## WHAT DEFINES THE QUALITY OF A FILTER IN A WELDING HELMET?

How important is the optical class?

The EN 379 standard defines 4 fundamental criteria for the optical quality of a welding filter. It allows quality levels to be measured and compared based on the welder’s needs. For LCD filter models, the optical class clearly indicates 4 criteria according to the optical characteristics, rated from 1 (excellent) to 3 (good or satisfactory).

OPTICAL CRITERION 1.  Evaluates the filter surface, which must be completely flat. All filters with CX10 technology are classified at optical level 1.

CRITERION 2 – LIGHT TRANSMISSION.  This criterion evaluates the shade homogeneity of the LCD filter — whether areas are lighter, darker, or perfectly uniform — thus classifying light transmission as 1.

CRITERION 3 – LIGHT DIFFUSION. This criterion evaluates light transmission, meaning the light that passes through the filter without diffusion or a larger halo effect.

CRITERION 4 – ANGULAR DEPENDENCE CLASS. This criterion evaluates the variation in shade darkness based on the viewing angle of the filter (for example, when welding overhead, there is a tendency to look through the filter at a different angle). When the shade remains the same, the classification is considered homogeneous. The higher the classification and quality, the clearer the filter needs to be for the LCD to maintain uniform shading.

For example, if we purchase a welding helmet whose filter has an excellent reaction speed and an OPTICAL QUALITY RATING OF 1/1/1/2, this means the helmet features:

CRITERION 1. Excellent optics. (1)

CRITERION 2. Excellent light transmission class. (1)

CRITERION 3. Excellent light diffusion class. (1)

CRITERION 4. Good angular dependence. (2)

Switching speed: The shortest switching speed is 0.02–0.05 milliseconds, which is only achievable with LCD filters powered by both batteries and solar cells. Welding filters powered solely by solar cells can reach a switching speed of 0.1–0.3 ms; even so, this reaction time is not poor, as it represents one tenth of one thousandth of a second — a speed virtually imperceptible to the human eye.

It is important to verify the manufacturer and the technology behind each brand. For example, the LONG BATTERY X10 technology featured in SKOLTS brand welding helmets is particularly noteworthy, as it uses triple AAA batteries. This not only improves the switching speed but also extends battery life by a ratio of 1 to 10.

What are solar cells used for? Solar cells provide power to the filter and, in some models, may be the sole power source. One advantage is that batteries are never required; however, this does reduce the switching speed and service life.