Condition concerning daguerreotypes is probably the most over-used and least understood word in today's daguerreian lexicon. Without writing a major paper, I will briefly attempt to explain my definitions of condition and how it affects my own purchasing habits. Then, if you agree with these ideas, feel free to use them. If you don't think that I have completely satisfied the subject; I'm sure you will either ignore my suggestions or let me know what you think.
Basically, two types of tragedies occur to daguerreotypes. First, the natural aging of a plate is very dependent on how the piece was kept during its nearly 150 year life span. It is extremely vulnerable to heat, cold, direct sunlight and changes in humidity. The original cladding of the silver layer to the copper, and all the physical and chemical processes that had to happen for each successful image to be produced is quite impressive. If any one (or more) were outside the normal levels of tolerance, then it is perfectly understandable, that in combination with its storage and physical environment, strange sights might begin to appear on the surface of the plates. The most likely abnormality that first appeared, even when the owner still possessed it was a ring of tarnish. That simply was the natural oxidation process of the silver, in combination with the plate's chemistry, the brass mat, the type of tape and glue used to seal the package (plate, mat and glass) together, and the environmental equation. I personally feel that most tarnish, if it doesn't overwhelm the subject, is definitely advantageous. But in my example, the owner or the next generation of folks noticed the "discoloration" and someone decided that steps must be taken to clean the picture.
That scenario nicely dovetails with the second and greater tragedy; men, women and children becoming instant experts in the preservation of daguerreotypes. The pattern emerged a few years after the introduction of daguerreotypes in 1839 and unfortunately is accelerating at an even greater pace today as I write. And let me be quite frank. The highest majority of persons who take apart daguerreotypes should stop immediately, especially those folks in conservation labs whose specialties are paper preservation. Oh, the stories I could tell!
Since I have suggested that human handling is most responsible for the largest amount of plate damage, why should daguerreotypes be taken apart?
Personally, I have reglassed and archivally resealed approximately 7,500 daguerreotypes and the three motivational factors were: I needed to know what the mat hid. I wanted to see each image without all the degradation on the glass and I firmly believed that I was preserving each precious piece for future generations.
I quickly realized that a large percentage of the plates I examined had been taken apart previously, even when I broke what appeared to be original seals. Several indicators were: An earlier layer of tape was visible, sometimes only seen with a good loup. If there were already mat abrasions present and a much more obvious clue. If the plate was sealed with green tinted glass, no matter how old the tape appeared, I knew it had been unsealed previously. The very earliest images were sometimes sealed with light blue or light amber colored glass, but I can't ever remember seeing green glass originally used in the 20-year era. This little known fact should impress your friends!
When I buy daguerreotypes, I am a stickler about condition. If a plate has any evidence of having been damaged because of the human factor, I either quickly return it or ask for a large reduction in price if the seller has disregarded "condition" as a factor in the value. Of course, there is always the beauty and rarity of an image that must be considered. I have sold some very important plates (at high prices) and I still have several in my own collection that have seen too much human abuse. Some of the obvious problems are: Fingerprints, scratches, wipes, dings in the surface (when a plate has been dropped while uncased), bends and cleaning the surface (and there are a variety of methods, none of which is any safer or better than the other, because each time a plate is cleaned the amalgam is being irreparably changed and damaged).
I left cleaning for last, because while it might come as a terrible shock to many daguerreian lovers, I will estimate that approximately 75% of all the daguerreotypes not still in original seals (of which maybe 20% remain), have been cleaned at least once. There are many telltale signs that will be discussed later. Because a daguerreotype has been cleaned (if it still retains much of the natural brilliance, although most of the added colors are probably dim or gone) it certainly shouldn't be shunned. Some of my greatest portraits in my own collection were previously cleaned. I personally refrain from cleaning plates unless tarnish or certain types of spots completely cover an image to the extent that it is a visual wasteland. Cleaning hand-tinted pieces will result in disaster.
For the naturally occurring minutiae that can congregate on a plate, let me say that "beauty must be in the eye of the beholder". On certain kinds of portraits, I can overlook serious natural plate faults, especially if the object was made during the experimental, very early period, from September of 1839 to the end of 1842. It takes a basic knowledge of daguerreotypy to understand that not many operators produced perfect plates then. They were just glad to see a cold, blue/gray face on a poorly buffed surface. By 1843, masterful daguerreians consistently sought technical and artistic perfection. There are many extant plates that provide us with proof of their awesome achievements.
Most commonly seen on daguerreotypes from the entire 20 year period is surface dust, white or beige mold spiders, silver tarnish, blue or brown spots and areas of scum deposits that were caused when the older glass leached out some of its impurities onto the surface. Taking that thought further, if a microscopic shard of glass pierced the silver layer, then it is possible that copper corrosion, in the form of green eruptions on the surface, will be visible.
Less common elements are daguerreian measles (tiny black dots sometimes visible through an 8x loup), a white or bluish haze (but not tarnish), residue from wax on the copper side of the plate, and exfoliation of or bubbles in the silver layer.
One element that isn't totally understood and has been misidentified with cleaning daguerreotypes, is the common appearance of daguerreian frosting. These are tiny white grains that are usually seen in the very blackest areas of a plate. Many daguerreians attempted to "boost" the richness of their blacks using different chemistry and instead of a solid black, they created this phenomenon. A small percentage of plates actually have the frosting effect so it can be seen with the naked eye, but if it is on the surface, my scans will find it and usually make it appear much stronger than it really is. Remember that frosting isn't a condition problem, it is purely an aesthetic factor.
The scans shown below exhibit some of the condition problems.
Mold spiders are white or beige tendrils, sometimes that have an elevated, well-defined center, that grow on the surface of the plate. They are very difficult to remove and should be considered permanently visible when considering a purchase.
Green spots and blue/white haze are graphically illustrated. The green spots, if they are removed, leave "pits" through the silver into the copper layer. I wouldn't advise touching them, so they also must be considered as permanent fixtures. The haze can be caused by several factors and my experience is that a soaking in distilled water will effectively remove it about 50% of the time. Otherwise, even most methods of cleaning the silver won't be successful. You have to consider how much you will still like an image with the haze present before you decide to purchase it.
Most plates will have acquired varying amounts of dust and grit on the surface. I use a commercially available, canned air product to careful remove whatever I can. It is difficult to know just what can be blown off. Sometimes I will soak a plate in distilled water to "loosen" the grit and then dry the plate, from top to bottom using the canned air.
Scum can occur naturally or be a result of an improperly cleaned and rinsed plate. Soaking in distilled water is about the only method I would recommend and my rate in successfully removing scum is about 20%.
When tarnish covers such a large portion of the image, as in this example, it is almost advisable to clean the silver, using your tried and true method. Unfortunately, I think someone made the attempt earlier and also badly scratched and rubbed the surface. The condition couldn't be much worse, until you look at the next scan. This poor little chap was defenseless against the moron who poured liquid silver cleaner on the surface and began to rub. When they realized the damage that they were inflicting, they stopped. Not knowing what else to do, they put the mat, glass and brass protector back together, without even attempting to rinse the piece.
Another of man's faux paux, and one of my favorites, is the fingerprint, graphically shown above the man's forehead. Tarnish and a few more scratches are also obvious.
The brightest white specks in the darkest regions of the man's coat is daguerreian frosting. The other flecks are superfluous, caused by enlarging the scan.
Finally, I thought I might end this information session with an example of an absolutely pristine daguerreotype. Not only is the condition perfect, but every technical aspect is outstanding. Technical excellence will be addressed at length in the future.