There is no question that making daguerreotypes involves working with hazardous materials. Even Becquerel, the safer process, involves elemental iodine, a corrosive substance that produces fumes that can cause tissue damage when inhaled. The Mercury process adds the even more challenging materials mercury and bromine. The hazardous nature of these substances is the reason we carry out daguerreotype work inside a fume hood and take careful precautions to contain the chemicals safely when stored. Simply storing these substances safely can present serious challenges.

I recently had the opportunity to visit master daguerreotypist Jerry Spagnoli in his studio in New York City. In addition to the privilege of seeing some of his beautifully crafted and compelling daguerreotypes in person, I had the pleasure of an extended conversation with Jerry on a wide range of subjects concerning daguerreotypes, the art world and the craft itself. It was during that conversation that Jerry mentioned the method that he uses to store his mercury when not in use.

Over the last several years I have been testing various containers to see if they can store mercury without releasing mercury fumes. The containers tested have included glass with various metal lids and several seals – PTFE, rubber, Viton, HDPE and others. Additional experiments have included stainless steel flasks with metal caps, 100% PTFE containers, and glass with a ground glass stopper.

The method I used was to seal a small amount of mercury in the particular container to be tested, and place that container inside a Mason-type canning jar with a metal lid. Then the setup was tested periodically by opening the outer jar slightly and measuring the air inside with a Jerome 411 mercury fume meter. The results were similar in every case – every single tested container allowed fumes to escape into the outer containment and the concentrations were above a safe level. The concentrations varied quite a bit – perhaps mostly related to air temperature, but there was no clear “winner” and every containment method tested had leakage.

So, when Jerry mentioned mercury containment, I was all ears. He related that he has been using steel paint cans for storage – a suggestion that was new to me. Given my prior experience, I was skeptical, but on returning home, I purchased a pair of unused cans from a big box hardware store – 1 quart and 1 gallon – and immediately set up a new test. Inside the quart can was placed a small steel flask containing a 1 cc drop of mercury. That flask has a stainless steel cap with rubber seal. The quart can was closed carefully and then that can was placed in the gallon can, and carefully sealed. That setup was placed in a fume hood that is in an outbuilding – the fume hood was closed but the fan was left off.

Since then the setup has been tested three times over the course of 15 days. The mercury meter was first used to sample the air in the closed fume hood. In each case the meter read zero. Then the gallon can was carefully opened a bit and the air inside sampled. Each meter reading was zero – an indication of complete containment. Inside the quart can the story was different. Each measurement found a significant concentration of mercury fumes in the inner can that had leaked from the steel flask.

RESULTS

Date                      Inner Quart Can                               Outer Gallon Can

08/09/14              .612 mg/ m³Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â                  .000 mg/ m³
08/15/14              .755 mg/ m³Â Â Â Â Â Â Â                                  .000 mg/ m³
08/24/14              .891 mg/ m³Â Â Â Â Â Â Â                                  .000 mg/ m³

Note: The OSHA 8 Hour TWA for elemental mercury is 0.1 mg/m³

This result is a first in my experience, and well worth reporting to the practitioner community. It would appear that the initial result is that the metal paint can is achieving 100% containment. Testing will continue to determine if the seal is eventually compromised by repeated open/close cycles.

While this result is significant and of use to any practitioner storing mercury, it still remains true that the safest practice is to insure that all of your chemicals are stored in a locked, vented cabinet that is outside of living spaces. This is especially true if you have children in your home, as they are particularly susceptible to permanent health damage from mercury fumes. Equally bromine and iodine should be stored and locked-up outside, as a container failure inside a living space would be catastrophic, particularly with bromine.

Please do be aware that while paint can storage seems to be very promising as a method for storing bottles containing mercury, it is in no way appropriate for bromine or iodine storage. Leaking halogens will quickly eat through the thin metal of a paint can.

Also, this suggested method of paint can storage in no way changes the absolute requirement that mercury development be carried out in a properly calibrated and functioning fume hood. A hot mercury pot is capable of quickly filling a room with sufficient quantities of mercury vapor to create immediate and serious health consequences. The editors of CDags from time to time receive descriptions and even photos of practitioners working without hoods and using seriously unsafe pot designs. These setups are a significant health threat.

One final note: While we are grateful to Jerry Spagnoli for sharing this valuable safety suggestion, neither he nor CDags.org is responsible for the consequences of following any suggestions in this article or any other on CDags. The daguerreotype process involves hazardous materials and you are solely responsible for your own safety and the safety of your family in carrying out the making of daguerreotypes. Educate yourself and follow all recommended industrial safety practices regarding chemicals and other materials, so you can enjoy making daguerreotypes for many years to come.