RE: Sources for wet plate collodion chemicals

Dianne wrote:

> The Rockland process (WHEN it works, which is only about 1/2 the time)
> produces "coffee and cream" whites and blacks that are dark but not
> truly black - very much consistent with the tintypes I have seen that
> are pre-1870.

> However, since people have been bringing their family tintypes for me
> to examine I have seen a different "class" of tintypes where the
> whites are bright and almost pure white and the blacks are almost
> pitch black. On these, the detail and sharpness are VERY good. They
> are home-grown "tintypes", often on rough metal plates (some, I swear,
> must have been cut with an ax!), and the thickness of the emulsion and
> the way it is spread on the plate would lead me to suspect that they
> are some form of collodion but not wet plate images and they are
> definitely NOT factory made plates. The "bright" plates I have seen
> were made by photographers in southern Ontario, Chicago, Minneapolis,
> and other unknown points in the north central U.S.

> I'd sure like to know what changed in the 1880's to start producing
> some of these brighter images.

I am not aware of any other process that was commonly used to make
images on japanned steel plates -- if you have images on blackened
steel plates, they were almost certainly made using the wet collodion
process.

There are probably several things going on here. The rough edges may or
may not mean something -- tintypes were often trimmed by their owners
after purchase. Also, tintypes were the "poor persons'" photographic
medium, being much less expensive than ambrotypes and often produced by
less accomplished practitioners. Accordingly, they varied all over the
map in initial quality, as well as receiving less care in subsequent
years (some were stored in albums, some left lying on desks or tacked
on the wall, some were carried around in wallets or lockets; some were
after-coated with a protective layer of shellac and some weren't, some
were fixed properly and some weren't, etc.). As I mentioned in my
previous post, collodion is only semi-permeable to water (and thus, to
processing solutions) even while wet. This is a big variable in
wet-plate work. The coating is drying the entire working time, so
sensitizing, exposure, development, and fixing must be done promptly
after coating for best results. Slow workers got inferior results.
Also, tintypes were mostly made by itinerant photographers working out
of tents, many of which let in enough actinic light to partially fog
the plates. Of course, contamination and/or exhaustion of the
processing chemicals was common in such an environment, and washing
of the final image was often inadequate.

I can corroborate the wide variation in quality (and, in particular,
brightness) of tintypes found today, but have not noticed any
correlation with date of production.

Best regards,

mm
Received on Tue Aug 30 11:49:06 2005