Re: Buffered matboard

Frank Schanberger (fschanberger@ucsd.edu)
Fri, 06 Feb 1998 09:16:08 -0800

I found that the term "acid free" usually meant that a buffer like Sodium
Bicarbonate was being used on the material not just that it was free of
lignum(?) or wood pulp products. Because of this I have steered clear of
anything advertised as acid free or buffered and have actually used
"non-archival" boards such as the ultra black letraset for some color work.
When one looks at the pHs listed for some buffered boards from Light
Impressions (8-10) it looks like the acid-free will be more harmful than
helpful. I would even go as far to use non-buffered board for everything
except silver gelatin.

Francis

>The bottom line is do not use buffered matboard with cyanotype. Also watch out
>for buffered paper boxes and paper that might come in contact with cyanotype
>prints. Buffered materials are used so that the base incorporated will help
>neutralize the acid which forms from lingum in the paper and/or acids that
>come from sulfer dioxide in the atmosphere. The base will bleach the cyanotype
>prints. It may take a while, but eventually it will, especially if the
>humidity
>is over 40-50 %. I have been told that Rives BFK is buffered so every time I
>buy a new batch, I check its pH. Why bother with buffered matboard. Why not
>use a good grade of acid free matboard for everything?
>
>Bob Schramm