Using Solvents: Rules for Handling and Disposal
Paints, solvents, or any art materials, for that matter, are not inherently dangerous. The dangers come from improper management of the materials. As artists, we often become complacent to the dangers of our studios because of deadlines, lack of safety equipment and resources, and lack of easily accessible information. However, in order to keep our families and us safe, learning about studio hazards and materials management needs to be a priority.
Of everything in the studio, solvents are some of the most potentially dangerous art materials if handled improperly. It’s important to learn what solvents are, why they are dangerous and what you can do to handle them safely.
What is a solvent?
Basically, a solvent is a liquid that is used to dissolve a solid material. There are dozens of different types of solvents, ranging from water to gasoline. Solvents can be found in thousands of household products and art supplies — markers, glues, chemicals for processing photographs, varnishes, etc. — or in pure forms, such as turpentine, mineral spirits, odorless mineral spirits. (Note: Alkyds or alcohol-based mediums are also technically solvents, though their toxicity and dangers are minimal. For more on this, read Solvent-Free and Safer Solvent Solutions for Oil Painters.)
Painters sometimes use pure solvents to thin their paint, dissolve pigments and adjust drying times. In the case of watercolor paint or gouache, which uses a corn syrup or honey as its binder, water can be used as the solvent. For acrylic paint, which has a petroleum-derived binder, there are special chemical mediums designed to act dilutants rather than solvents (merely thinning out the paint, but not dissolving the pigments). Oil painters must use stronger solvents because of the oil binder. The most common paint solvents are turpentine, mineral spirits and odorless mineral spirits. Some artists also use solvents to clean their brushes.
Why are solvents dangerous?
Keep a binder filled with the Material Safety Data Sheets (MSDS)for every art material you are using. While the MSDS may not be totally comprehensive, it can at least provide some information to your doctor or veterinarian in case of an emergency.
As solvents dry and evaporate, they release toxins into the air. If you’ve ever experienced that light-headed feeling when working with solvents, it is because the soft tissue in your brain and your nervous system are two of the first places in your body that are affected by evaporating solvents. Similar to the effects of alcohol intoxication, prolonged exposure to solvents over the course of several years causes long-term damage. The damage can become extremely serious, even leading to a type of permanent brain damage called chronic toxic encephalopathy. This can lead to memory loss and problems with dexterity. Exposure to solvents can also affect internal organs, and has been linked to cancer and birth defects.
Which solvents are safest?
Determining which solvents are the safest and how long you can endure exposure may not be as simple as reading a product label. “Natural” products are not necessarily safe. For example, while it’s fairly well known among artists that turpentine is the most toxic solvent, it is a natural substance derived from the pine tree. Less commonly understood are citrus oil and d-limonene, two ingredients often found in citrus solvents. While they may have a more pleasant smell than other solvents, both of these substances, particularly d-limonene, are some of the most toxic solvents available, and have been linked to cancer.
Outside of water, there are no totally safe solvents, though there are some that are significantly safer than others. Some manufacturers claim that certain odorless mineral spirits are safe because the aromatic hydrocarbons, which are responsible for much of the smell and toxicity of mineral spirits, have been removed. While less dangerous, odorless mineral spirits still contain small amounts of aliphatic hydrocarbons. To date, there is not enough conclusive evidence to say that solvents without aromatic hydrocarbons are completely safe, so be wary of prolonged exposure and usage, even if you can’t smell the solvent as much.
I know it’s tough, but try to avoid eating and drinking in your studio, especially if you are a painter. Many of the pigments in paints contain heavy metals, including Cadmiums, Cobalts, Chromiums and most obviously Lead White, which can damage your liver and kidneys when ingested. Some of the heavy metals, including Lead, never get expelled from your system, so be especially careful. Also, breathing in pigment particles can be just as bad if not worse in some cases, so if you mix your paint, or if you sand your boards, make sure you wear a mask and do so in an appropriately ventilated area.
You need to consider several things when working with a solvent: Threshold Limit Value, Evaporation Rate, Flash Point and Toxic Effects. You should be able to find most if not all of this information on a product’s Material Safety Data Sheets (MSDSs), which can be obtained from the manufacturer. Remember, though, that not all manufacturers update their MSDSs regularly, so research further if anything is questionable or unclear.
(Note: While there are dozens of different kinds of solvents, the comparisons below use examples of turpentine, mineral spirits and odorless mineral spirits, which are used most frequently. Be sure to consult The Artist’s Complete Health and Safety Guide for specific information on these and other solvents.)
Threshold Limit Value (TLV): This number indicates how long you can work with a solvent without experiencing adverse effects. This number is particularly useful for industrial applications or for artists working with large quantities of solvents. Consult The Artist’s Complete Health and Safety Guide for a comparison of all solvents’ TLVs. These numbers can be difficult to interpret. For practical purposes, it may be easier for an artist to simply look at the Evaporation Rate, which will give a good indication of the potential TLV.
Evaporation Rate: In order to understand the precautions necessary for handling a particular solvent, you must examine the rate of evaporation. Once a particular solvent-containing material (ex. paint mixed with solvent, or marker) is applied to a surface and dries, the solvents in that material evaporates. At that point, nothing remains of the solvent, with the exception of some turpentines and low-end mineral or odorless mineral spirits, which can sometimes leave a residue in the container (or on your surface). How fast a solvent evaporates indicates how intense your exposure to the evaporating solvents will be.
- Turpentine – Fast
- Mineral Spirits – Slow
- Odorless Mineral Spirits – Slow
- Gamsol Odorless Mineral Spirits – Very Slow
By comparing these solvents, we see that Mineral Spirits or Odorless Mineral Spirits have significantly lower rates of evaporation (*For example, you can work with Gamsol Odorless Mineral Spirits three times longer than turpentine). This means if you are working with a turpentine or turpentine-based product, you need to be very aware of how long you are exposing yourself to the turpentine, as your body can withstand far less.
Flash Point: Flash point is simply the temperature at which a substance may ignite. Solvents can create real dangers in terms of storage and disposal because flash points can be as low as 95 degrees Fahrenheit for turpentine (see storage and disposal tips below).
- Turpentine – 95 degrees
- Mineral Spirits – 105 degrees
- Odorless Mineral Spirits – 125 degrees
- *Gamsol Odorless Mineral Spirits – 145 degrees
Looking at the examples above, we see that using odorless mineral spirits or Gamsol Odorless Mineral Spirits are far less risky than turpentine or straight mineral spirits. (Note: To date, Gamsol is the safest odorless mineral spirits we’ve found regarding Evaporation Rates and Flash Points. If you know of another, please feel free to share.)
If nothing else, you certainly want your paintings to be archival, so be careful not to “water down” oil paint with too much solvent, or you will risk the integrity of the binder. Gamblin Artists Colors is a leader in teaching artists archival painting methods. Their Web site states: “In the first layer or two, you can use only solvent to thin oil colors. I recommend you use only pure odorless mineral spirits. Be careful not to thin too much or you may break the binder. If you prefer to apply paint that is as thin as water, add 25% medium to your solvent to ensure your initial layer adheres well.” For more archival oil painting from Gamblin, click here.
Toxic Effects: What kinds of effects can the solvents you are using have on you or those around you? For example, did you know that turpentine can be absorbed directly through unbroken skin, whereas mineral spirits and odorless mineral spirits cannot? Therefore, even incidental contact with turpentine in a well-ventilated area puts you at significant risk for internal damage. Consult The Artist’s Complete Health and Safety Guide for a list of toxic effects for each solvent.
Regardless of what solvent you use, proper ventilation is necessary. For plein air painters, the exposure is minimal, but the rest of us can take a lesson from them: Fresh air is good. Open a window, and place a fan on the opposite side of the room, allowing the air to circulate between the painting and the outside. This is called “dilution ventilation.” In some cases, a window may not be adequate, and an exhaust fan may be required. Click here to download the Safety Guide for Art Studios from United Educators, which includes a section on ventilation, or refer to The Artist’s Complete Health and Safety Guide.
Be sure all of your containers are properly labeled (even the jars you pour your solvents into) and covered. Contact your local government to find out what their requirements are for storage of solvents, but consider a flammable storage cabinet (click here to link to the Safety Storage Cabinet, available from Blick Art Supplies). Also, keep a fire extinguisher — one that is approved for solvent fires — handy in your studio.
Savannah College of Art and Design tries to ensure that their students are exposed to as little solvent as possible in their painting studios. They forbid the use of Pure Spirits of Gum Turpentine and Damar Varnish. In fact, the only approved solvents are: Sansodor, Gamsol and Grumtine. The SCAD painting department approves only a sparing use of the solvents, and does not permit that solvents be used for cleaning brushes. Instead, they encourage students to clean brushes with oil, wiping off excess with paper towels, disposing of paper towels in approved containers, and washing the brushes with soap and water.
Savannah College of Art and Design uses a company called Safety Kleen to dispose of their liquid solvent wastes and solvent-soaked rags. Students are required to pour all liquid solvents into one container in each classroom. Safety Kleen says that “all of the used fluid compounds are reclaimed, cleaned and reused.” For solvent-soaked rags, there is a second container. Safety Kleen recycles the rags using high-temperature incineration that converts the rags into fuel for cement kilns. “The organic compounds in the waste are burned as fuel, while the inorganic residue is incorporated into the cement product … This is an environmentally-safe and EPA approved way to recycle rags into energy.”
While some classes are completely solvent-free, like those taught by Professor Stephen Knudson (refer to his tips on Solvent-free Painting ), SCAD recommends that students using solvents for their paintings use an OSHA-approved charcoal filter mask. One filter lasts approximately 30 minutes, so you will need to buy multiple filters. SCAD also provides disposable rubber gloves to students working with solvents. As an alternative, you can also try a barrier cream as a minimal means of protection.
Contact your local department of environmental protection, water treatment facility or other appropriate government agency to find out where to dispose of your rags and liquid solvents. Also, check with them about what to do in the case of accidental spills.
NEVER toss solvent-soaked rags or paper towels in the garbage. They can ignite. Instead, store them in self-closing oily waste cans, such as those used for industrial purposes, in order to prevent potential fires. Click here to see the Justrite Oily Materials Waste Cans sold by Blick Art Supplies. The 6-gallon sells for about $70.
NEVER pour solvents down the drain. This is not only illegal in most areas of the country, but also very unsafe and hazardous to the environment. You don’t want solvents contaminating the ground water. Keep used solvents in a closed container and dispose of per your local government’s instructions. Ideally, you should use a container that is intended to house flammable liquids before they are disposed of properly, such as Justrite’s Safety Cans, also available at Blick Art Supplies. The cans cost between $35 and $50.
While there may be alternatives to using solvents, such as solvent-free painting, solvents with lower-toxicity levels or water-based products, as professional artists, you are capable of making informed decisions about what products you do and do not choose to use. The problem is that some of the information is not readily available, nor is safety a focus in many academic training environments. If you use solvents of any kind, it’s important to seek out the information you need to store, handle, apply and dispose of them in the proper and safest manner. AC
An artist and writer, Kim Hall is the former Editor of Professional Artist. She holds a B.A. in Art from the University of Central Florida and an M.A. in Arts Administration from Savannah College of Art and Design. Kim can be reached at [email protected].