[Jewelry making - Article 00661] - Re: [Orchid] Infrared light

[Mike Aurelius]

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    Donna - Yikes, Gentex of all companies! Yes, I believe that the
    information provided is inaccurate and incorrect. 

    Here's what Z87.1 says are the general standards for a shade 5
    welding filter: 

	Maximum Luminous (Visible) Transmittance: 3.16%
	Nominal Luminous (Visible) Transmittance: 1.93%
	Minimum Luminous (Visible) Transmittance: 1.18%
	Maximum Effective Far UV Average Transmittance: 0.04%
	Maximum IR Average Transmittance: 5%

    This is from Table 1, ANSI Z87.1, 1989. 

    My guess is that they are fudging the numbers by messing with the
    visible transmission. I can't see how they can achieve a maximum
    visible light of 3.16% and still call it a shade 5. And actually, the
    lie is directly in the print: "Available in all conventional sizes
    and shades.  Substituted shade-for-shade gives protection equal to
    green glass. Increased apparent brightness in shade-for-shade
    trade-off is non-harmful." Then followed by "Meets or exceeds all
    ANSI Z87.1 standards." 

    You cannot have an increase in visible light transmission and still
    meet the standard for the shade number. 

    Now, having said all this, since I don't know what the UV and IR
    transmission of this lens is, I cannot say how "safe" for your eyes
    it is. You can assume because of the polycarbonate base that it is a
    good UV filter. You can also assume that with the Gentex name on it
    that it is going to meet the IR standard. However, you know what
    happens when you assume too much... 

    Using this filter with a kiln and/or torch may or may not be safe. I
    can't tell you that for sure without seeing a transmission chart of
    the actual filter. A true shade 5 filter WILL be safe. 

    Just curious, was this filter more expensive than a regular welding
    filter? 

Mike Aurelius

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