Dipropylene glycol as an oil paint medium

​Hi there….one thing to keep in mind is that there is still a lot to be done in terms of testing when it comes to glycol ethers. They can span the gamut when dealing with toxicity….but also this should NOT be considered a binder. It falls under a category of solvents with varying ranges of volatility. So while we cannot speak to issues related to preservation (e.g. yellowing, etc.) here is some more information that follows up on Health and Safety concerns in the AIC News (Vol.8…thanks to MITRA’s Health and Safety point person Kerith Koss Shrager for this):

Some Chemical Things Considered: Glycol ethers and Glymes: Making sense of confusing terminology

Conservators often work very closely with solvents, so it is important to be informed about their hazards and to stay up-to-date on terminology and naming conventions, in order to recognize which solvents may require more caution. Glycol ethers are a large class of solvents. They may be found in many common household products, including latex paints, paint strippers, household cleaners and detergents, batteries, brake fluid, printing inks, plastics, adhesives, perfumes, and cosmetics. Glycol ethers have historically been used in the conservation field as solvents or diluents in coatings and varnishes, adhesives such as B-72, and solvent mixtures for cleaning. Because of concerns about their safety, the use of glycol ethers in conservation has been reduced over the past 30 years. Glycol ether solvents are used in the ninhydrin test for protein, and the AIC Paper Conservation Catalog (www.conservation-wiki.com/wiki/ Paper_Conservation_Catalog) lists a glycol ether as a possible additive in Jade 454 PVA adhesive. Glycol ethers often do not appear on product labels, and may be listed by a confusing variety of names, including chemical names, trivial names, acronyms, and proprietary names. For example, the chemical “ethylene glycol monoethyl ether” may also be known as EEGE, Cellosolve, ethyl Cellosolve, or 2-Ethoxyethanol. While conservators probably know glycol ethers can be dangerous, you might not be familiar with all of the various names by which they may be identified (see table). In particular the name “glyme” has been used recently by the EPA: “glyme” is a trivial name which properly refers only to glycol methyl ethers but is confusingly used by the EPA to also refer to other glycol ethers including diethyl and dibutyl ethers. Of the many glycol ether solvents, only a few have been studied in depth. Several glycol ethers have been found to cause adverse reproductive, developmental, and other health effects. According to the California Department of Health: “Overexposure to glycol ethers can cause anemia…intoxication similar to the effects of alcohol, and irritation of the eyes, nose, or skin. In laboratory animals, low-level exposure to certain glycol ethers can cause birth defects and can damage a male’s sperm and testicles. There is some evidence that workplace exposure can reduce human sperm counts.” Exposure routes may include inhalation of solvent vapors and absorption through the skin; some glycol ethers can penetrate gloves without changing their appearance. Recently, the EPA proposed a Significant New Use Rule (SNUR) related to a list of 14 glycol ethers, which would allow the EPA to evaluate and possibly prohibit the use of these chemicals in consumer products. The EPA has found that while potential exposure to the 14 chemicals is currently limited, there is reason to believe their use might become more common in products including printing inks, paints and coatings, and batteries. The SNUR was issued because of the potential health aic news, May 2013 9 hazards of glycol ethers: “EPA has concerns about the 14 glymes listed in this SNUR, all of which have similar chemical structures. EPA is concerned about the reproductive and/or developmental toxicity of monoglyme, diglyme, and ethylglyme and believes that individuals could suffer adverse effects from their use. In addition, EPA has concerns about the remaining 11 glymes due to the lack of available use, exposure, and toxicity information.” Glymes and glycol ethers have been of concern to conservators for quite some time, and alternatives to the use of glycol ethers in conservation have been discussed for decades, but conservators may still use these chemicals or have older supplies in chemical storage. In 2003, OSHA withdrew its proposed standards on workplace exposure to 2-ethoxyethanol and 2-methoxyethanol and their acetates because there were “few, if any, remaining opportunities for workplace exposure to these glycol ethers.” It is important to keep in mind that conservators often use chemicals in ways and situations that many other workers do not, and therefore government authorities such as OSHA and the EPA are less likely to take common conservation exposures into account when creating regulations. EPA and OSHA regulations may also be delayed by requirements for lengthy congressional hearings. Toxicological data on these chemicals still exists regardless of the status of government regulation, however, and conservators should be aware of other sources for safety information, including the more current 2012 occupational exposure limits established by the American Conference of Governmental Industrial Hygienists. The ACGIH exposure limits for 2-ethoxyethanol and 2-methoxyethanol are extremely low (5.0 ppm and 0.1 ppm, respectively, as an 8-hour time weighted average) as reflects their high toxicity. For additional resources, see the Health and Safety Committee Guide to Technical Resources for the Conservator (www.conservation-wiki.com/wiki/HS_Health_and_Safety_ Technical_Resources_for_the_Conservator). Safe working controls are definitely needed for glycol ethers, and conservators should take care to handle these chemicals with precaution.