----- Original Message ----- From: "Don Williams" <dwilli10@xxxxxxxxxx> To: <rollei_list@xxxxxxxxxxxxx> Sent: Monday, May 30, 2005 12:23 PM Subject: [rollei_list] Re: Old film > At 05:10 PM 5/28/2005, Dick wrote: > . . . . . > >> Silver is more stable than dye but is actually not >> very >>stable unless toned. Silver sulfide is extremely stable. >>Silver sulfide images are the result of using any of >>several >>Sulfiding toners, often called Sepia toners. Kodak Brown >>Toner and the very similar Agfa Viradon are examples of >>such >>toners. > > I think I have a variety of prints, some of which may be > tintype, in a box > I picked up from my stepfather many years ago. I think > some of them are > indeed tarnishing a bit. Any suggestions. (I haven't > even looked in there > in a couple of years, since some of the photos were in > mounts and I didn't > want to sort out the broken glass, guess it's about time. > > DAW > > Tintypes, more properly Ferrotypes, are photos made by coating a very thin sensitive layer on polished metal. Since silver in very thin layers is reflective, a direct positive is had by making the backing black. The silver image looks white in comparison. Tintype coating may be gelatin but many were also made using collodion. Restoring them is really a job for a professional conservator. Regular prints can show the effects of oxidation of the silver by "mirroring" or "bronzing". This is an effect where the image silver is oxidized, the oxide being extremely fine is able to migrate to the surface where it may be again reduced to metallic silver by other pollutants. The result is a noticeable shiny area especially over the denser portions of the image. negatives, in principle, are also subject to this redox effect but the image silver grains are so much larger than print grains that the effect is rare. There are treatments that can remove the surface material. They consist in general of bleaching in a permanganate bleach and redeveloping. Any such treatment can destroy the print so the best procedure is to make the best copy negative or scan possible before trying any remedial treatment. Kodak has a couple of good books on identifying and preserving old images. I have to search mine out to give you publication data. Again, its wise to consult a professional before attempting anything other than copying damaged old images. I am not sure if your reference to broken glass refers glass slide mounts of glass plate negatives. The emulsions of broken glass plate negatives can often be transferred to a new support. There are techniques for stripping both gelatin emulsion and collodion (wet plate) coating but I am not an expert. --- Richard Knoppow Los Angeles, CA, USA dickburk@xxxxxxxxxxxxx --- Rollei List - Post to rollei_list@xxxxxxxxxxxxx - Subscribe at rollei_list-request@xxxxxxxxxxxxx with 'subscribe' in the subject field OR by logging into www.freelists.org - Unsubscribe at rollei_list-request@xxxxxxxxxxxxx with 'unsubscribe' in the subject field OR by logging into www.freelists.org - Online, searchable archives are available at //www.freelists.org/archives/rollei_list