On Saturday, August 9, 2003, at 10:14 AM, Kennedy McEwen wrote:
I can't fully debunk it, but I think it is unlikely, due to the nature
of the problem. The yellow is damaged silicon compounds in the glass
as a consequence of the radiation and I cannot see any way that
exposure to UV would repair this.
To emphasize what I posted yesterday: In order of probability, the
'yellow', analogous to that on the resilient inorganic mineral of your
teeth, is most likely derived from organic materials. Organic chemical
binders, etc., are used in MC. Organic carbon bonds are VERY sensitive
to radiation damage; likewise, potentially can be removed. If solvent
removal of the coating can be accomplished, the yellow should "went".
Like UV treatment from a dentist or sunlight on organic stains on
sheets, organic stain can be "bleached", i.e. oxidized.
What I implied, but did not stress: Glass, a 'non-crystalline' melt of
boron, silicon oxides and other elements, lacks the radiation sensitive
organic carbon bonds. Glass is so resistant to radiation damage that
zillions of $ have been invested in the development of processes for
encapsulation of extrEMEly radioactive waste for 'eternity'. Depending
on the ingredients of a specific glass, glass can be susceptible to
'fogging' or color change induced by intense ionizing radiation.
Distilling all this to the pragmatics of a discolored Zuiko from rare
earth containing coatings: First, the ionizing radiation level is
extremely low. While difficult to separate radiation induced change
from chemical degradation of the organic coatings, the science says the
damage is on the exterior of the lens, not within the inorganic glass
matrix. UV, whether device or sun generated, can be useful for
"bleaching" organic discoloration. Solvents may also work. The
obvious: once bleached by UV or dissolved by solvents, you no longer
have a MC lens with the same optical characteristics. You should have
clear glass.
Shine on...
Bill Hunter
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