Solvent Choice

Solvent Use

According to the EPA,[1] the use of solvents contributes to our greenhouse gas emissions in the form of volatile organic compounds, usually hydrocarbons. Your fume hood simply extracts the solvent from the lab and evaporates it into the atmosphere. Chemical compounds in the solvents we use become pollutants when they enter the environment through off-gassing or disposal with potential adverse impact on our ecosystems. The definition of what a pollutant is evolves over time as we learn more about our impact on the environment.

Before undertaking conservation treatments that involve solvent use, please consider ways to alter your technique to use less solvents or less toxic solvents. The Health and Safety Committee[2] has created an excellent and thorough document on use and disposal of solvents.[3] Among the recommendations in the document is the following:

• consider use of alternative materials
• order only what you need
• use only what you need
• reuse what you can

Other handy suggestions are:

• Find the least toxic alternative. An excellent resource for solvent selection is the National Archives Solvent Solver[4]program which uses the principles of Teas Fractional Solubility Parameters to help the user design a mixture of solvents that will have the same properties as a more toxic solvent. For example, a THF substitute can be made with acetone, ethanol, and heptane. Or, an MEK substitute can be made with acetone, ethyl acetate, and mineral spirits. Note: this program is not Mac compatible.
• In your treatments, look for alternatives to petroleum based products such as water based systems, gels, and steam. (Gel systems often use a larger amount of a less toxic solvent.(Stavroudis 2010))
• Read through suggestions in specialty group sections of the AIC wiki to direct you to the most effective' least wasteful treatment procedure. For example, Chapter 15: Hinge, Tape, and Adhesive Removal in the Paper Conservation Catalog Wiki[5] gives information about the specific adhesives found in different products and suggests non-solvent techniques for reducing them.
• Find a better use of chelators and surfactants requiring less clearing and/or clearing with less toxic solvents.(Kronkright 2010)
• Keep your math figures so that you can easily mix up a small batch of a solvent mixture in the future, rather than relying on an easy measurement such as 100mL each time.
• Improve solvent storage to reduce or eliminate evaporation.
• Do not leave solvent containers open. Self-closing solvent dispensers cut down on evaporation.
• Try to pour from small containers, reducing spills and evaporation in the transfer.
• Clean brushes in used solvent rather than new solvent.

Solvent Choice

This entry is a Draft

We are researching individual solvents, and while we don't plan on creating a rating system, we will be posting information regarding

• manufacture
• environmental impact
• disposal implications
• recycling possiblities

We had hoped to present information that would guide conservators to solvent selection according to minimal pollution contribution, as there are many guides for human health and safety, but this information is not yet readily available. We looked for solvent rating systems and this chart summarizes the information we compiled.

Solvent Table

Even when we switch to more ‘natural’ substitutions (e.g. xanthan gum), it is often difficult to find, even in the MSDS, exact toxicological, ecological, or disposal information. Some artists and materials manufacturers are starting to provide this information with their works or products but it is still uncommon.(Daly-Hartin 2010)

Acetone: has negligible ground level ozone forming properties, is a good alternative to other, more toxic chemicals. It is an acceptable substitute for ozone depleting compounds

Ammonia: occurs naturally and is produced by human activity. It is a colorless gas with a distinct odor that can be dissolved in water and quickly turns back into gas when exposed to oxygen. It is used as a fertilizer in agriculture.

Green Chemistry technologies are beginning to offer options to the petroleum based products that we use. These technologies, supported by the EPA, aim to reduce waste, eliminate "end-of-the-pipe" treatments, offer safer products, reduce use of energy and resources, and supply the consumer with more competitive materials that produce less pollutants.

Chris Stavroudis. 2010. Personal communication

Dale Kronkright. 2010. Personal communication

Debra Daly-Hartin. 2010. Personal communication