“Simple Method for Monitoring Dust Accumulation in Indoor Collections,” by Bill Wei was the first session in the Collections Care specialty section that was given on Thursday afternoon. As a museum technician in Preventive Conservation, dust is something I deal with on an almost daily basis. I thought that Bill’s talk could lend some valuable insight to my work, and I wasn’t wrong. Bill Wei is a Senior Conservation Scientist at the Rijksdienst voor het Cultureel Erfgoed, and in his session he presented on a simple and easily implemented way a museum could monitor how fast dust accumulates in an indoor collections space. He used the Museum de Gevangepoort and the Galerij Prins Willem V to demonstrate how the method.
The talk started off with a humorous introduction by Bill about views on dust in museum spaces. How for some people, museum professionals in particular, we can take a defensive stance on dust as if it implies we aren’t doing our jobs. For other individuals, dust adds an element of age that seems appropriate. He also mentioned that when the words “dusty museum” are googled the result is over 12,000 hits. Apparently more than just museum professionals see dust. Bill brought up the fact that dust is not only an aesthetic issue in museums, it can present chemical and health issues, and it can be costly and timely to remove. The two sites were then introduced, both of which house collections and are historic buildings. Construction was being done near the sites, and there was a concern about how much more dust accumulation this might cause, so they provided a good case study. Bill then introduced the question of how do you monitor dust?
Bill explained that dust on the surface of an object causes the light to bounce off in many different angles, as opposed to at the same angle, this makes a surface look matte. The resulting matte surface can then be considered to have lost gloss. This loss of gloss is something that can be measured using a glossmeter. The type of glossmeter used during this test was made by Sheen manufacturers. Bill was careful to point out that this test doesn’t measure how much dust you have, but how quickly it will accumulate. For this run of the test Bill used microscope glass slides, because they are cheap, reusable and glossy. The steps of the test are as follows:
- Using the glossmeter, measure a clean slide on a white background (copy paper is suitable. This should be the same background used throughout testing.)
- Put slides out at various locations you wish to test, remembering that the more slides you put out, the more work you will have to do. The slides should be placed in out of the way locations and staff should be told about them.
- After a predetermined amount of time (ex. one month), using the glossmeter measure the slide on the same background that you used in step 1.
- Clean the slide, and reuse, starting over at step 1.
The calculation that is then used to determine the rate of accumulation of dust over the time period is
Fraction change= (Dusty Slide after 1 month measurement – Clean Slide measurement)/ (Clean slide measurement)
Multiply that by 100 to get the percentage.
Bill explained that for every month that you take a glossmeter measurement, you add the value of the new measurement to the previous, since this is cumulative you will go over 100% at some point. You can then use these values and plot them in a graph over time.
If you wanted to test the dust samples, to find out where the dust was coming from and what it was made of, you could incorporate small conductive carbon stickers on the slides. Since this talk focused on the accumulation, not the source of the dust, this topic was not discussed in detail.
The placement of the slides was at one point done both vertically and horizontally surface. The vertical placement was done to mimic how much dust a painting might accumulate. However the vertically placed slides needed a much longer period of time to really show a loss in gloss, so it was not considered as necessary to run both types of slide placement.
When it came to analyzing the results of this test one thing that was found was the fact that the slide nearest the entry had the most dust. When it’s results were plotted onto a graph it produced the steepest slope over time. The more visitors a museum has, the more dust accumulation occurs. During peak tourist times there was a correlating peak in dust accumulation. One thing that was also noticed at the Museum de Gevangepoort was that during construction periods there was also a rise in dust accumulation. The results confirmed a long held thought that visitors are one of the main sources of dust in museums.
Bill then talked briefly about the chemistry of dust. When the dust was analyzed it was found to contain salts, iron, chalk, sand, clay and concrete among other things. When the makeup of the dust was looked at, it was possible to notice trends, for example during the winter months, February in particular there was a noticeable rise in the amount of salts found. Looking at what the dust was comprised of could allow scientists to identify the source of the dust.
Bill pointed out that the idea of too much dust isn’t really something that is definable in terms of science. It’s more defined by people’s perception of it. Different surface types can be just as dusty as one another, but if the dust is more visible on one type of surface, say plexi, the viewer read’s that surface as being less clean.
In discussing an action plan for dust monitoring Bill said you have to determine why you are doing it, i.e. to see if your new HVAC system is producing better results, and it’s important to define “too much dust” as a difference in gloss.
The questions asked after Bill’s presentation included, how many/ what angle should a gloss measurement be taken, to which Bill answered one measurement at 85 degrees was sufficient. He was also asked how often one should be taking measurements. He said that three to four weeks at most will produce good results, if you measure too soon a change won’t be seen.
Bill’s presentation was informative and lively. He presented a system for testing dust accumulation that could easily be implemented and followed. Thanks to Bill for a great talk!