates deeper and increases the temperature in the deeper layers more effectively than conventional infrared lamps:

Thermographical comparison of skin surface temperatures in the lumbar region 12 minutes after beginning of irradiation with water-filtered infrared-A (left) and conventional infrared (right) with the same irradiance: the skin surface temperature is higher in case of irradiation with conventional infrared (presented in the thermography), while temperature in 1 cm depth of tissue is higher when irradiating with water-filtered infrared-A. So water-filtered infrared-A presents a high tissue penetration combined with a low thermal load to the skin surface.

Reference:  Gerd Hoffmann Principles and working mechanisms of water-filtered infrared-A (wIRA) GMS Krankenhhyg Interdiszip. 2007; 2(2): Doc54.