Re: paper and optical brightner


Jeffrey D. Mathias (jeffrey.d.mathias@worldnet.att.net)
Tue, 30 Mar 1999 15:23:08 -0500


Nze christian wrote:
> I asking for some advice about paper and optical brightner.
> As one of my favorite paper contain optical brightner I want to know if it
> act on the archival quality of the paper.As it is a dye it will last a time
> and will fade to let the paper is natural brightness. is it the only
> problem?
> or should I better stop using this sort of paper.

An optical brightner generally (and roughly) works by changing UV light
into white (or blueish) light. This can also be called "fluorescent
whitening agent". The brighteners referred to by jewelia (bleach,
titanium dioxide, etc.) are really behaving as chemical brighteners and
are not functioning as a true optical brightener. The key word here is
"optical".

An optical brightener I have used many times is made by Sprint called
"Print Brightening Converter". Details of its use can be found in the
Pt/Pd Guide on my web site. The actual optical brightening agent is
manufactured by Ciba Geigy and is an organic compound
called
"2,2'-(1,2-Ethenediylbis((3-Sulfo-4,1-Phenylene)Imino-(6-(Diethylamino)-1,3,5-Triazine-4,2-Diyl)Imino))Bis-1,4-Benzenedisulfonic
Acid, Hexasodium Salt"
At least that's what it's called on the Material Safety Data Sheet.

Anyway, I have been very pleased with some of the results. It can make
a yellowish looking paper look neutral white. It is interesting to note
that even incandescent lights have enough short wavelength light to make
this stuff work. However, a disadvantage is that the amount of
brightening will vary with different light sources, therefore it is
important to evaluate the print under the same illumination as it will
be displayed.

A nice feature is that the process is reversible. By washing the print,
the optical brightener will be removed. As to the archival nature in
your question, the best I can answer is that I have prints that were
treated six years ago and the brightener is still working. I have not
found any evidence of either image or paper deterioration.

The particular paper you are using may or may not have the same stuff in
it.

-- 
Jeffrey D. Mathias
http://home.att.net/~jeffrey.d.mathias/



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