Judy Seigel (jseigel@panix.com)
Tue, 30 Mar 1999 16:34:32 -0500 (EST)
On Tue, 30 Mar 1999, Sil Horwitz wrote:
> I think what Nze is concerned about is the organic optical brighteners, which
> are, indeed, dyes used extensively. While these dyes are colorless, they have
> the capability of converting light in the UV range to white light capable of
> being seen by the human eye. These optical brighteners (dyes) are used in
> almost all clothes washing compounds, which is why clothes washed in most
> popular compounds glow when seen under a UV lamp. This same test can be applied
> to paper: if it glows under UV, it contains a dye-based optical brightener. I
> am not personally familiar with anything bad about them (color printing papers
> include them) and though I haven't done any testing, they should be neutral.
> They absorb UV which might be a good thing in alternative printing methods! One
> cautionary note: these materials are water soluble and too long an immersion
> can leach them out of whatever media contain them.
>
Sil & all -- I haven't done these tests myself but have heard so many
times I figure there may be some truth to it, that, a) any prolonged
washing removes some or all of the brightener, and that b) the brightener
effect does fade in time. Which is not to say the print couldn't be
RE-brightened, if such is your desire.... but I note that Jeff says his
looks fine after x # of years... I wonder how it would compare side by
side with a newly brightened print..
Judy
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