hist-brewing: bottles

Mills, Scott Scott.Mills at COMPAQ.com
Mon Aug 28 08:49:55 PDT 2000

On an interesting and related note.  While in the supermarket this weekend I
happened to notice 6-packs of Bud in brown plastic screwtops.

and Al said:
> It doesn't happen *just* from UV light, although UV does 
> skunk beer.  Light
> from the blue-green range to UV will skunk beer.  Plain clear 
> glass passes
> very little UV, so it some light in the visible spectrum 
> needs to be involved.

OK yer right.  The visible spectrum run roughly from 400 nm to 700 nm.
Below 400 nm is UV  above 700 nm is IR.  Technically light of wavelengths
from 550 nm  (roughly blue-green) and below can cause photochemical
reactions in hop resins therefore the lower half of the visible spectrum
does contribute to skunking.

Beer will skunk more quickly in sunlight than it will in normal incandescent
or fluorescent lighting because of the full spectrum (including the
additional UV) in the sunlight.  This can make the difference in only
minutes needed to skunk in bright sunlight and days needed in artificial
light.  This is an experiment that I have done and your beer will skunk much
more quickly in sunlight than it will in even very bright incandescent

I was not aware that clear glass bottle provided any significant UV light
protection.  True some clear glass does block UV but not all glass does.
You can buy special window glass or tinting that blocks UV or special glass
for your picture frames that will block the UV to protect your fines art.
Most photographers keep a UV filter on their camera when shooting outdoors.


Scott Mills 
Scott.Mills at Compaq.Com 

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