Part IV of Planning a life Cycle Analysis Library


Life Cycle Assessment of Cleaning Systems

Part IV of "Planning a Life Cycle Analysis Library of Preventive Conservation Methods"

This is the fourth post about the activities of the FAIC project to plan for a Library of Preventive Conservation Life Cycle Analysis (LCA). The project is funded by the National Endowment for the Humanities through a Research & Development Grant, 2017-2018. The first post oriented you to the project and the second to Life Cycle Assessment (LINK). This post, prepared by Sarah Nunberg, describes how the evaluation of cleaning systems used by conservators in treatment of objects.

This article describes the research and results of an LCA conducted by Northeastern University students Sihong Chen, Samantha Kinnaly, Zixuan Qi, led by Professor Matthew Eckelman and Sarah Nunberg. Images and graphs provided by the students.

For all our LCAs in this planning project, we have prioritized studying activities and resources with relevance across the spectrum of exhibition and conservation situations.  This time, rather than compare objects and their exhibition, we wanted to examine items that conservators might consider for treatments. This second LCA was approached in two parts: A and B.  Part A examined forty cleaning agents (solvents, water, and detergents) that the NEU students selected from a list of over 200 agents. Part B examined six specific systems involving solvents, buffered water, and gel systems.

 LCA: Functional Unit

The role of the functional unit is essential to each LCA study. In Blogpost #2, we discussed defining the goal and scope of the project and how we set the system boundaries.  For this project (LCA 2), the goal was to identify the environmental impact of forty cleaning agents often used by conservators, and to identify the environmental and human health impact of six cleaning systems considered for one treatment. The system boundaries in both Part A and B was set to include the raw materials for making each solvent/cleaning system, transportation of the materials from manufature to New York City, and waste disposal. Once the goal and system boundaries are set, the next step is to decide the funtional unit. The functional unit serves to even out the study by providing a quantified description of the performance requirements that the product system fulfills (ISO 14040:1997(E) section 3.5).

 The functional unit for Part A examined 1 kg of each chemical.  For Part B the functional unit examined the specified amount of cleaning system required to remove restoration paint from 10 square meters of a specific sculpture.  The amount required in Part B depended on the cleaning system and its efficiency, so it varied somewhat.

 Part A evaluated 40 solvents typically used for treatment. These solvents were evaluated cradle to gate, meaning from production to market.  The use phase was not included because the use phases of some of the chemicals under certain circumstances can be too complex for an initial, preliminary study. So, this study focused only on the environmental impact of each material, limiting its use to designing treatments only based on minimizing environmental impact.  According to this LCA, of the 40 solvents examined, acetic anhydride, fungicide, and benzyl alcohol have the highest environmental impact because of their production methods. Depending on the impact category, ammonium chloride, ethanol, benzene, and toluene have the lowest impact from cradel to gate.  However, this information is only partially helpful for conservators because we work in such close proximity to the chemicals that human health impact cannot be ignored. This is very important- it all has to do with exposure level and type of exposure



How might it affect the environment?

Normal environmental concentrations of benzene are unlikely to damage animals or plants. It does have a low to moderate toxicity for aquatic organisms, but this is only likely to be apparent when high concentrations arise from significant spills. Benzene quickly reacts with other chemicals in the air and is thus removed within a few days of release. In soils and water bodies it breaks down more slowly and can pass into groundwater where it can persist for weeks. Benzene does not accumulate in animals or plants. As a VOC, air-borne benzene can react with other air pollution to form ground levels ozone which can damage crops and materials. It is however unlikely that benzene has any environmental effects at a global level.

How might exposure to it affect human health?

Benzene is a proven carcinogen. However, exposure to normal environmental concentrations in air (from the vapourisation of petrol during re-fuelling of vehicles, from tobacco smoke, glues, paint, furniture wax and detergents) is thought unlikely to be dangerous in this respect. Inhalation of extremely high levels of benzene (following an accidental releae) could be fatal and longer term exposure to lower concentrations (in occupational settings for example) may damage blood-forming organs. When ingested or applied directly to the skin (only likely in occupational settings), benzene is very toxic. Inhalation of ground level ozone (in the formation of which benzene can be involved) can exacerbate respiratory conditions such as asthma.


 Part B evaluated six cleaning methods based on a current project in Sarah Nunberg’s studio.  The functional unit for this study looked at  the impact of each cleaning system used to remove an all covering restoration paint from 10 square meters of artwork. This study evaluated the cleaning systems from cradle to grave, meaning it included the use phase as well as the production and disposal. Impact categories included both environmental health, and human health (acidification, exotoxicity, eutrophication, global warming, ozone depetion, photochemical oxidation, carcinogenics, non-carcinogenics, and respiratory effects).

The cleaning methods examined are outlined in the chart below:





direct application of buffered water

buffered water


PVA borate gel with PH 8.5 water

physical gel


PVA borate gel with distilled water

physical gel


PVA borate gel with 99% isopropanol

physical gel


chemical gel in isopropanol

chemical gel


xanthan gum gel

solvent gel


The LCA results indicate that any system with isopropanol results in the highest human health impact, so because the Xanthan gum gel requires isopropanol to effectively remove the restoration paint, it would have as high an impact as the PVA borate gel. Most noteably, the difference in respiratory effects between the most harmful (Method 5) and the least harmful (Method 1) was 112%, demonstrating that the chemical gel (and Xanthum gum) with isopropanol poses a great threat to the environment and to human health.

The full report will be available in the FAIC LCA Library.

We would be delighted to hear from you with comments or questions, please contact us at and 

 Post 5 in this series describes LCA #3 as a comparison of energy use in microenvironments and storage rooms.

This research project is funded by the National Endowment for the Humanities, Grant PR-253401-17, from the Division of Preservation and Access. Team Members: Eric Pourchot, FAIC; Sarah Nunberg, Objects Conservation Studio; Sarah Sutton, Sustainable Museums; Matthew Eckelman, PhD., Engineer, Northeastern University; Pamela Hatchfield, Museum of Fine Arts Boston; and Michael C. Henry, P.E. & AIA, Watson & Henry Associates.