One quick way to rule out many prints as being made more recently than 1951-52 is to use a black light. A black light is just what it sounds like, one of those holdover fluorescent lamps from the 1960s psychedelic parties for those of you old enough to remember or those of you into 60s retro. You can buy a decent one at Radio Shack for about $30, or a handheld one is available usually through stamp collector supply houses. I bought my handheld one in Paris at such a shop.
While you are out shopping for your black light, remember to pick up a pair of ultraviolet (UV) plastic glasses. I got my set at Home Depot. This will help prevent damage from the black light to your eyes.
If the print glows in the dark under black light, it was probably printed after 1950-51 (if on European paper) or 1953 (if on American paper) due to brighteners that were added to some photography paper starting around that date. It used to be thought that the cut-off date was 1955-56, but recent evidence suggests that those dates given by manufacturers may have been the expiration dates of the paper instead of the creation dates, which are about two-three years earlier. If the photograph glows only in the baryta layer (the emulsion), then it may be one indication that it is very early to mid-1950s, because apparently that was where brighteners were added first. However, let us stress that should only be ONE indicator of date. According to the conservator Paul Messier, only 1/3 of the prints he has so far tested from the late 1950s have brighteners and only 3% from the early 1950s; his survey found peak use of the brighteners from 1960-64 and then post 1980, when papers made with brighteners made up 78% of the papers sampled so far. Oddly enough use of brighteners dipped substantially from 1965-1979, so care must still be used in dating many photographs.
If there are spots or smudges of glowing areas, the image, which may be vintage, was probably washed/restored/treated in some way. Look for evidence of that treatment (tears, etc.).
Some prints may have been made on hand-coated paper. These prints may actually glow in the dark even though they are vintage prints, because brighteners were added to papers very early--just not to commercially produced photographic papers. Some varnishes or other surface treatments may also fluoresce, but with practice an experienced observer can tell the difference.
You can usually get the major auctions houses here and in London to black light most prints for you. But I recently found that some of the houses were using weak hand-held black lights in daylight to check. When I used a plug-in in full darkness, many of the same images that they had said had passed the black light test did not! In Paris and other European venues, it is doubtful you will be able to get the house to black light the image, but you may be able to arrange for a private viewing where you may be able to black light selected items. Bid as if the item is not a vintage print if there is any question. A few dealers carry hand-held black lights, but I have never seen anyone use them at the auctions themselves, which is difficult to do under normal lighting conditions in any case.
Remember that the print itself actually has to glow rather than simply reflect back light. You may find it takes some practice to tell the difference. Just look at some copier paper under black light to see what I mean about glowing.
Remember that if a print does not glow, it does not mean it is a vintage print automatically. Many current papers do not contain optical brighteners. Other tests may be made on a paper to determine when the paper, not the print, was made. Look for signs of oxidation in the shadow area and physically examine the print for clues to its age, but remember stamps, manufacturing logos, signatures, dirt, etc. have been faked in some cases, particularly on Man Ray and Lewis Hine prints. In a few cases whole classes of photographs are suspect, such as many Russia images that were made on paper to resemble earlier papers (including a lack of brighteners).
If in doubt, talk to your conservator, who can request paper pulp analysis to determine the vintage of important 20th century images. The test does require a small bit of paper be destroyed, although edges are one way to accommodate these tests. The test runs about $500, so make sure that your print is worth it. And, again, the test is not 100% certain. Some papers still do not contain bleached kraft wood, which is what the test primarily looks for.
When looking at 19th-century prints, watermarks can help date the print, as well as other visual clues (the coating thickness, etc.).
Unfortunately while all these methods may rule out an image as being vintage, they don't confirm that an image is vintage--just make that likelihood more likely. Conservators have been working on some more definitive tests to determine age, and we will try to keep this article up-to-date on all those developments.
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