Two years ago I produced a few extra daguerreotypes while futzing about with a new development system that in the end didn’t work out for me. Those few extra plates however did give me a chance to conduct a rather oversimplified accelerated aging test, and to test the two materials I usually use for mats to see how they would perform under stress. A while back I promised someone I would post results of my aging experiment, and so here it is.
It should be noted here that proper storage of daguerreotypes would of course involve not having them in places where direct sunlight repeatedly hits their surface, and that they should be kept away from excessive heat and moisture.
Daguerreotype image is made of silver/gold/mercury amalgam particles resting atop a layer of pure silver. Having essentially no protection from air, that silver plate is sealed under glass with some sort of a spacer that acts as a mat, separating image from glass. Material chosen for that spacer and the kind of sealing tape one uses are two major factors in how well the plate will survive overtime. Any harmful chemistry trapped in the mat, and any air or moisture leaking through the sealing tape will result in tarnishing. High temperature will of course accelerate any chemical reaction, and UV light is also known to be a catalyst. Without going into too much detail I will say that most tarnish on daguerreotypes can indeed be cleaned with careful modern methods, but it is my aim to have my plates go as long as possible in their original state and without need for restoration. With how little was known abut archival methods 175 years ago, and how poorly plates were sealed back then, it is remarkable how many daguerreotypes survived all those years in incredibly clean condition. It is my hope that with better quality matting supplies my images will exhibit only a minimal change in at least 200 years.
Here is how the two 1/4 plate sized images looked when they were made in March 2019.
I sealed the plates on July 6th 2019. Plate 1 was sealed with the regular paper mat, while plate 2 had a plastic frame spacer instead of paper mat. I didn’t bother adding the finishing tape that I normally put over the actual sealing tape to make presentation look complete; that tape is very easily removed and maintained, and it lives outside the enclosure, so won’t affect anything tarnish wise. Here is how the plates looked right after sealing.
For the next two years I kept them in same position. In San Diego there’s on average about 150 days per year without a cloud in the sky, and about 120 days with very light partial clouds, so for at least 270 days each year the plates were bombarded by direct sun. Every once in a while I would take a temperature reading from the back by using an infrared thermometer, and even on mildly warm days in a closed car the plates would regularly heat up to 140-150°F (60-68°C). I have also taken these plates into subfreezing temperatures on multiple road trips. Morning dew point can be pretty brutal when living only a few miles from the ocean, and with windows of my car often left rolled down, I’m sure there were many times when these plates got rather soaked.
Not being a trained conservator or archivist, I can’t say with much precision exactly what the conditions to which I subjected my plates were equating to in terms of normal recommended storage. I do suspect though that subjecting my plates to intense heat and direct sunlight for two years probably sped up any tarnishing or other deterioration by at least a factor of 50, so I unsealed them on July 6th 2020, and here is how they appeared, showed here side by side with their original condition.
When unsealing the plates, I was reassured that the tape I use will withstand pretty much anything; after all that heat it didn’t come undone even a tiny bit in any spot around the perimeter. I was surprised to see that the paper mat that I know to be the safest for daguerreotypes still left a mark, while I see almost zero trace of the plastic mat. A few tarnish spots also seem to have appeared; they are rather minor and I suspect my washing and drying procedure may be partially to blame. Overall though, if this is how much change my plates are to expect after 100 years of normal indoor storage, I’m happy. Seeing that chemical reactions within enclosed environment tend to slow down and eventually seize altogether, it is not outside the realm of reason to suggest that whatever tarnish is seen after 100 years, won’t actually look twice as bad in 200 years, but in fact may just look 10% worse or not at all.
On the other hand, here are a couple examples of what happens when if an incorrect mat is chosen. The bare plate you see with no mat on it was one of my early Becquerel developed images, and I sealed it with a regular mat that is advertised as fully archival. It was stored in the dark at room temperature, and unsealed 3 years after, revealing major tarnishing around the cut edges of the mat. The second plate is not shown whole, as it is the work of another modern daguerreotypist. This plate was made and sealed in 2018, so it has been in contact with this mat for 3 years. It hangs in my studio, on a fairly dimly lit wall with no sun anywhere near it. When I got it, I didn’t see any of that tarnish around the edges of the spot in the sky. Mat choice is very important; if only 3 years can do this much damage while storage conditions are generally favorable, imagine what plates sealed with such mats look like in 100 years.
I hope this information will inspire caring artists to look more closely at how they finish and present their work. Those who are in this for the long haul may want to consider running similar tests on materials they prefer or would like to consider using. When working with daguerreotypes time slows down, and so a coupe of years of waiting is nothing when it comes to pursuit of higher quality.
Anton
No comments:
Post a Comment