Drawing on that rare commodity, common sense, is what Steven Weintraub has built his career around. That he has highly honed reasoning skills was evident in his AIC general session presentation on the evolution of environmental standards. Weintraub starts his presentation with reference to Gary Thomson’s The Museum Environment. According to Weintraub, the environmental recommendations that Thomson made in this book reflect a practical knowledge gained over time and based on common sense. Since that time, the conservation profession has place environmental controls that move us farther away from the target.
Weintraub advocates that environmental requirements to preserve artwork are complex systems that have been over analyzed or over simplified. Environmental controls should be based on risk assessment concepts. What level of risk is your institution willing to tolerate? In conservation, our risks should be like insurance actuarial – our environmental controls should be driven by costs and practicality of implementing environmental standards. We must be wary of the one size fits all type of environmental standard, recognizing that conditions that are right in Santa Fe will not apply to New York.
Environmental discussions have circled around recommendations like 40%-60% RH versus 45%- 55% RH, and 16-25 deg C versus 20-24deg C. One approach is to look at the way materials respond to humidity and choose the best set point for all materials – this leads to that 40% RH to 60% RH range. But other factors need to be considered. Environmental standards do have some positive influences. In existing buildings, the ability to maintain such standards has an impact on the operational procedures that may lead to operational and physical improvements. These standards influence the construction of new buildings.
Weintraub then addresses lighting issues and the display of artwork. Originally, light issues were driven by defining the lowest amount of light needed to accurately see the artwork and nothing more. Again this was a practical and common sense approach. Then we moved away from this way of looking at lighting issues and turned to the concept of annual exposure. But annual exposure is a managerial tool, not a conservation tool. For example an object exposed to 50 lux for 8 hours a day for 90 days does not experience the same amount of possible light damage as object that receives 150 lux for 8 hours a day for 30 days. The most important concept to take away is to make every photon count. In moving forward we must return to the common sense past.
The recent trend is studying artwork using microfading testers continues to focus on damage issues. Weintraub feels that this emphasis is overrated. When you use a microfading tester to study artwork, where in that lifetime prediction curve are you for the object? Instead he advocates going back to the idea of lighting the object just enough to see the object without doing damage.
He points to the Harrison report from the early 1950’s that shows that the damage to an object is relative to the wavelength of light to which it is exposed. Spectral damage calculations can be made based on this work that allow you to calculate the amount of damage per lux based on wavelength and specified material. Then you can choose your light source. For example, daylight has two times more damaging than tungsten light.
Next, Weintraub turns to environmental monitoring systems noting that these are really problem solving tools. But what should our metrics be? We need to keep in mind that there is a hierarchy of conditions that affect visual appearance that we perceive. This hierarchy can be things like color temperature or color rendering. These are the conditions that Weintraub feels we should monitor.
In the end, Weinstraub states that we are looking at complex systems that have a pattern. We need to sit down and look at all the data, consider the risks, and try to perceive the patterns.