I'm sure they haven't changed their formula in 200 years, but rags
sure have changed their content in that time. From the early 70's
to the early 80's I started noticing spots of polyester "contamination"
in art papers (including BFK, which I have used more than any other
paper). These were translucent, fused "goobers" (nice scientific term)
which were easy to spot by holding up the paper to light.
I don't know if paper manufacturers have gotten better about getting
the double-knits out of their rag supply lately or not as I haven't
looked at that much of it lately.
>
> I checked out this statement with a local reseller of art products and
> he confirmed this to be true. He also says that photos done during or
> before the Civil War have better archival quality because wood pulp
> paper was not manufactured until then.
Pulp paper became common several decades before the ACW. If you examine
microfilms of early documents, such as newspapers, you can almost
pinpoint when. In the 18th century, the records are in pretty good
shape because the newspapers were printed on rag paper. Around
1820-1830, there is a period of a decade or more when it is almost
impossible to find anything but fragments of newspapers. This gradually
improves until the 1860's when most newspaper records are relatively
complete again.
I don't know at what point photographs were routinely printed on pulp
paper as opposed to rag paper, but I'm sure it happened much later than
newspapers. However, also remember that in the US at the time of the
Civil War, most photographs weren't made on paper anyway, but on metal
(tintypes) or glass (ambrotypes).
Carson Graves
carson@ileaf.com