[Sca-cooks] Drummond on Butter
edoard at medievalcookery.com
Thu Jun 26 06:09:48 PDT 2008
--- On Thu, 6/26/08, Terry Decker <t.d.decker at worldnet.att.net> wrote:
> From: Terry Decker
> Subject: Re: [Sca-cooks] Drummond on Butter
> Date: Thursday, June 26, 2008, 8:18 AM
> > Without intending to muddy the waters further, am I
> mistaken when I
> > recall being taught in school that glass filters out a
> lot of the UV
> > spectrum from natural sunlight?
> You are quite correct. Glass filters out UV light.
Actually that's only partly correct. I know that UV light is a big problem for art museums. It damages paintings and such, even when they are covered by glass.
Ordinary glass is partially transparent to UVA but is opaque to shorter wavelengths while Silica or quartz glass, depending on quality, can be transparent even to vacuum UV wavelengths. Ordinary window glass passes about 90% of the light above 350 nm, but blocks over 90% of the light below 300 nm.
[ http://en.wikipedia.org/wiki/Ultraviolet ]
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